NATIONAL BUREAU OF STANDARDS REPORT

9986

Progress Report

on CRYSTAL STRUCTURE TRANSFORMATIONS IN VPt

PRODUCED BY PLASTIC DEFORMATION AT ROOM TEMPERATURE

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT

3 11.05- 11-3 110560 December 31, 1968

NBS REPORT

9986

Progress Report

on CRYSTAL STRUCTURE TRANSFORMATIONS IN VPt

PRODUCED BY PLASTIC DEFORMATION AT ROOM TEMPERATURE

by

R. M. Waterstrat*

Research Associate from the American Dental Association in the Dental Research Section, National Bureau of Standards,

Washington, D. C. 20234

This investigation was supported in part by Research Grants

D E— 00949 to the American Dental Association from the National Institute of Dental Research, and is part of the dental

research program conducted by the National Bureau of Standards

in cooperation with the Council on Dental Research of the

American Dental Association; the Dental Research Division of

the U. S. Army Medical Research and Development Command; the Dental Sciences Division of the School of Aerospace Medicine,

USAF; and the Veterans Administration.

IMPORTANT NOTICE NATIONAL BUREAU OF STAN

for use within the Government. Bel and review. For this reason, the pi whole or in part, is not authorized Bureau of Standards, Washington, t the Report has been specitically pre

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

accounting documents intended

ijected to additional evaluation

ting of this Report, either in

ffice of the Director, National

le Government agency for which

as for its own use.

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

Crystal Structure Transformations in VPt

Produced by Plastic Deformation at Room Temperature

by

R. M. Waterstrat

The phase VPt has been reported to have a crystal

structure of the B19 (AuCd) type at low temperatures. 1

* 2

A recent investigation3 has indicated that this phase forms

by an ordering reaction from the disordered face-centered

cubic Pt (V) solid solution which is stable at high temperatures. Olander4 has shown that there exists a close structural relationship between the orthorhombic B19 structure

and a face-centered cubic structure possessing the Ll c (CuAu)

type of atomic ordering. One may derive the B19 structure

by a shear-like displacement of the atoms in the (002) plane

of the ordered face-centered cubic lattice along the <010>

direction through a distance equal to one eighth of the unit

cell dimension (see Fig. 1) followed by an orthorhombic

o o distortion of the cube axes such that a = 2.693 A, b = 4.413 A

and c = 4.767A (estimated uncertainty ± 0.005A).

- 2-

Filings of this phase were produced by grinding a

VPt alloy having the B19 structure with a diamond dental

grinding disc. When these filings were subjected to x-ray

diffraction examination, a pattern of a severely cold-worked

face-centered cubic structure was obtained. When the filings

were annealed in a high vacuum furnace for 15 minutes at

1100 °C / however, they returned to the B19 structure perhaps

as a result of re-ordering. Subsequent less-severe coldworking of these filings by grinding in a hardened steel

mortar and pestle at room temperature produced a transformation into a cold-worked Ll 0 structure which was slightly

tetragonal. Thus it appears that the degree of deformation

may influence the final structure. Considerable line-broadening

was observed in x-ray diffraction patterns obtained from the

cold-worked filings and therefore no attempt was made to obtain

accurate lattice parameters. Vacuum annealing treatments at

1100°C intended for strain relief resulted in transformations

to the B19 structure.

Alloys were also prepared containing the B19 structure

in equilibrium with the face-centered cubic disordered Pt(V)

-3-

solid solution at compositions between 40 and 50 atomic per

cent vanadium by annealing in high vacuum for three days at

1300 °C. A typical microstructure of the alloy V43 PtE 7 is

shown in Fig. 2. Examination under crossed polarizers

indicated that the striations were a second phase (presumably

the B19 phase) which frequently forms initially at primary

grain boundaries and then grows toward the interior as thin

ribbons. X-ray studies on filings of this alloy re-annealed

at 1300 °C for 15 minutes indicated a strong pattern of the

face-centered cubic phase together with a substantial pattern

of the B19 phase. The unannealed filings, however, showed

only the pattern of a cold-worked, face-centered cubic structure. In these two-phase alloys it appears, therefore, that

the B19 phase is transformed into a disordered face-centered

cubic structure by cold-working. The mechanical properties

of these alloys would be of some interest since a facecentered cubic structure might be expected to possess greater

ductility than the orthorhombic B19 structure from which it

forms

.

-4-

Acknowledgment

The author wishes to thank Mr. Harvey Yakowitz and

Mr. Richard Manuszewski for obtaining the photomicrograph

in Fig. 2. This research was partially supported by

Research Grant DE- 02455 from the National Institute of

Dental Research.

References

K. Schubert , K. Frank, R. Gohle, A. Maldonado,

H. G. Meissner, A. Raman and W. Rossteutscher

Naturwissenschaften, 1963, Vol. 50, p. 41.

A. Maldonado and K. Schubert: Z. Metallkunde, 1964,

Vol. 55, pp. 619-626.

R. M. Waterstrat, Research Associate, National Bureau

of Standards, Washington, D. C.: unpublished research

(1969) .

A. Olander: Z. Krist, 1932, Vol. 83, pp. 145-148.

Figure

1.

Schematic

derivation

of

the

B19

(AuCd)

structure

from

an

ordered

face-centered

cubic

structure

by

sheer

displacement

along

the<0

10>

direction

to

be

followed

by

an

orthorhombic

distortion

of

the

cube

axes.

Legend of Figures

Figure 1. Schematic derivation of the B19

(AuCd) structure from an ordered face-centered

cubic structure by shear displacement along the

<010> direction to be followed by an orthorhombic

distortion of the cube axes.

Figure 2. The alloy V43 PtB7 annealed for

three days at 1300 °C. Thin ribbons of the B19

phase in a disordered face-centered cubic matrix

of the platinum (V) solid solution. Oblique

incident illumination. 550x

.

Figure 2. The alloy V Pt annealed for three days at 1300°C. Thin ribbons of

the B19 phase in a disordered face-centered cubic matrix of the platinum (V) solid

solution. Oblique incident illumination. 550x.