NASA/TM--2001-210753

Thermodynamic Database for the

NdO1.5-YO1.5-YbO1.5-ScOi.5-ZrO2 System

Nathan S. Jacobson and Evan H. Copland

Glenn Research Center, Cleveland, Ohio

Larry Kaufman

Consultant, Brookline, Massachusetts

|

September 2001
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NASA / TM--2001-210753

Thermodynamic Database for the

NdO1.5-YO1.5-YbO1.5-ScO1.5-ZrO2 System

Nathan S. Jacobson and Evan H. Copland

Glenn Research Center, Cleveland, Ohio

Larry Kaufman

Consultant, Brookline, Massachusetts

National Aeronautics and

Space Administration

Glenn Research Center

September 2001
This report is a formal draft or working

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Availableelectronicali_rathttp://gltrs.grcinas-_.-g-6-_;TGLTRS _ - - : :
THERMODYNAMIC DATABASE FOR THE

NdOl.s-YO,.s-YbOl:SCO,:ZrO_ SYSTEM

Nathan S. Jacobson and Evan H. Copland

National Aeronautics and Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Larry Kaufman

Consultant

Brookline, Massachusetts 02445

SUMMARY

A database for YO, :NdO,:YbO, :ScOl.:ZrO 2for ThermoCalc* has been developed. The basis of this work is

the YO,:ZrO, assessment by Du et al. (ref. 1). Experimentally only the YO, :ZrO: system has been well-studied.

All other systems are only approximately known. The major simplification in this work is the treatment of each

single cation unit as a component. The pure liquid oxides are taken as reference states and two term lattice stability

descriptions are used for each of the components. The limited experimental phase diagrams are reproduced.

I. INTRODUCTION

The rare earth oxide stabilized zirconias are of considerable technological importance. Applications range from

thermal barrier coatings for turbine blades to electrodes for sensors and fuel cells. The most widely used system is

Y20:ZrO:. The phase diagram for this system has been extensively studied (refs. 2 to 11) Further, there are several

thermodynamic assessments and calculated phase diagrams in the literature for this and related systems (refs. 1, 12

to 19).

In this report we also consider the stabilizers: Yb_,O_, Sc_O_, and Nd_,O3. These different stabilizers alone and in

combinations may offer improved properties. However, both experimental phase diagrams and thermodynamic data

for these systems are very limited (refs. 20 to 30). Reliable phase and thermodynamic information over a range of

compositions and temperatures is essential to understand the processing and properties of zirconia with Y20_, Yb203,

Sc_O 3, and Nd,O 3stabilizers.

Figures 1 to 10 give the available psuedo-binary phase diagrams for the systems (refs. 22 to 30) listed in

table I. The most complete and most recent phase diagrams are given. In the case of Y20:ZrO_, two phase diagrams

are shown in figures 1(a) and (b). The first diagram from Stubican et al. (refs. 11 and 22) includes one intermediate

compound--Zr3Y_O_,. The second diagram (ref. 23) also includes an ordered hexagonal phase--ZrY00,2. However,

the existence of the second compound remains controversial and will not be considered here. In addition, the primary interest is in the ZrO:rich portion of the diagram and therefore its existence is not important in the present

study. Figures 2(a) and (b) are the available diagrams for the Yb,O:ZrO: system. Figure 2(a) primarily shows the

liquidus and figure 2(b) shows the solid phases. Note that these are similar to the Y20:ZrO: diagram and shows an

analogous intermediate phase--Zr3Yb4Ot:. However Zr_Yb4Ob2 is stable to 1612 °C and Zr3Y4Oi2 is stable to only to

1250 °C (fig. l(a)) or 1330 °C (fig. 1(b)). Figures 3 to 10 are the remaining available binaries. Most of these diagrams are incomplete and have many approximate boundaries ..............

The addition of two (or more) stabilizing rare earth oxides to zirconia may lead to some interesting properties.

Yet only a portion of the Y:O:Yb:O3-ZrO 2ternary diagram has been determined experimentally (ref. 31). Three

isothermal sections are shown in figures 1l(a) to (c). The major features of these systems are a continuous solid solution of tetragonal zirconia and cubic zirconia with both Y203 and Yb203. Note also that the two intermediate corn-.

pounds--ZLY40,: and ZLYb,O,2 connect at lower temperatures. At higher temperatures Zr,Y_O,: becomes unstable

and only Zr3Yb_O_2 protrudes into the ternary. At the highest temperatures, both compounds are unstable. No other

ZrO, rare earth oxide experimental temaries were found.

"The first calculations of these types of refractory oxide phase diagrams were done in 1988 by Kaufman

(ref. 14). Kaufman treats each oxide unit as a component. He sets the liquid oxide as a reference state and uses twoterm lattice stabilities to describe each end point oxide. Thus the lattice stability of a particular polymorph becomes

*ThermoCalc AB, Stockholm, Sweden.

NASA/TM--2001-210753 1
theenergytoformthatpolymorphfromtheliquid.Duetal.,(refs.1and15)havedonetwoassessments ofthe

Y_,O_-ZrO:, usingtheLukas programs (ref. 32) to derive phase descriptions that best fit all the available experimental

data. Their first assessment (ref. 1) also uses the liquid as the reference state. Their second assessment (ref. 15) invokes the standard element reference state (SER) and uses Gibbs energy expressions for each phase.

This report discusses the development of a Thermo-Calc database for the multicomponent system: Nd203-Sc203-

Yb_O_-Y,O_-ZrO:. The quantities of Duet al., for ZrO,-Y:O_ (ref. 1) are used directly and other binaries are developed based on this. Duet al., (ref. l) perform two optimizations for the ZrO2-Y:O , system--using a different set of

liquidus data for each optinfization. Their second optimization values are used here. The rare earth oxides are norrealized to one cation: NdO,.5-ScO, _-YbO_ _-YOjZrO v Each of these one cation oxide units are treated as a component. Two-term lattice stability phase descriptions referenced to the liquid state are used, which are less complex

than the Gibbs energy phase descriptions based on the standard element reference state.

The entire database in standard Thermo-Calc *.tdb format is given in appendix I. In the following report, we

discuss this database and the calculation of binar T and higher order diagrams in the NdaO_-Sc:O3-Yb,O_-Y203-ZrO 2

system.

II. LATTICE STABILITIES FOR END-POINTS

In order to estimate the lattice stabilities with respect to the liquid state, we need the enthalpies and entropies for

the polymorphic transformations. Only limited information is available, particularly on the solid/solid transformations. These data (refs. 33 to 35) are shown in table II. As noted, each oxide is normalized to one mole of cation. The

oxide abbreviations are given in table III.

It is important to discuss the compositional difference between the calculations and the measured values in

table II and figures 1 to 11. The experimental phase diagrams are for RE203-ZrO 2 (RE = Rare Earth Element) and

will be referred to as such; the calculated diagrams are for REO_.5-ZrO ., and will be referred to as such. In order to

compare the two, we need to convert from mole fraction x(RE:O3), in RE203-ZrO: to mole fraction x(REO, s), in

REO_.5-ZrO.,. Note that

x(RE203 in RE20 3 - ZrO2) = n(RE20 3 in RE203 - ZrO2)

n(RE20 3 in RE20 3 -ZrO2)+n(ZrO 2 in RE20 3 -ZrO2)

(1)

Here n is the number of moles. The composition for REO, cZrO_ is:

x(REOL. 5 in REOI. 5 - ZrO2) = n(REOI.5 in REO 1.5- ZrO2) (2)

n(REOL5 in REOI. 5 - ZrO2) + n(ZrO 2 in REOI. 5 - Zr02)

Note that for each composition n(ZrO) the same and that n (RE20 0 = _/_n (REO, 0. So now:

x(REOI.5) = 2 x(RE203) (3)

2 x(RE 203) + (1 - x(RE20 3))

Table IV shows the equivalent compositions.

Now consider the derivation of the lattice stabilities for each oxide. The most information is available for ZrO,,

which undergoes three transformations (ref. 36):

ZrO.,: Monoclinic _ Tetragonal _ Cubic _ Liquid (4)

The approach of Kaufman (ref. 14) and ThermoCalc notation are used in the following discussion.

The liquid phase is taken as the reference state and thus:

G(L, ZM; 0) = 0.0 (5)

NASA/TM_2001-210753 2
Forthecubicphase:

G(C,ZM;0)= AH c'.- T AScL = -87027 + 29.471T (6)

This is the value from Kubachewski and Alcock (ref. 33) with a melting point of 2953 K. More recent

investigations have given the melting point of cubic zirconia as 2983 K. Du and Jin (ref. 1) adjust equation (6) to

reflect this:

G(C, ZM; 0) = -87986.6 + 29.496T (7)

The tetragonal to cubic transformation temperature is given as 2568 K (33) and thus:

AH T-c - T ASr c = -5941 + 2.313T (8)

Again Du and Jin (ref. 1) adjust this for a more recent transformation temperature of 2642 K:

AH r-c - T ASrc = -5941 + 2.249T (9)

In order to obtain the free energy of the tetragonal phase referenced to the liquid, equations (7) and (9) are

added:

G(T, ZM; 0) = AH T-t- T ASVL= -93927 + 31.745T (10)

From equation (10) a 'melting point' for the tetragonal phase can be calculated to be 2959 K. A metastable

melting point must always be less than the melting point of the stable phase.

Table II indicates some disagreement on the monoclinic to tetragonal transformation temperature and heat. Here

we take the temperature as 1454 K and the heat as 6000 joules/mol:

AH M-T- T ASMv= --6000 + 4.127T (11)

The free energy of the monoclinic phase referenced to the liquid is obtained by adding equations (10) and (11):

G(M, ZM; 0) = AH M-t- T AS M-t= -99927 + 35.872T (12)

For the other oxides--YO_ 5, YbO_ 5, NdO_ 5, ScO, 5-a similar approach was followed. However, less data is

available. Of these the most data is available for YO,. 5.YO_ 5undergoes two phase transformations:

YO,.5: Cubic _ Hexagonal _ Liquid (13)

Again, the liquid phase is taken as the reference state:

G(L, YM; 0) = 0.0 (14)

The melting point of the hexagonal phase is accepted as 2712 K. Kaufman (ref. 14) estimates the lattice stability

of the hexagonal phase as:

G(H,YM; 0) = AH "-L- T AS"L = -56735 + 20.92T (15)

This enthaply is somewhat more than half the IVTAN (ref. 34) data for melting of Y_O 3, but more in line with

Kubachewski's (ref. 34) values for alumina heat of melting (54 kJ/mol A10,5).

