MOLYBDENUM
material properties and alloys

Molybdenum
Molybdenum is one of 90 naturally occurring elements. It has a body-centered cubic structure and is classified as a refractory
metal because of its melting point of 2620 °C.
Molybdenum and molybdenum alloys are produced either by powder metallurgy or using a molten route (electron beam or vacuum arc melting). Powder metallurgical processing has crucial advantages over the methods and is consequently widely used.
The fine-grained microstructure resulting from powder metallurgy production allows for easier further processing and improves
the mechanical properties of the final product. Additionally, the powder route is the only production option to generate alloys
such as molybdenum doped with La₂O₃ or Y₂O₃.
Plansee was founded in 1921 by Dr. Paul Schwarzkopf and is now one of the leading manufacturers of powder metallurgical materials and components. We have manufactured refractory metals and their alloys for 100 years. In addition, the Plansee productrange includes the high-melting metals tungsten, tantalum, niobium and, chromium as well as their alloys.

2

Contents
Molybdenum

Page

Production process of semifinished products

4–5

Material range and chemical specification

6–7

Basis for material selection

8 – 11DIS CLAIM ER

Properties of molybdenum and its alloys
Physical properties

12 – 13

Mechanical properties

14 – 17

Chemical behavior

18 – 21

Machining of molybdenum

22 – 24

Joining techniques

25 – 26

Surface treatment of molybdenum and its alloys

27– 29Available products and standard dimensions

30

Other Plansee high-performance materials

31

Conversion of units

32

The contents of this brochure are for general information purposes only. All information contained in this brochure, e.g. regarding
quality, material properties and purpose of use, are provided only as a courtesy and does not constitute legally binding advice.
Plansee expressly disclaims any warranty, either express or implied, and liability, in particular with respect to the accuracy, completeness or suitability of the information, its freedom from errors or that the information is free and clear of third-party rights.
All rights reserved. Text, images and graphics as well as their arrangement are subject to copyright protection and other protective laws. The content of this brochure may not be copied, distributed, modified or made accessible to third parties forcommercial purposes.

3Glass melting electrodes made of Mo

Mo spray wire

Production process of semifinishedproducts
The most important mineral for the extraction of molybde-

Raw materials for the production of molybdenum powder are

num is molybdenite (MoS₂). Another, more rarely molybde-

molybdenum trioxide and ammonium molybdate.

num-containing ore is wulfenite (PbMoO₄). The largest molybdenum deposits are located in North and South America

Both materials are converted into molybdenum powder

and in China. Molybdenite occurs as a by-product of copperby a two-stage hydrogen reduction process, which yields

extraction in Chilean copper mines.

­fine-grained metal powder of high purity (≥ 99.97%).

The ores typically contain approximately 0.5% MoS₂ andAfter screening and homogenization, molybdenum powder

must be separated from accompanying minerals by enrich-is pressed into rods and plates of various geometries andment through a flotation process. The concentrate is then ro-dimensions. This takes place using either hydraulic presses

asted, converting the molybdenum sulfide into molybdenumwith steel dies, or by isostatic pressing, in which a rubber

trioxide. Impurities are removed from the roasted concentra-

bag is filled with powder for consolidation into a compact byte either by sublimation, or by chemical treatment.

water pressure acting on all sides.

Schematic flow of the production of semifinished products

Oxide

MoO₃
Raw material

4

Reduction
Reduction

MixingMixingAlloying
Alloying

Pressing
Pressing

Sintering
SinteringForming
FormingHeat
Heat
treatment
treatment

Thereafter, sintering takes place, usually in hydrogen furnaces at temperatures in the range of 1800 °C to 2200 °C. The mechanical strength and density of the pressed compact increase during the sintering process to reach the properties necessary forfurther processing into semifinished products.
The sintered billets are then hot-worked at temperatures in the range of 1200 °C to 1500 °C using processes such as extrusion,
forging or rolling. As the degree of deformation increases, the working temperature can be reduced. In this way, forged parts,

Density % of theoreticalround bars, sheets, foils and ribbons are produced. Wires are manufactured from round bars by drawing.