The only measured transition heat for the polymorphs of a rare earth oxide was that for Y203 cubic to hexagonal, as reported in IVTAN to be 54 kJ/mol. However, this number seems much too high for a solid/sofid transition

such as this. Kaufman (ref. 14) estimates the heat to be about 10 kJ/mol and it seems more reasonable to use this

value. Accepting the cubic to hexagonal transformation temperature of 2550 K the lattice stability for the cubic

phase becomes:

G(C,YM; 0) = AH c-t-- T AS c-L= -67419 + 25.105T (16)

NASA/TM--2001-210753 3
ThebehaviorofYbO_siscontroversial. ThetwopublishedphasediagramswithYbOl_donotagree.The

YbOl_-ZrO_diagram(fig.2)indicatesthatthehexagonal phasemelts;whereastheYbO,5-NdOj. _diagram(fig.9)

indicatesthatthecubicphasemelts.Itisassumedthathehexagonal phaseofYbO,._melts,inanalog3, withYO_.

Thereforethephasesequencewithtemperatureistakenas:

YbO_._: Cubic--->Hexagonal _ Liquid

ForNdO,._, thephasesequencewithtemperatureappearstobe:

NdO,._: Nphase--_Hexagonal -_ Cubic--_Liquid

LittleinformationisavailableforScO]_andit isassumedthatthe cubic phase melts. From the melting points

and estimated heats of fusion, the lattice stabilities are derived as shown in the database (appendix I)

III. INTERACTION PARAMETERS: CUBIC, MONOCLINIC, TETRAGONAL, N PHASE, NM PHASE

In the binary case, each of the above solution phases are described by the following expression for the free

energy:

2 2

Gm(x,T) = Exi °G i (T)+ RTEx i ln xi + exG m (17)

i=l i=l

The first term is the sum of the lattice stabilities for each of two components. These are discussed in the previous section. The Calphad approach requires a lattice stability for every component in each phase---even if a particular component does not form the phase described. For example, a lattice stability if necessary for hexagonal ZrO2,

monoctinic YO,..,, and tetragonal YO,. s. The lattice stabilities are chosen so that these phases are always unstable

(Appendix I).

The second term in equation (17) is the random mixing term for an ideal solution. The third term is the excess

Gibbs energy and accounts for the deviations from ideality. Many solution models have been developed for this term

(refs. 37 to 39). In the Calphad approach, the excess Gibbs energy is expanded as a Redlich-Kister polynomial

(ref. 37):

n

eXGm = xIx2EJL(xl -x2)J (18)

j=0

Here only the first two terms are considered:

ex o ] o 1

G_ = xlx 2 L + xlx 2 L(x I - x 2) = x,x 2 L + XlX 2 L(I - 2x2) (19)

where °L and 'L are the zero and first order interaction parameters, respectively. In assigning mole fraction designations, ThermoCalc takes the components in alphabetical order. Thus in this case x., = Xz,% and the sign of the second

term in equation (19) is always the opposite of the sign of IL for x 2> 0.5.

The shape of the Gibbs energy curves versus composition and temperature determine the stable phase fields in a

classical temperature-composition phase diagram. The first two terms in equation (17) are fixed and lead to an ideal

solution, as discussed in many textbooks (refs. 38 to 39). The variables in the excess term (°L and _L) are adjusted to

fit experimental observations for a real solution, which generally show deviations from ideality.

The YO_ 5-ZrO , system description can be simplified by introducing a miscibility gap in the cubic phase field.

This will be discussed in the next section. It follows that the_L and 'L parameters need to be adjusted to create this

feature. This is illustrated in figure 12. A single zero order term (regular solution) can only yield a symmetric miscibility gap. The 'L term is also needed to produce an asymmetric miscibility gap. The effect of the sign of _L on the

location of the miscibility gap is shown in figure 12 and table V. For the cubic phase in a REOI _-ZrO 2phase diagram, we want the miscibility gap on the ZrO2-rich side. This requires a positive 'L and a negative second term in

equation (19), which gives a second minima on the right, but less than the first minima on the left, as shown in

figure 12.

NASA/TM--2001- 210753 4
Theinteractionparameters forthefivesolidsolutionsinthissystemarethusdeterminedby(a)Usingthe

assessment ofDu(1)asaguideand(b)Estimatingnumberswhichgiveae_G,, whichwill leadtophaseregionssimilartothoseobservedintheexperimental phasediagram.

III.A.CubicSolidSolution(CubicZrO.,ssandCubicREOL_ss)

A majorfeatureoftheZrO:RareEarthOxidephasediagramsithelargecubicphasefield.Thisisevidentin

eachoftheexperimental phasediagrams(figs.1to4).

AspointedoutbyDegtyarevandVoronin(refs.12and13),mostoftheY,O:ZrO2phasediagramiscomposed

ofcubicsolidsolutionsofYOL_andZrO,.Cubiczirconiahasaclassical face-centered cubiclatticeCaF2structure.

ThecubicphaseforY.,O3hasabody-centered cubiclatticelikeMn2Q.DegtyarevandVoronin(refs.12and13)

furtherpointoutthatthisMn203structurecanbederivedfromtheCaF2structurebyremovingonequarterofthe

oxygenanions.ThusthetwocubicphasescanbederivedfromoneG-xcurvewithamiscibilitygap.

Theaboveassumptionsimplifiesthephasediagramcalculationprocedure. Themiscibilitygapoptionin

Thermo-Calcisusedwhichhastheprogramsearchforasecondfreeenergyminimum.Further,theexperimental

phasediagramsindicatethathemiscibilitygapisshiftedtotheright.

Theinteractionparameters fortheYO,:ZrO, are taken from the assessment of Duet al. (ref. 1):

L(C,YM,ZM; 0) = -12060 + l 1.156T (20)

L(C,YM,ZM; 1) = +13784 + 5.379T (21)

The first order interaction parameter is always positive and thus shifts the miscibility gap to the right (table V)

as observed experimentally.

As shown in the database (appendix I), similar interaction parameters were taken for the YbO_:ZrO_ and ScOl:

ZrO., systems. For the NdOt :ZrO .,system, the following interaction parameters are estimated:

L(C, NM, ZM; 0) = -52400 + 27T (22)

L(C, NM, ZM; 1) = +24400 +I.5T (23)

Again the first order interaction parameter is always positive and hence the miscibility gap is shifted to the right, as

the experimental phase diagram shows. Note that equation (23) yields the similar values to equation (21) at high

temperatures.

Consider the remaining interaction parameters between the various rare earth oxides. Now there is no miscibility gap and in most instances a continuous or nearly continuous cubic solution (figs. 5 to 10). Only the Yb20:Nd203

and Y_.O:Nd,O 3systems have been established with any certainty. These interaction parameters are estimated as:

L(C, BM, NM; 0) = +21425 + 2.5T (24)

L(C, BM, NM; 1) = -19600 + 8T (25)

L(C, NM, YM; 0) = +21425 + 2.5T (26)

L(C, NM, YM; 1) = -19600 + 8T (27)

The other rare earth oxide phase diagrams (Sc203-Y203, Sc203-Nd203,, Yb203-Sc203, Yb203-Y:O3) are only very

approximately known (figs. 5, 6, 8, and 10, respectively). In this case only the zero order interaction parameter is

estimated to be +20,000 J/mol.

III.B. Hexagonal Solid Solution (Hex REO, 5 ss)

As shown in figures 1(a) and (b), the hexagonal solid solution only occupies a small region of the Y20:ZrO,

phase diagram. The assessment of Duet al., gives a single Redlich-Kister term:

NASA/TM--2001-210753 5
L(H,YM,ZM;0)=50420 (28)

Asshowninfigure12,alargepositivevalueof°Lgivesasymmetricfreeenergyofmixingwithtwosmallminimaoneitherside.TheminimaontheYOj.5sidegivesthesmallhexagonal regioninthephasediagram.

Mostoftheotherhexagonal °Lsolutiontermswereestimatedto20000or35000J/tool.HoweverthephasediagramsfortheNd_,O;Y.,O_ andNd,O;Yb.,O, havebeenreported(figs.7and9,respectively). Inordertoobtainthe

hexagonal solidsolutionsacrossthesephasediagrams, thefollowingexpressions areused:

L(H,BM,NM;0)= 12750+I.5T (29)

L(H,BM,NM;1)= -1000- T (30)

L(H,YM,NM;0)= !1265+I.5T (31)

L(H,YM,NM;1)= 1000- T (32)

Boththesesetsof valuesfortheinteractionparameters giveafreeenergywithasingle,broadminimaatthe

temperatures ofinterest.

III.C.LiquidSolution

Theliquidsolutionparameters fortheYOls-ZrO:systemhavebeendeterminedbyDuetal.,(ref.1)tobe:

L(LIQ,YM,ZM;0)=-183751+ 72.4T (33)

L(LIQ,YM,ZM;1)=48733- 9.476T (34)

DuetosimilaritybetweentheliquidregionsintheYO,;ZrO2andYbOI.5-ZrO2systems, thesesameparameters

aretaken:

L(LIQ,BM,ZM;0)= -183750+ 72.4T

L(LIQ,BM,ZM;1)=48700- 9.48T

FortheNdO,;ZrO., system, a single term expression is used:

L(LIQ, NM, ZM; 0) = -20000

L(LIQ, NM, ZM; 1) = -15000

(35)

(36)

(37)

(38)

All of the ScO, 5 parameters were estimated to 20000 Jlmol. As shown in figures 3, 6, 8, and 10, virtually nothing is known about the liquid phase in the scandia systems. Thus, it is reasonable to use the above approximations.

For the other systems, zero order parameters are estimated as:

L(LIQ, BM, NM; 0) = -200

L(LIQ, BM, YM; 0) = -10000

L(LIQ, NM, YM; 0) = -200

(39)

(40)

(41)

III.D. Monoclinic Phase Solid Solution (Mon ZrO 2ss)

The monoclinic phases show very" limited solubility for a second oxide, except for the NdO,;YbO,, and

NdO, _-YO, _ systems. Again, beginning with the data from the assessment of Duet al., (ref. 1):

L(M, YM, ZM; 0) = -58223 + 98.126T (42)

NASA/TM--2001-210753 6
Theotherinteractionparameters areestimated. Onlytwotermsare used for the NdO_.._-YbO,. 5and

NdO_ 5-YOI.; systems:

L(M, BM, NM; 0) = -5000 (43)

L(M, BM, NM; 1) = 100 (44)

L(M, NM, YM; 0) = -50000 (45)

L(M, NM, YM; 1) = 1000 (46)

The remaining zero order interaction parameters are all estimated to be 20000 Jlmol.

IIII.E. Phase MN Solid Solution (MN ss)

Again, since only the YbOL.cNdOt. _and YO_.5-NdO_ 5 phase diagrams are known with any certainty, these interaction parameters are taken as:

L(MN, BM, NM; 0) = -160000 + 48T

L(MN, BM, NM; I) = 120000 - 15T

L(MN, NM, YM; 0) = -160000 + 50T

L(MN, NM, YM: 1) = 120000 + 15T

All other interaction parameters are taken as 20000 J/mol.

(47)

(48)

(49)

(50)

III.F. N Phase Solid Solution (N ss)

As above, since only the YbO_.5-NdO,. 5and YO,.5-NdO,. 5phase diagrams are known with any certainty, these

interaction parameters are taken as:

L(N, BM, NM; 0) = -15200 - 7T

L(N, BM, NM; 1) = -13000 - 6.7T

L(N, NM, YM; 0) = -15000 - 7T

L(N, NM, YM; 1) = 13000 + 5T

All other interaction parameters are taken as 20000 J/mol, except for:

L(N, NM, ZM; 0) = 50000

(51)

(52)

(53)

(54)

(55)

III.G. Tetragonal Phase Solid Solution (Tet ZrO 2ss)

This phase shows a triangular appearance in the Y203-ZrO2 phase diagram (figs. 1(a) and (b)). There is a suggestion on the other RE20_-ZrO 2phase diagrams (figs. 2 to 4) of similar behavior. The assessment of Duet al., (1)

gives:

L(T, YM, ZM; 0) = -25800 (56)

NAS A/TM--2001-210753 7
ThesamevalueisadoptedforYbOts-ZrO,5:

L(T,BM,ZM;0)=-25800

All otherinteractionparameters areestimatedtobe20000J/mol.

(57)

IV.INTERMEDIATECOMPOUNDS

In the binary NdO_ 5-ZrO_,, ScO,.;ZrO v and YbO_;ZrO, systems there are several intermediate compounds. The

Zr_Y_O_. phase has been reported by several investigators. These line compounds are treated with two sublattice

model--the ZrO 2component is on one sublattice and the YO_component is one the other sublattice. Following

Duet al.:

3 0GC-ZrO 2 + 4 0GC'_ZrO2 _ 3284.3- 2.26749T = -79536+ 24.72T

G(I/7)Zr3Y4OI2 = "_ 7

As mentioned, there is an anaIogous Zr_Yb_O,, phase. This is treated as:

(58)

G(l/7)Zr3Yb4Ol2 = -79350 + 25T (59)

To account for interchange of Y and Yb in this compound, the following solution parameter is introduced:

L(DELTA,BM,YM:ZM;0) = 10200 (6O)

The free energy of each of the compounds are chosen so that they protrude into the cubic phase. For

NdO, ;ZrO,., there exists a binary with the 1:1 composition

G(P, NM: ZM; 0) = -180450 + 57T (61)

For the ScO, 5-ZrO 2,there are several intermediate compounds, each with a range of solution according to the

experimental diagram in figure 3. However for the purpose of this approximation, we shall treat them as line compounds.

For 4(SCO, 5) •3(ZRO2), Phase RB:

G(RB, SM: ZM; 0) = -557200 + 171.5T (62)

For 2(ScO_5) .5(ZrO2) , Phase RH:

G(RH, SM: ZM; 0) = -620000 + 185T (63)

For 2(SCO, 5) ' 7(ZrO2), Phase RM:

G(RM, SM: ZM; 0) = -822800 + 258T (64)

V. RESULTS: BINARY PHASE DIAGRAMS

Having described the database, we now turn to the results for the binaries and compare them to the limited

experimental data. Figures 13 to 22 give the calculated binaries. Recall again that the experimental diagrams are for

REzO;ZrO2 whereas the calculated diagrams are for REO_._- ZrO_,.

The calculated diagrams show the same general features as the experimental diagrams. The calculated

YO_.;ZrO, phase diagram (fig. 13) is, of course, the same as that obtained by Duet al., (ref. 1) and is in good

agreement with the experimental diagram of Stublcan et al., (fig. l(a)).

All other REO, 5-ZrO .,diagrams show similar behavior to the YO, 5-ZrO .,phase diagram on the ZrOzrich side,

where most of the interest is_ The NdO, ;ZrO 2, ScO_-ZrO,, and YbO_-ZrO2diagrams are not so definitive, as much

NASA/TM--2001 -210753 8
lessexperimental dataisavailable. Nonetheless, thegeneral featuresof the experimental diagrams are reproduced on

the calculated diagrams.

The Yb20_-ZrO 2diagram is also only approximately known (fig. 2) and consists of a large cubic phase field and

one intermediate compound. This is reproduced in the calculated diagram (fig. 14).

The Nd_,O_-ZrO: experimental diagram shows a eutectic at -2115 °C and the NdO, 5-ZrO 2calculated diagram

shows the same eutectic at 2100 °C. The Nd20_-ZrO ., experimental diagram shows a euctectoid at 1440 °C, whereas

the calculated NdO, _-ZrO 2phase diagram shows this eutectoid at -1660 °C. But this part of the diagram is not wellknown.

Only a limited portion of the Sc20_-ZrO _,phase diagram is known (fig. 3). For the purpose of this approximation, the intermediate compounds (Sc2Zr70,7, Sc_,Zr50,3, Sc4Zr30,:) are treated as line compounds rather than solid

solutions. Even with this approximation, the general appearance is reproduced.

For the binaries among the rare earth oxides (Nd,O_, Sm_,O_, Yb203, Y_,O3),only the Nd.,O3-Y.,O _(fig. 7) and

Nd,O_-Yb.,O 3 (fig. 9) systems are known to any extent. The major features of these diagrams are reproduced in the

calculated diagrams (figs. 19 and 21, respectively). Both show a substantial monoclinic solid solution. The remaining rare earth oxide binaries show large cubic solid solution regions.

There are some limited activity measurements for the Y_,O3-ZrO _,system at 2773 K (ref. 40) and the Sc.,O3-ZrO .,

system at 2600 K (ref. 41) obtained via mass spectrometry. In order to compare these data to calculations from the

database described here, the mole fraction must be converted according to table IV and the activity also must be

converted to appropriate units. Belov et al. (refs. 40 and 41) show that the rare earth oxides vaporize as:

RE203(s) = 2 REO(g) + O(g) (65)

Thus the activity of RE,O 3 [a(RE203)] is defined as:

[P(REO)]2 [P(O)]

a(RE203) = [pO(REO)]2[pO(o)]

(66)

Here the quantities in the numerator are the partial pressures over the oxide in solution and the quantities in the

denominator are the partial pressures over the pure oxide--solid Y203 (presumably hexagonal) and cubic Sc203.

Next consider REOLs, which should vaporize as:

REO_.s(s) = REO(g) + V20(g) (67)

[P(REO)][P(O)] 1/2 = 4a(RE203)

a(REO1.5) [pO(REO)][pO(o)]l/2

(68)

Thus the experimental measurements need only be converted with a square root for comparison to the calculated values.

Figures 23(a and b) and 24(a and b) show the comparison of these measured activities (refs. 40 and 41) to the

calculated values from this database. For both systems the data indicate measurements were taken in a single phase

region across the diagram; whereas the phase diagrams--both experiment and calculated indicate some two phase

regions. There appears to be a conflict in the phase boundary locations. Agreement with a(ZrO_) is good, as these

data were used in the Duet al. (ref. 1) assessment. However, agreement with a(REOL. _) is only fair--these data were

not used in the assessment.

VI. RESULTS: TERNARY SECTIONS

This database can be used to approximate ternary sections. One would expect the following features in a ternary

diagram:

1. The cubic phase occupies a large region in each binary. Therefore it seems reasonable that the cubic phase

would stretch across the ternary as well.

2. The intermediate compounds should protrude into the ternary.

NASA/TM--2001-210753 9
Calculationsoftheisothermal cutsledto some convergence problems in ThermoCalc and additional steps were

necessary to force convergence. These are illustrated in the macro in appendix II. This macro also allows the variation of the ternary interaction parameter.

Figures 25(a) and (b) are isothermal cuts for the YO_ ;YbO_.;ZrO z system at 1600 K, illustrating the effects of

two different ternary interaction parameters:

Figure 24(a): L(C, BM, YM, ZM; 0) = +10000, insufficient for a continuous two phase region.

Figure 24(b): L(C, BM, YM, ZM; 0) = +100000, continuous two phase region.

In order to address issue (2) above, an interaction parameter was added for the intermediate phase. Figure 25

shows the effect of

L(C, BM, YM: ZM) = 70000

L(DELTA, BM, YM: ZM) = 10200

Figures 26(a) to (c) are the calculated ternary for 1473, 1673, and 2000 K. These can be compared to experimental sections in figure 11. The protrusion behavior as a function of temperature for the delta phase is reproduced

by these calculations. Further work is necessary to reproduce the phase boundaries of the solution phases correctly.