100
90
80
70

60
50
40
30
20

10
0
0

10

20

30

40

50

60

Deformation %ReducedPressedSinteredWorkedIncreasing range of density during processing of refractory metals

5Material range and chemical specification
In addition to molybdenum of different purity levels, the alloys listed below are produced.

Chemical composition(information given in weight %)Material designation

Mo (pure)≥ 99.97% Mo *)TZM

Mo 0.5% Ti 0.08% Zr 0.01 – 0.04% C

MHC

Mo 1.2% Hf 0.05 – 0.12% C

Mo Lanthanum Oxide

Mo Yttrium Oxide
MoRe
MoW

ML

Mo 0.3% La₂O₃

MLR

Mo 0.7% La₂O₃(R = Recrystallized)

MLS

Mo 0.7% La₂O₃(S = Stress-relieved)

Mo-ILQ

Mo 0.03% La₂O₃(ILQ = Incandescent Lamp Quality)

MY

Mo 0.47% Y₂O₃ 0.08% CeO₂

MoRe41

Mo 41.0% Re

MoRe47.5

Mo 47.5% Re

MoW30

Mo 30.0% W*) metallic purity without W

For further details on the product range please refer to page 30.

6Chemical specification of solid metallic molybdenum (more elements on request)

Main and minor
components

ASTM B387 (361)Mo

99.97% b)

Rest

Impurities

Max. values[µg/g]

Max. values[µg/g]

TypicalGuaranteed

Al

1

10

Cr

3

20

Cu

2

20

Fe

5

20

K

6

20

Ni

1

10

50

Si

2

20

100

W

169

300

C

13

30

H

RoHS a)Max. values[µg/g]

100

100

10

N

5

10

20

O

6

40

70

Cd

1

5

100

Hg c)

1

1000

Pb

5

1000

Cr (VI)
Organic
impurities(e.g. PBB. PBDE.
PFOS. PFOA)a)Standard / EU-Directive

PlanseeMin. content [%]The presence of Cr (VI) and organic
impurities can be excluded a result of
the production process (multiple heat
treatment steps at temperatures above
1000 °C in H2 atmosphere).

1000

1000

2015/863/EU, 2011/65/EU and 2000/53/EC b) Metallic purity without W c) Initial value

The chemical composition is continuously checked by means of random sampling. The sampling inspection plan, analysis andevaluation methods are outlined in the internal instruction PSE-020-WI-003. The application of the measured values for thechemical analysis is defined in PSE-680-WI-001.
Remarks: The specified physical and chemical characteristics are disclosed without regard to measurement accuracy.

7

Mo metal powder

Basis for material selection
Correct material selection requires knowledge of the application. Important criteria may be:
Workability	Physical properties(e.g., melting point, density, electrical conductivity,		(machinability, formability, welding suitability)

thermal conductivity, thermal expansion)	Recrystallization behavior
	Mechanical properties(recrystallization temperature)(e.g., strength, creep behavior, ductility)	Chemical properties(corrosion resistance, etching behavior)

Molybdenum (Mo)
Molybdenum exhibits the following properties:
High melting point 2620 °C

Low heat capacity

Low vapor pressure

High elastic modulus

High strength at elevated temperatures	High corrosion resistance to molten glassand metals

Low thermal expansion
	Recrystallization temperature
High thermal conductivity

between 800 °C and 1200 °C

The maximum operating temperature of molybdenum is approximately 1900 °C. At temperatures higher than that, tungsten must
be used in its place. Pure molybdenum is used in many industries because of its advantageous properties. Examples include
ribbons and wires for lighting technology, semi­con­ductor base plates for power electronics, electrodes for glass melting, parts forhigh-temperature furnace construction, spray wire for the automotive industry and sputtering targets and evaporation sources forcoating technology.