VI. RESULTS: HIGHER ORDER SYSTEMS

There are no reported data on higher order phase diagrams. However they can be approximated with this database. Phase data for systems with more than three components can be presented with a phase fraction diagram or an

isoplethal section with one component varying over a small range. An example of a phase fraction diagram for

ScO,;YO_-YbO_5-ZrO2is shown in figure 27. Figure 28 shows an isoplethal section for ScO,.;YO,.;YbO,;ZrO.,

with a small variation in YO_.

V/I. SUMMARY AND CONCLUSIONS

An approximate database for ScO, ;NdO_ 5-YbO_ ;YO,.5-ZrO, has been discussed. It is based on the assessment

of Du et al., for the YO,.5-ZrO .,system (ref. 1) and uses a two-term lattice stabifity description of the phases with the

liquid as the reference state. Binary phase diagrams for the other systems agree reasonably well with the limited

experimental data. Ternary and higher order diagrams require the introduction of a ternary interaction parameter and

an interaction parameter for the intermediate compounds to allow protrusion of the intermediate compounds into the

multi-component composition space. The binary systems beyond Y:O;ZrO., require additional experimental and

modeling efforts. This will provide a stronger basis for further development of the multicomponent diagrams.

NASA/TM--2001-210753 10
APPENDIX I

$ Database file written 99-12-23

$

ELEMENT /- ELECTRON GAS

ELEMENT VA VACUI/M

ELEMENT BM LIQ

ELEMENT NM LIQ

ELEMENT SM LIQ

ELEMENT YM LIQ

ELEMENT ZM LIQ

0 0000E+00 0 0000E+00 0.0000E+00!

0000E+00 0

9704E+02 0

6827E+02 0

8960E+01 0

1291E+02 0

2322E+02 0

0000E+00 0.0000E+00!

0000E+00 0,0000E+00!

0000E+00 0.0000E+00!

0000E+00 0.0000E+00!

0000E+00 0.0000E+00!

0000E+00 0.0000E+00!

FUNCTION UN ASS 2.98140E+02 0.0 ; 3.00000E+02 N !

TYPE DEFINITION % SEQ *!

DEFINE SYSTEM DEFAULT SPECIE 2 !

DEFAULT COMMAND DEF SYS ELEMENT VA ]

PHASE C % 1 1.0 !

CONSTITUENT C :BM,NM,SM,YM, ZM : !

PARAMETER G(C

PARAMETER G(C

PARAMETER G(C

PARAMETER G(C

PARAMETER G (C

PARAMETER G (C

PARAMETER G (C

PARAMETER G(C

PARAMETER G(C

REF:0 !

PARAMETER G(C BM;0) 5.00000E+02 -65942+25.105"T; 6.00000E+03 N REF:0 1

NM;0) 5.00000E+02 -65348+25.105"T; 6.00000E+03 N REF:0 !

SM;0) 5.00000E+02 -67856+25.105"T; 6.00000E+03 N REF:0 !

YM;0) 5.00000E+02 -67419+25.105"T; 6.00000E+03 N REF:0 !

ZM;0) 5.00000E+02 -87987+29.496"T; 6.00000E+03 N REF:0 !

BM,NM;0) 5.00000E+02 +21425-2.5"T; 6.00000E+03 N REF:0 !

BM,NM;I) 5.00000E+02 -19600+8"T; 6.00000E+03 N REF:0 !

BM,SM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

BM,YM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

BM,ZM;0) 5.00000E+02 -12060+II.16"T; 6.00000E+03 N

PARAMETER G(C BM,YM,ZM) 300

PARAMETER G(C

PARAMETER G (C

PARAMETER G (C

PARAMETER G (C

PARAMETER G (C

PARAMETER G (C

PARAMETER G (C

PARAMETER G (C

PARAMETER G (C

PARAMETER G (C

REF: 0 !

PARAMETER G (C, YM, ZM ; 1 )

REF: 0 !

+70000; 6000 N REF: 0 l

BM, ZM;I) 5.00000E+02 +13800+5.38"T; 6.00000E+03 N REF:0 !

NM,SM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

NM,YM;0) 5.00000E+02 +21425-2.5"T; 6.00000E+03 N REF:0 !

NM,YM;I) 5.00000E+02 +19600-8"T; 6.00000E+03 N REF:0 !

NM,ZM;0) 5.00000E+02 -52400+27"T; 6.00000E+03 N REF:0 !

NM,ZM;I) 5.00000E+02 +24400+1.5"T; 6.00000E+03 N REF:0 !

SM,YM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

SM,ZM;0) 5.00000E+02 -12000+II*T; 6.00000E+03 N REF:0 !

SM,ZM;I) 5.00000E+02 +14500+6"T; 6.00000E+03 N REF:0 !

YM,ZM;0) 5.00000E+02 -12060+II.156"T; 6.00000E+03 N

5.00000E+02 +13784+5.379"T; 6.00000E+03 N

PHASE DELTA % 2 .571 .429 !

CONSTITUENT DELTA :BM,YM : ZM :

PARAMETER G(DELTA,YM:ZM;0) 5.00000E+02 -79536+24.72"T; 6.00000E+03 N

REF;0

PARAMETER G(DELTA,BM:ZM;0) 300 -79350+25"T; 6000 N REF:0 !

PARAMETER G(DELTA,BM,YM:ZM;0) 300 +10200; 6000 N REF: 0 !

NASAfFM--2001-210753 11
PHASE H % 1 1.0

CONSTITUENT H :BM,NM,SM,YM, ZM : !

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

G(H,BM;0)

G(H,NM;0)

G(H, SM;0)

G(H,YM;0)

G(H,ZM;0)

G(H,BM,NM;0)

G(H,BM NM;I)

G (H,BM SM;0)

G (H,BM YM;0)

G (H,BM ZM;0)

G(H,NM SM;0)

G(H,NM YM;0)

G(H,NM YM;I)

G(H,NM,ZM;0)

G(H,SM,YM;0)

G(H,SM, ZM;0)

G(H,YM, ZM;0)

2.98150E+02 -55919+20.92"T; 6.00000E+03 N REF:0 !

2.98150E+02 -75697+29.29"T; 6.00000E+03 N REF:0 !

2.98150E+02 -54000+30"T; 6.00000E+03 N REF:0 !

5.00000E+02 -56735+20.92"T; 6.00000E+03 N REF:0 !

5.00000E+02 -53973+25.104"T; 6.00000E+03 N REF:0 !

5.00000E+02 +12750+1.5"T; 6.00000E+03 N REF:0 !

5.00000E+02 -1000-T; 6.00000E+03 N REF:0 !

5.00000E+02 20000; 6.00000E+03 N REF:0 !

5.00000E+02 +20000; 6.00000E+03 N REF:0 !

5.00000E+02 20000; 6.00000E+03 N REF:0 !

5.00000E+02 20000; 6.00000E+03 N REF:0 !

5.00000E+02 +I1265+1.5"T; 6.00000E+03 N REF:0 !

5.00000E+02 +!000+T; 6.00000E+03 N REF:0 !

5.00000E+02 35000; 6.00000E+03 N REF:0 !

5.00000E+02 20000; 6.00000E+03 N REF:0 !

5.00000E+02 20000; 6.00000E+03 N REF:0 !

5.00000E+02 50420; 6.00000E+03 N REF:0 !

PHASE LIQ % 1 1.0 !

CONSTITUENT LIQ :BM,NM,SM,YM,ZM : !

PAPA G(LIQ,BM;0) 298.15

PARA G(LIQ,NM;0) 298.15

PAPA G(LIQ,SM;0) 298.15

PAPA G(LIQ,YM;0) 298.15

PARA G(LIQ,ZM;0) 298.15

PARAMETER G (LIQ, BM,NM; 0) 5

PARAMETER G (LIQ, BM, SM ;0 )

PARAMETER G (LIQ, BM, YM; 0)

PARAMETER G (LIQ, BM, ZM; 0

REF :0 !

PARAMETER G (LIQ, BM, ZM; 1

REF: 0 !

PARAMETER G (LIQ, NM, SM; 0

PARAMETER G (LIQ, NM, YM; 0

PARAMETER G (LIQ, NM, ZM; 0

PARAMETER G (LIQ, NM, ZM; 1

PARAMETER G (LIQ, SM,YM; 0

PARAMETER G (LIQ, SM, ZM; 0

PARAMETER G (LIQ, YM, ZM ;0

REF :0 !

PARAMETER G (LIQ, YM, ZM ;1 )

REF: 0 !

0; 6000 N!

0; 6000 N!

0; 6000 N!

0; 6000 N!

0; 6000 N!

.00000E+02

.00000E+02

.00000E+02

.00000E+02

5.00000E+02

-200; 6.00000E+03 N REF:0 !

20000; 6.00000E+03 N REF:0 !

-i0000; 6.00000E+03 N REF:0 !

-183750+72.4"T; 6.00000E+03 N

+48700-9.48"T; 6.00000E+03 N

5.00000E+02 20000; 6.00000E+03 N REF:0

5.00000E+02 -200; 6.00000E+03 N REF:0

5.00000E+02 -20000; 6.00000E+03 N REF:0

500 -15000; 6000 N REF: 0 !

5.00000E+02 20000; 6.00000E+03 N REF:0

5.00000E+02 20000; 6.00000E+03 N REF:0

5.00000E+02 -183751+72.4"T; 6.00000E+03

5.00000E+02

!

!

!

!

N

+48733-9.476"T; 6.00000E+03 N

PHASE M % 1 1.0

CONSTITUENT M :BM,NM,SM,YM,ZM :

PARAMETER G (M,BM; 0)

PARAMETER G (M, NM ;0 )

PARAMETER G (M, SM; 0)

PARAMETER G (M, YM; 0)

PARAMETER G (M, ZM; 0)

5.00000E+02

5.00000E+02

5.00000E+02

5.00000E+02

5.00000E+02

-14000+29.915"T;

-14000+29.915"T;

-14000+29.915"T;

-14698+29.915"T;

-99979+35.9"T;

6.00000E+03 N REF:0 !

6.00000E+03 N REF:0 !

6.00000E+03 N REF:0 !

6.00000E+03 N REF:0 !

6.00000E+03 N REF:0 !

NASA/TM--2001-210753 12
PARAMETER G (M, BM,

PARAMETER G (M, BM,

PARAMETER G (M, BM

PARAMETER G (M,BM

PARAMETER G (M, BM

PARAMETER G (M,NM

PARAMETER G (M,NM

PARAMETER G (M, NM

PARAMETER G (M,NM

PARAMETER G (M, SM

PARAMETER G (M, SM

PARAMETER G (M, YM

REF: 0 !

NM;0)

NM;I)

SM; 0)

YM;0)

ZM;0)

SM;0)

YM;0)

YM;I)

ZM;0)

YM;0)

ZM;0)

ZM;0)

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

-5000; 6.00000E+03 N REF:0 !

I00; 6.00000E+03 N REF:0 !

20000; 6.00000E+03 N REF:0

20000; 6.00000E+03 N REF:0

20000; 6.00000E+03 N REF:0

20000; 6.00000E+03 N REF:0

-50000; 6.00000E+03 N REF:0

1000; 6.00000E+03 N REF:0 !

20000; 6.00000E+03 N REF:0

20000; 6.00000E+03 N REF:0

20000; 6.00000E+03 N REF:0

-58223+98.126"T; 6.00000E+03 N

PHASE MN % 1 1.0 !

CONSTITUENT MN :BM,NM,SM,YM,ZM :

PARAMETER G(MN,BM;0)

PARAMETER G(MN,NM;0)

PARAMETER G(MN,SM;0)

PARAMETER G(MN,YM;0)

PARAMETER G (MN, ZM; 0)

PARAMETER G (MN, BM, NM ; 0 )

PARAMETER G (MN, BM, NM ; 1 )

PARAMETER G(MN,BM,SM;0)

PARAMETER G(MN,BM,YM;0)

PARAMETER G(MN,BM,ZM;0)

PARAMETER G(MN,NM,SM;0)

PARAMETER G(MN,NM,YM;0)

PARAMETER G(MN,NM,YM;I)

PARAMETER G(MN,NM,ZM;0)

PARAMETER G(MN,SM,YM;0)

PARAMETER G(MN,SM,ZM;0)

PARAMETER G(MN,YM,ZM;0)

5.00000E+02

5.00000E+02

5.00000E+02

5.00000E+02

5.00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

-45000+30"T; 6.00000E+03 N REF:0 !

-60000+30"T; 6.00000E+03 N REF:0 !

-60000+30"T; 6.00000E+03 N REF:0

-45000+30"T; 6.00000E+03 N REF:0

-45000+30"T; 6.00000E+03 N REF:0 !

-160000+48"T; 6.00000E+03 N REF:0

+120000-15"T; 6.00000E+03 N REF:0

20000; 6.00000E+03 N REF:0 !

20000; 6.00000E+03 N REF:0 !

20000; 6.00000E+03 N REF:0 !

20000; 6.00000E+03 N REF:0 !

-160000+50"T; 6.00000E+03 N REF:0

-120000+15"T; 6.00000E+03 N REF:0

20000; 6.00000E+03 N REF:0 !

20000; 6.00000E+03 N REF:0 !

20000; 6.00000E+03 N REF:0 !

20000; 6.00000E+03 N REF:0 J

PHASE N % 1 1.0 !

CONSTITUENT N :BM,NM,SM,YM,ZM : !

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

PARAMETER

G(N,BM;0) 5.00000E+02 -50000+30"T; 6.00000E+03 N REF:0 !

G(N,NM;0) 5.00000E+02 -78000+30.29"T; 6.00000E+03 N REF:0 !

G(N,SM;0) 5.00000E+02 -50000+30"T; 6.00000E+03 N REF:0 !

G(N,YM;0) 5.00000E+02 -50000+30"T; 6.00000E+03 N REF:0 !

G(N,ZM;0) 5.00000E+02 -50000+30"T; 6.00000E+03 N REF:0 !

G(N,BM,NM;0) 5.00000E+02 -15200-7"T; 6000 N REF:0 !

G(N,BM,NM;I) 500 -13000-6.7"T; 6000 N REF:0!

G(N,BM,SM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

G(N,BM,YM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

G(N,BM,ZM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

G(N,NM,SM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

G(N,NM,YM;0) 500 -15000-7"T; 6.00000E+03 N REF:0 !

G(N,NM,YM;I) 500 13000+5"T; 6000 N REF: 0 !

G(N,NM,ZM;0) 5.00000E+02 50000; 6.00000E+03 N REF:0 !

G(N,SM,YM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

G(N,SM,ZM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

G(N,YM,ZM;0) 5.00000E+02 20000; 6.00000E+03 N REF:0 !

NASA/TM--2001-210753 13
PHASE P % 2 1 1 !

CONSTITUENT P :NM

PARAMETER G(P,NM:ZM; 0)

PHASE RB % 2 4 3 '

CONSTITUENT RB : SM :

PARAMETER G (RB, SM: ZM; 0)

REF : 0 !

: ZM : !

5. 00000E+02

ZM : !

5.00000E+02

-180450+57"T; 6.00000E+03 N REF:0 !

-557200+!71.5"T; 6.00000E+03 N

PHASE RH % 2 2 5 !

CONSTITUENT RH :SM :

PARAMETER G(RH,SM:ZM;0)

REF:0 !

ZM : !

5.00000E+02 -620000+185"T; 6.00000E+03 N

PHASE RM % 2 2 7

CONSTITUENT RM :SM :

PARAMETER G(RM,SM:ZM;0)

REF:0 !

ZM : !

5.00000E+02 -822800+258"T; 6.00000E+03 N

PHASE T % 1 1.0 !

CONSTITUENT T :BM,NM,SM,YM,ZM :

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

PARAMETER G

(T,BM; 0)

(T,NM;0)

(T,SM;0)

(T,YM;0)

(T ZM;0)

(T BM,NM; 0)

(T BM, SM; 0)

(T BM, YM; 0)

(T BM, ZM; 0)

(T NM, SM; 0)

(T NM, YM; 0)

(T NM, ZM; 0)

(T SM,YM; 0)

(T SM, ZM; 0)

(T YM, ZM; 0)

5.00000E+02

5.00000E+02

5.00000E+02

5.00000E+02

5.00000E+02

5.00000E+02

5.00000E+02

5.00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

5 00000E+02

-35000+26.462"T;

-35000+26.462"T;

-35000+26.462"T;

-35618+26.462"T;

-93955+31.755"T;

20000;

20000;

20000;

-25800;

20000;

20000;

20000;

20000;

20000;

-258O0;

6.00000E+03

6.00000E+03

6.00000E+03

6.00000E+03

6.00000E+03

6.00000E+03

6.00000E+03

6.00000E+03

6.00000E+03

6.00000E+03

6.00000E+03 N REF:0

6.00000E+03 N REF:0

6.00000E+03 N REF:0

6.00000E+03 N REF:0

6.00000E+03 N REF:0

N REF:0 !

N REF:0 !

N REF:0 !

N REF:0 !

N REF:0 !

N REF:0

N REF:0 !

N REF:0 !

N REF:0 !

N REF:0 !

LIST OF REFERENCES

NUMBER SOURCE

!

NASA/ITvI--2001-210753 14
APPENDIX II

$ MACRO bmymzm-3.tcm GENERATED ON PC/WINDOWS NT

$ Make the BM-YM-ZM ternary with a L(C,BM,YM, ZM;O)

$

go da

sw user nasa5rl

def-sys bm ym zm

get

go gib

1 -p-d

c

ent -par

L

C

bm

ym

zm

0

5O0

@? Enter Value

6000

N

go p-3

s p -op

SET MISCIBILITY GAP

c

2

bm ym

s-c n=l, t=1600, p=le5, x(ym)=.78, x(zm)=.219

l-c

c-e

s-a-s

N

Y

zm

Y

bm ym

N

N

bm

N

bm

N

DATE 0- 3- 8

term directly

NASA/TM--2001-210753 15
bm

N

bm

N

bm

N

bm

s-c n=l, t=1600, p=le5, x(ym)=.78,

l-c

c-e *

l-e

SCREEN

VWCS

s-a-v 1 x(ym)

0

1

.025

s-a-v 2 x(zm)

0

1

.O25

add

-i

li-in-eq

save

bmymzm- 3

Y

map

post

s-d-t

Y

Y

n

pl

SCREEN

ba

read

bmymzm- 3. PL3

l-c

s-c x(ym)=le-3, x(zm)=.21

l-c

c-e *

c-e

l-e

SCREEN

VWCS

add

2

li-in-eq

s-c x(ym)=.05, x(zm)=.9

l-c

c-e

c-e

l-e

SCREEN

VWCS

x(zm) =.219

NASA/TM--2001-210753 16
add

-2

li-in-eq

save

bmymzm- 3. PL3

¥

map

post

s-t-s

4

s-c-t L L

YbOl. 5

s-c-t l-r

YOI. 5

s-c-t t

ZrO2

s-f

4

0.3

s-a-t-s

x

N

X (Y01.5)

s-a-t-s

Y

N

X (ZrO2)

s-tit

YbOl. 5-YOI. 5-ZrO2 1600K

s-i -c

n

pl

SCREEN

dump

bmp

ba

read bmymzm- 3. PL3

li-in-eq

s-c x(ym)=0.78, x(zm)=0.21

l-c

c-e *

l-e

add

-I

save

bmymzm-3.PL3

Y

map

post

pl

SCREEN

set-int

ba

NASA/TM--2001-210753 17
REFERENCES

1. Y. Du, Z. Jin, and P. Huang, "Thermodynamic Assessment of the ZrO2-YO, s System," J. Am. Ceram. Soc. 74

[7] pp. 1569-77 (1991).

2. P. Duwez, F.H. Brown, Jr., and Odell, F., "The Zirconia-Yttria System," J. Electrochem. Soc. 98, pp. 356-62

(1951).

3. T. Noguchi, M. Mizuno, and T. Yamada, "The Liquidus Curve of the ZrO:-Y_O_ System as Measured by a Solar

Furnace," Bull. Chem. Soc. Japan 43, pp. 2614-16 (1970).

4. S.R. Skaggs, "The Zirconia-Yttria System above 2000 °C,'" PhD Dissertation, University of New Mexico,

Albuquerque, New Mexico, 1972.

5. K.K. Srivastava, R.N. Patil, C.B. Choudha_', K.V.G.K. Gokhale, and E.C. Subbaro, "Revised Phase Diagram

of I "the System Z "O:-YO,_, Trans. J. Brit. Ceram. Soc. 73 [2], pp. 85-91 (1974).

6. H.G. Scott, "Phase relationships in the zirconia-yttria system," J. Mat. Sci. 10, pp. 1527-35 (1975).

7. V.S. Stubican, R.C. Hink, and S.P. Ray, "Phase Equilibria and Ordering in the System ZrO.,-Y203,'" J. Am.

Ceram. Soc. 61 [1/2], pp. 17-21 (1978).

8. V.S. Stubican and J.R. Hellman, "Phase Equilibria in some zirconia systems," in Science and Technology of

Zirconia, pp. 25-36, Advances in Ceramics, Volume 3, ed. by A.H. Heuer and L. W. Hobbs, American Ceramic

Society, Columbus, OH, 1981.

9. C. Pascual and P. Duran, "Subsolidus Phase Equilibria and Ordering in the System ZrO2-Y203," J. Am. Ceram.

Soc. 66 [1], pp. 23-27 (1983).

10. R. Rub, K.S. Mazdiyasni, P.G. Valentine, and H.O. Bielstein, "Phase Relations in the System ZrO2-Y203 at Low

Y:O_ Contents," J. Am. Ceram. Soc. C-190-92 (1984).

11. V.S. Stubican, G.S. Corman, J.R. Heliman, and G. Senft, "Phase Relationships in Some ZrO2 Systems,"

pp. 96-106, Science and Technology of Zirconia II, Adv. in Ceramics, Vol. 12, ed. by N. Claussen, M. Ruhle,

and A. H. Heuer, Am. Ceram. Soc., Columbus, OH, 1984.

12. S.A. Degtyarev and G.F. Voronin, "Solution of Incorrect Problems in the Thermodynamics of Phase Equilibria.

I. The System ZrO.,-YzOs," Russ. J. Phys. Chem. 61 [3], pp. 317-20 (I987).

13. S.A. Degtyarev and G.F. Voronin, "Solution of "Incorrect" Problems in the Thermodynamics of Phase Equilibria. I. Calculation of the ZrO,-Y:O_ Phase Diagram," Russ. J. Phys. Chem. 61 [3], pp. 320-23 (1987).

14. L. Kaufman, "Calculation of Multicomponent Ceramic Phase Diagrams," Physica B 150, pp. 99-114 (1988).

15. Y. Du, Z. Jin, and P. Huang, "Thermodynamic Calculation of the ZrO:-YO,, System," J. Am. Ceram. Soc. 74

[9], pp. 2107-12 (1993).

16. Y. Du and Z. Jin, "Optimization and Calculation of ZrO_-MgO System," CALPHAD, 15 [1], pp. 59-68 (1991).

17. Z. Jin and Y. Du, "A Reassessment of the ZrO2-YO_._-MgO System," Ceramics Int. 20, pp. 17-25 (1994).

18. H. Yokokawa, N. Sakai, T. Kawada, and M. Dokiya, "Phase Diagram Calculations for ZrO: Based Ceramics:

Thermodynamic Regularities in Zirconate Formation and Solubilities of Transition Metal Oxides," Science and

Technology of Zirconia V,

19. H. Yokokawa, "Phase Diagrams and Thermodynamic Properties of Zirconia Based Ceramics," Key Engineering Materials, pp. 153-154, 37-74 (1998).

20. F.H. Brown, Jr. and P. Duwez, "The Systems Zirconium Oxide-Lanthanum Oxide and Zirconium OxideNeodynium Oxide," J. Am. Ceram. Soc. 38 [3], pp. 95-101 (1955_.

21. A. Rouanet, "Zirconium Dioxide-Lanthanide Oxide Systems Close to the Melting Point," Rev. Int. Hautes

Temp. Refract. 8 [2], pp. 161-80 (19713.

22. M.A. Clevinger, K.M. Hill, T.R. Green, C.C. Cedeno, E. Hayward, and N. Swanson, "Phase Equilbrium

Diagranas, CD-ROM Database. Version 2.1," Am. Ceram. Soc., Westerville, OH, 1993, Figure 93-023.

23. ibid. Figure 93-055.

24. ibid. Figure 5257.

25. ibid. Figure 4430.

26. ibid. Figure 4426.

27. ibid. Figure 347.

28. ibid. Figure 351.

29. ibid. Figure 5234.

ibid. Figure 5235.

G.S. Corman and V.S. Stubican, "Phase Equilibria and Ionic Conductivity in the System- ZrO2-Yb20_-Y:O_," J.

Am. Ceram. Soc. 68 [4], pp. 174-81 (1985),

H.L. Lukas, E.-Th. Henig, and B. Zimmermann, "Optimization of Phase Diagrams by a Least Squares Method

Using Simultaneously Different Types of Data," CALPHAD 1 [3], pp. 2215-36 (1977).

O. Kubachewski and C.B. Alcock, Metallurgical Thermochemistry, 5_"Edition, Pergamon Press, Oxford, 1983.

30.

31.

32.

33.

NASA/TM--2001-210753 18
34.L.V.Gurvich,V.S.Iorish,D.V.Chekhovskoi, andV.S.Yungman, IVTANTHERMO-AThermodynamic DatabaseandSoftwareSystemforthePersonal Computer, NISTSpecial Database5,NIST,Gaithersburg, MD,

1993.

35.L.B.Pankratz, "Thermodynamic PropertiesofElementsandOxides,"Bulletin672,UnitedStatesDepartment

oftheInterior,BureauofMines,1982.

36.M.Yoshimura, "PhaseStabilityofZirconia,"Am.Ceram.Soc.Bull.67[12],pp.1950-55(1988).

37.O.Redlich,A.T.Kister,andC.E.Turnquist, "Thermodynamics ofSolutions,"Chem.Eng.Progress, Syrup.

Series, 48,pp.49-64(1952).

38.R.T.DeHoff,Thermodynamics in Materials Science, McGraw-Hill, 1993.

39. M. Hillert, Phase Equilibria, Phase Diagrams and Phase Transformation Their Thermodynamic Basis,

Cambridge University Press, Cambridge, UK, 1998.

40. A.N. Belov and G.A. Semenov, "Thermodynamics of Binary Solid Solutions of Zirconium, Hafnium, and

Yttrium Oxides from High-temperature Mass Spectrometry Data," Russ. J. Phys. Chem. 59 [3], pp. 342-44

(1985).

41. A.N. Belov, G.A. Semenov, G.A. Teterin, and T.M. ShkoFnikova, "Evaporation and Thermodynamic

Properties of SqO 3 and of ZrO2-Sc203 Binary Solid Solutions According to High-temperature Mass Spectrometry Data II. Calculations," Russ. J. Phys. Chem. 61 [4], pp. 468-70 (1987),

TABLE L--AVAILABLE BINARY PHASE DIAGRAMS

ZrO: Y,O_ Yb:O_ Sc:O, Nd_O,

ZrO, x x x x

Y_O_ x x x

Yb:O_ x x

Sc,O_ x

Nci,O,

TABLE II.--ZIRCONIA AND RARE EARTH OXIDES TRANSITION TEMPERATURES

AND HEATS OF TRANSFORMATION

Oxide Phase Change T(trans) A,H A,S Reference

ZrO._ Monoclinic --_ Tetragonal

Monoclinic -+ Tetragonal

Monoclinic --_ Tetragonal

Tetragonal -_ Cubic

Tetragonal --_ Cubic

Cubic --) Liquid

Cubic --) Liquid

YaO_ Cubic ---) Hexagonal

Hexagonal --_ Liquid

Hexagonal --* Liquid

Yb_O, Cubic --_ Hexagonal

Hexagonal ---) Liquid

Nd_O_ N phase --_ Hexagonal

Hexagonal ---) Cubic

Cubic -+ Liquid

K

1448

1478

1445

2568

2620

2953

2983

2550

2712

2712

2663

2708

2333

2593

(kJ/mol)

5.941

8.075

8.4

5.9

13.001

87

90

54

81

130

125

(J/mol-K)

4.103 Kubachewski (33)

5.464 Pankratz (35)

5.813 IVTAN (34)

2.3 Kubachewski (33)

4.962 IVTAN (34)

29.492

30.171

Kubachewski (33)

IVTAN (34)

21.176 IVTAN (34)

Kubacheski (33)

29.867 IVTAN (34)

IVTAN (34)

48.006 IVTAN (34)

IV'rAN (34)

48.207 IVTAN (34)

NASAfFM--2001-210753 19
TABLE Ill.---OXIDES

AND ABBREVIATIONS

Oxide Abbreviation

ZrO, ZM

YO,._ YM

YbO_z BM

NdO, _ NM

ScO,_ SM

TABLE IV.---MOLE FRACTION OF RE_,O, IN RE.,O;ZRO,

AND EQUIVALENT MOLE FRACTION OF

RE(

Mole Fraction RE20 _

x(RE._O,)

)L.._IN REO_ cZRO.

Equivalent Mole Fraction REO,_

x(REO, _)

0.1 0.182

0.2 0.333

0.3 0.462

0.4 0.571

0.5

0.6

0.667

0.75

0.7 0.824

0.8 0.889

0.9 0.947

TABLE V.--EFFECT OFT'IRST ORDER

INTERACTION PARAMETER ON

THE LOCATION OF THE

MISCIBILITY GAP

Miscibilit)' Gap, 'L

Symmetric Zero

Shifted to Right Positive

Shifted to Left Negative

NASA/TM--2001-210753 20
2800

-- _ ._.--__ _ _.. _..Liquid Hex Y203 SS -

2400_ / \_ _

2000 -\ Cubic ZrO 2 SS / \

\ / \ Cubic

°OI-"1600 _- , _/-Tet SS't zrO2 / \ SS\ ;203

1200-_" _ / 1250o±50° _-

800 [_r_ , }_- M°n ZrO2 SS/ g \\

:: \\

t-- N

0/(a) l l l

\

0 20 40 60 80 100

ZrO2 Mol % Y203

28O0

2400

2000

oO 1600

_-" 1200

800

400

0

-"'-= "" -_. "" _ Liquid

_r- - _---'_--=------_.

Cub,cZrO2,, / _ _2_s_

_j 1o_oo_+_oo/ \\,,2o_$$

l'32s°±2s°/,o \\

o /o; _\

0 20 40 60 80 00

ZrO2 Mol % Y203

Figure 1 .--Two experimentally determined Y203-ZrO2 phase diagrams.

(a) Stubican et al. 1981 (22, 7). (b) Pascual and Duran, 1983 (23, 9).

Reprinted with permission of The American Ceramic Society, Post

Office Box 6136, Westerville, OH 43086-6136. Copyright [1984] by

the American Ceramic Society. All rights reserved.

NASA/TM--2001-210753 21
28OO

2600

2400

E

2200

2000

2825 °

Liquid

_Liq + H -'I',

o II ,2420 _\ .._._,_

Cl +,-, /,I C2

C1 C2 + H-'_ /

I C1 +02--3

/

/

_" _T /

U/// r--T + C /

It," /

H /

II /

1800 (a)

0

ZrO2

I I I I

20 40 60 80 100

Mol % Y203

2500

\

2000

? 1500!

_ FSS

E

lOOO

Tss+Fss_

_ :_2o_: _ __

500 M + FSS

.__L !

0 lO 20

/Fss +Zr3 Yb4012

/

30

S + CSS

1612 °

Zr3 Yb4012 + CSS

40 50

Mol, Yb203, % Zr3Yb4012

Figure 2.mExperimentally determined Yb203-ZrO 2 phase diagrams. (a) Rouanet

(24). (b) Stubican et al. (11). Reprinted with permission of The American Ceramic

Society, Post Office Box 6136, Westerville, OH 43086-6136. Copyright [1985]

by the American Ceramic Society. All rights reserved.

NASA/TM--2001-210753 22
?

O.

E

2000

1500

1000

800 °

+ FI ss

600 °

500 -

Mon Zr02

+

FI ss

tO

04

5

N

¢1"

-I-

,nSc2 Zr5 Ol 3 ss

+

Sc4 Zr3 012 ss

Sc4 Zr3 012 ss

Sc2 Zr7 O17 ss L_ SC2 Zr7 O17 ss

I I I

ZrO2 10 20 30 Sc4Zr3012

Mol % Sc203 -'_

Figure 3.BExpedmentally determined Sc203-ZrO 2 phase diagram

(25). Reprinted with permission of The American Ceramic Society,

Post Office Box 6136, Westerville, OH 43086-6136. Copyright

[1993] by the American Ceramic Society. All rights reserved.

NASA/TM--2001-210753 23
O.

E

\\

2600- \

2400 --

2200 -

i

2000

i

I

1800 -

/--T

r

T+C

1600 -

1400 --

0

ZrO2

\

\

/

C 1 +P

/-- Liq + Cubic

/

Liquid

r-C 2 + X

(70%)

_2060° (87%)

C2+H

r P+C2 C2+A

X

1440 °

A

O

N

04

10

z

L (50%) P. A

20 40 60 80 100

Mol % Nd203

Figure 4.mExperimentally determined Nd203-ZrO2 phase diagram (26).

Reprinted with permission of The Amedcan Ceramic Society, Post Office

Box 6136, Westerville, OH 43086-6136. Copyright [1993] by the Amedcan

Ceramic Society. All rights reserved.

NASA/I'M--2001-210753 24
_ C SS

m

] I i I

0 20 40 60 80 100

Yb203 Mol % Y203

Figure 5.DExperimentally determined Yb203-Y20 3

phase diagram (27). Reprinted with permission of

The American Ceramic Society, Post Office Box 6136,

Westerville, OH 43086-6136. Copyright [1993] by the

American Ceramic Society. All rights reserved.

_ C $$

I I I I

0 20 40 60 80 100

Y203 Mol % Sc203

Figure 6.--Experimentally determined Sc203-Y20 3

phase diagram (28). Reprinted with permission of

The American Ceramic Society, Post Office Box

6136, Westerville, OH 43086-6136. Copyright [1993]

by the American Ceramic Society. All rights reserve(

NASA/TM--2001-210753 25
H+Liq--, 2440 o

2400 - Liquid

2330° __._'_/Z _,o-,=o

__.._._."_ _ _ -z_ 2375_

×s,

? 2000L "_ "\ r _* c.,/

A ss _ _ _ "_ 1975 °'

I

B SS

/7

1600 /

/,

I

!

1400 -

0

Nd203

I B ss C ss 4"

I C ss

I

I

I

i I

I I I

20 40 60 80 100

Mol % Y203

Figure 7.--Experimentally determined Nd203-Y203 phase diagram

(29). Reprinted with permission of The American Ceramic Society,

Post Office Box 6136, Westerville, OH 43086-6136. Copyright

[1993] by the American Ceramic Society. All rights reserved.

1500 _ C SS

I I [ I

0 20 40 60 80 1 O0

Yb203 Mol % Sc203

Figure 8.mExperimentally determined Sc203-Yb203

phase diagram (28). Reprinted with permission of

The American Ceramic Society, Post Office Box

6136, Westerville, OH 43086-6136. Copyright [1993]

by the American Ceramic Society. All rights reserved.

NASA/TM--2001-210753 26
2400

2200

2000

E

1800

1600

1400

0 40 60 100

Nd203 Mol% Yb203

2435°--_

_ H + Liq ---. _j_

2330 ° Liquid 2300°--". _Z_ """_"

H SS . /////

I A_s 2__i 1940o

I /_Y

//

IJ-. . ss ess css

./ C ss

/_-- A+B

I

I

I

I I I

20 80

Figure 9.--Experimentally determined Nd203-Yb203 phase diagram (30).

Reprinted with permission of The American Ceramic Society, Post Office

Box 6136, Westerville, OH 43086-6136. Copyright [1993] by the American

Ceramic Society. All rights reserved.

oo

2000

1500 -

1000

0

Nd203

A+P P+C

I I I I

20 40 60 80 ! 00

Mol % Sc203

Figure 10.--Experimentally determined Nd203-Sc203

phase diagram (28). Reprinted with permission of The

Amedcan Ceramic Society, Post Office Box 6136,

Westerville, OH 43086-6136. Copyright [1993] by the

American Ceramic Society. All rights reserved.

NASA/TM--2001-210753 27
ZrO 2

10

1200°C

10

50

4O

/

/ /

/ /

v/

20 Fss

Fss + Zr3_ Yb)4012

/

/ t 1

Zr3(Y, Yb)4012 + Css

/ J

Iv I v_

ZrO 2

\

\

\

\

40

50

50

1(

1400 °C

10

2O

30

40

C_

Fss + Cs_ + Zr3(Y' Yb)4012

\\ Css\+ Zr 3 (_, Yb) 4 012\ \ \

Figure 11 .--Experimental determined Y203-Yb203-ZrO 2 phase diagram (31) at (a) 1200 °C, (b) 1400 °C,

and (c) 1650 °C. Reprinted with permission of The American Ceramic Society, Post Office Box 6136,

Westerville, OH 43086-6136. Copyright [1993] by the American Ceramic Society. All rights reserved.

NAS A/'rM--2001-210753 28
ZrO 2

20

10

1650 °C

\

,+ C_

50 50

Figure 11 .--Concluded. (c) 1650 °C. Reprinted with permission of The American

Ceramic Society, Post Office Box 6136, Westerville, OH 43086-6136. Copyright

[1993] by the American Ceramic Society. All rights reserved.

1000

500

? o

-500

5

-1000

÷

O4

X

__ -1500 --

o

4"

o_ -2000 --

0

0

L9 -2500

0.0

I ]

°L = 25 kJ/mol

°L = 20 kJ/mol 1L = 5 kJ/mol

°L = 20 kJ/mol 1L = -5 kJ/mol

L I

0.2 0.4 0.6 0.8 1.0

Xl

Figure 12.--Values of Gconfig + Gexcess versus T illustrating the effect of the

interaction parameters on the symmetry and location of the miscibility gap.

NASA/TM--2001-210753 29
3000

?

2500

2000

1500

1000

500

Cubic ZrO2 ss

Tet ZrO2 ss

I

0.2

Liquid

Hex YO 1.5 ss -_

o I

0.0 0.4 0.6 0.8 1.0

ZrO2 x (YO1.5) YO1.5

Figure 13.wCalculated YO1.5-ZrO2 phase diagram. Compare to Figure l(a).

The starting point for the calculation is x(YM) = 0.5, T = 3500 K.

NASA/TM--2001-210753 30
300O

2500

Liquid

Cubic ZrO 2 ss

Hex YbO1.5 ss---_

\

\

20OO

P

_1500

O

D.

E

1000

Tet ZrO 2 ss

5OO

0 I I I

0.0 0.2 0.4 0.6 0.8 1.0

Zr02 x (Yb01.5) Yb01.5

Figure 14.--Calculated YbO1.5-ZrO2 phase diagram. Compare to Figure 2.

The starting point for the calculation is x(ZM) = 0.5, T = 3500 K, followed

x(ZM) = 0.2, T = 2000 K.

NASA/TM--2001-210753 31
3000[ ZrO2"ScO1.5

2500

2000

?

1500

E

1000

500

Cubic ZrO 2 ss

f

0

0.0 0.4 0.6 0.8 1.0

ZrO2 x(ScO1.5) ScO1.5

Figure 15._alculated ScO 1.5-ZrO2 phase diagram. Compare to Figure 3.

The starting point for the calculation is x(ZM) = 0.5, T = 3500 K.

NASA/TM--2001-210753 32
3OOO

?

2500

2000

1500

1000

500

Cubic ZrO2 ss

Liquid

0 I I

0.0 0.2 0.4 0.6 0.8 1.0

ZrO2 x (NdO1.5) NdO1.5

Figure 16._alculated NdOl.5-ZrO2 phase diagram. Compare to Figure 4.

The starting point for the calculation is x(ZM) = 0.1, T = 1800 K, initially

mapping up with temperature, followed by x(ZM) = 0.99, T = 1000 K,

initially mapping up with temperature, followed by x(ZM) = 0.99, T = 3100 K,

initially mapping up with temperature, and finally x(ZM) = 0.1, T = 2300 K.

NASA/TM--2001-210753 33
3OOO

B

25_00 Liquid

_2000

O.

E

1500

Cubic

1000 [ . I [

0.0 0.2 0.4 0.6 0.8 1.0

YbO1.5 x (YO1.5) YO1.5

Figure 17._alculated YbO 1.5-YO1.5 phase diagram. Compare to Figure

5. The starting point for this calculation is x(YM) = 0.001, T = 2500 K,

map with temperature increasing first.

NASA/TM--2001-210753 34
3000

2500 -

?

2000 -

O.

E

1500 -

1000

0.0

Sc01.5

Liquid

Cubic

I I I I

0.2 0.4 0.6 0.8 1.0

x (YO1.5) Y01.5

Figure 18._alculated ScO 1.5-YO1.5 phase diagram. Compare to Figure

6. The starting point for this calculation is x(SM) = 0.001, T = 2500 K,

map with temperature increasing first.

NASA/TM--2001-210753 35
2500

2000

Liquid

Cubic ss

Hex ss

Cub ss

1500

"-I

E

lOOO

500

0 I I I I

0.0 0.2 0.4 0.6 0.8 1.0

NdO1.5 x (YO1.5) YO1.5

Figure 19.----Calculated NdO1.5-YO1.5 phase diagram. Compare to Figure

7. The starting point for this calculation is x(YM) = 0.01, T = 3000 K,

followed by x(YM) = 0.99, T = 1500 K.

NASA/TM--2001-210753 36
3000

2500

o0 2000

1500 --

1000 --

500

0.0

Y01.5

m

Liquid

Cubic ss

I I I I

0.2 0.4 0.6 0.8 .0

x (ScO 1.5) Sc01.5

Figure 20.--Calculated ScO 1.5-YO1.5 phase diagram. Compare to Figure

8. The starting point for this calculation is x(SM) = 0.001, T = 2500 K,

map with temperature increasing first.

NASA/TM--2001-210753 37
2500

2000

y Hex ss

Cub ss

1500

E

lOOO

500

0 I I I I

0.0 0.2 0.4 0.6 0.8 1.0

NdOt .5 x (YbO1.5) YbO1.5

Figure 21 --Calculated NdOl.5-YbO1.5 phase diagram. Compare to Figure

9. The s-arting point for this calculation is x(BM) = 0.99, T = 3000 K,

followe ,_ by x(BM) = 0.1, T = 1500 K.

NASA/TM--2001-210753 38
2500

200O

Liquid ------------

Cubic ss

500

I t I I

0.0 0.2 0.4 0.6 0.8 1.0

NdO1.5 x (ScO 1.5) ScO1.5

Figure 22._alculated ScO1.5-NdO1.5 phase diagram. Compare to Figure

10. The starting point for this calculation is x(SM) = 0.001, T = 3000 K,

followed by x(SM) = 0.001, T = 1000 K.

NASA/TM--2001-210753 39
A

5

1.0

0.8

0.6

0.4

0.2

_ A

A

A

A

A A

I

0.2 0.4 0.6

A

0.0 I

0.0 o.8 1.o

x (YOl.s)

1.0

0.8

0.6

0.4- A A

0.2-

A

A

0.0 (b). I i i i A A

0.0 0.2 0.4 0.6 0.8 1.0

x (YO1.5)

Figure 23.--Calculated activities across the YOI.5-ZrO2

phase diagram at 2773 K (line) and experimental data

(points) of Belov and Semenov et al. (39). This line was

generated using a starting point of x(ZM) = 0.8 and

then a step with options command. (a) a (YO1.5).

(b) a (ZrO2).

NASA/TM--2001-2 i 0753 40
5

O

1.0

0.8

0.6

0.4

0.2

J

a

a

a

a

a

a

a A

0.2 0.4 0.6

0.0 I

0.0 0.8 1.0

1.0

X (ScO 1.5)

0.4-

0.2- A

a

0.0 (b) I I I tA ^

0.0 0.2 0.4 0.6 0.8 .0

x (SCO1.5)

Figure 24._Calculated activities across the ScOl.5-ZrO2

phase diagram at 2600 K (line) and experimental data

(points) of Belov and Semenov et al. (40). This line was

generated using a starting point of x(ZM) = 0.8 and

then a step with options command. (a) a (ScO1.5).

(b) a (ZrO2).

NASA/TM--200 I-210753 41
ZrO2

1

._uj_ . ,--- Tet Zr02 + cub ZrO2

0.8 " '

0.7

\

0.3

0.2

0 A _V ..............

Yb01.5 0 0.2 0.4 0.6 0.8 1.0 YO_.s

x (YOl.s)

ZrO2

1.0 •

0.9

0.8

0.7

0.4

0.3

0.2

Yb01.5 0 0.2 0.4 0.6 0.8 1.0 YOl. 5

x (YOI.s)

Figure25.--Calculated ternarysection for the YbO1.5-YO1.5-ZrO2

systemat 1600 K. (a) L(C,BM, YM, ZM; 0) = +10 000 insufficient

to form a continuoustwo phaseregion. (b) L(C, BM, YM, ZM; 0) =

+100 000 continuoustwo phase region.

NASA/TM--2001-210753 42
YbO1.5

1.02_ Zr02

0,9 _.-'-- Tet ZrO2+ cub ZrO 2

0,8

0,7

_'P

.

0.57Y,/

o° Y

/ / / \_-_ ..--- Zr3 (Y, Yb)407

0.3

0.2

0 0,2 0.4 0,6 0.8 1.0 YO1-5

x (YO 1.5)

0._ 'o/_Z r02

0.8

0.7

o/_b) _ _ _ _

Yb01.5 0 0.2 0.4 0.6 0.8 1.0 Y01.5

x _(01.5)

1.0/_ zr02

0,9

0.8

0.7

0.6

0.2

Yb01.5 0 0.2 0.4x(Y01. Q65) 0.8 1.0 Y01.5

Figure 26.---Calculated ternary diagram for the YbO1.5-YO1.5-ZrO2

system at (a) 1473 K, (b) 1673 K, and (c) 2000 K.

NASA/TM--2001-210753 43
1.0

0.8-

¢3 0.6 -

<

t.I.

"1-

Q.

_.e

_ o.4-

0.2--

0.0

500

I

I

I

I

I

I

I

I

I

I

rC

!

T i

, ;

\

\

\ ;

I

I

I

I

tiC

I

I I .1

1500 2000 2500

Temperature, °C

Figure 27.--Calculated phase fraction diagram for

0.05_:_O1.5-0.04YO1.5-0.01 ScO1.5-0.9ZRO2.

RM

1000 3000 3500

2800

2400

?

2000

_16O0

1200

C

T

I I I

8O0

0.00 0.04 0.08 0.12

x(YM)

Figure 28._Calculated isopleth for

YbO 1.5-Y01.5-Nd01.5-Zr02 with

x(Yb01.5) = x(Sc01.5) = 0.02.

0.16

NASA/TM--2001-210753 44

REPORT DOCUMENTATION PAGE FormApproved

OMB No. 0704-0188

Public reportingburdenfor this collectionof informationIsestimatedto average1 hourperresponse,Includingthe timefor reviewingInstructions,searchingexistingdatasources,

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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

September 2001 Technical Memorandum

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Thermodynamic Database for the NdOi.5-YOi.5-YbOi.5-ScOi.5-ZrO 2 System

6. AUTHOR(S)

Nathan S. Jacobson, Evan H. Copland, and Larry Kaufman

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

John H. Glenn Research Center at Lewis Field

Cleveland, Ohio 44135-3191

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

WU-714-4)4-60-00

8. PERFORMING ORGANIZATION

REPORT NUMBER

E-12681

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA TM--2001-210753

11. SUPPLEMENTARY NOTES

Nathan S. Jacobson and Evan H. Copland, NASA Glenn Research Center; Larry Kaufman, Consultant, Brookline,

Massachusetts 02445. Responsible person, Nathan Jacobson, organization code 5160, 216--433-5498.

12a. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified - Unlimited

Subject Categories: 25 and 27 Distribution: Nonstandard

Available electronically at http://gltrs._c.nasa.gov/GLTRS

This publication is available from the NASA Center for AeroSpace Information. 301-6214)390.

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

A database for YOI.5-NdO 1.5-gbOl.5-ScOl,5-zrO2 for ThermoCalc (ThermoCalc AB, Stockholm, Sweden) has been

developed. The basis of this work is the YOi.5-ZrO 2 assessment by Y. Du, Z. Jin, and R Huang, "Thermodynamic

Assessment of the ZrO2-YO 1.5 System," J. Am. Ceram. Soc. 74, [7], pp. 1569-77 (1991 ). Experimentally only the

YO1.5-ZrO 2 system has been well-studied. All other systems are only approximately known. The major simplification in

this work is the treatment of each single cation unit as a component. The pure liquid oxides are taken as reference states

and two term lattice stability descriptions are used for each of the components. The limited experimental phase diagrams

are reproduced.

14. SUBJECT TERMS

Thermodynamics; Database; Ceramics

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