A wide range of properties can be achieved from molybdenum using suitable alloy compositions and manufacturing processes. Plansee has developed several different molybdenum alloys with various property profiles. The most frequently
used materials are:8

TZM (Titanium-Zirconium-Molybdenum)
In comparison to pure molybdenum, TZM has higher
strength, a higher recrystallization temperature and improved creep strength.
This is achieved by solid solution hardening and by theformation of finely dispersed carbides and oxides. Important areas of application at high temperatures arehighly stressed parts for HIP and other high-temperature
furnaces, tools (dies for isothermal forging, hot pressing

Extrusion diesand diecasting, hot-runner nozzles) and rotating anodes
for X-ray tubes. The recommended operating temperatures are between 700 °C and 1400 °C.

MHC (Molybdenum-Hafnium-Carbon)
MHC is a particle-reinforced Mo-based alloy containing 1.2
weight % Hf and 0.1 weight % C. The presence of finely
dispersed particles imparts maximum hot strength and increases the recrystallization temperature. In comparison to
TZM, the greater thermal stability of hafnium carbide increases the application temperature by 150 °C to 1550 °C. Sui-

Different types of X-ray rotating anodes

table areas of application include metal forming and rotating
X-ray anodes.

9ML/MLR/MLS (Molybdenum-Lanthanum-Oxide)
The lanthanum oxide particles (0.3 or 0.7 weight %) in thesematerials result in the formation of a layered, fibrous structure after recrystallization annealing. This special microstructure, which is stable at up to 2000 °C (depending on the
manufacturing process), imparts excellent creep properties
and leads to higher ductility at ambient temperature, after
use at elevated temperatures. Important areas of application
are furnace parts, wire and stranded wire heating elements,
sintering and annealing boats, support wires, lead wires andML wirepins for lamps as well as evaporation coils.

Mo-ILQ (Molybdenum-ILQ)
Mo-ILQ is a micro-doped material containing 0.03 weight %La₂O₃, which was developed specifically for applications in
the lighting industry. Because of the lower doping content, it
has a higher recrystallization temperature than pure Mo, but
can be worked more easily than ML. Mo-ILQ is used both asmandrel wire in filament manufacturing and filament support
wire within the lamp.

MY (Molybdenum-Yttrium-Cerium Oxide)

MY-ESS ribbon for current lead-in throughthe quartz glass

MY is a particle-reinforced Mo alloy, containing approximately 0.47 weight % yttrium oxide and 0.08 weight % cerium
oxide. This material was developed for use in the lamp industry and, in addition to good adhesion to quartz glass, exhibits
favorable welding properties and better oxidation resistance than pure molybdenum at temperatures < 400 °C. Lamp
components such as MY-ESS ribbons for the current lead-in
and evaporation sources for thermal coating processes areimportant areas of application for MY.

MoRe (Molybdenum-Rhenium)
After alloying with rhenium, molybdenum becomes ductile attemperatures significantly below ambient temperature. MoReis used as a thermocouple wire in the standard compositions MoRe41 and MoRe47.5. It also has applications in theaero­space industry, in welded constructions as well as in the
production of cathode ray tubes.

10

Mo sputtering target

MoW (Molybdenum-Tungsten)
We improve the high-temperature characteristics and corrosion resistance of our molybdenum through the use of tungsten. MoW material containing 30 percent by weight tungsten is primarily used for the production of zinc as well as
for stirring tools in the glass industry. In addition, we use ourMoW alloys to produce sputtering targets for flat screen manufacturing. MoW layers possess enhanced etching behavior, a property which is valuable for the production of thin-film
transistors.

Seamless melting crucible and mandrels made of Mo

DUMOMET®
Our material DUMOMET® is a further development of theTable 3

core material molybdenum for special applications. It is usedin particular for components in EUV applications as well as
piercing mandrels for the production of seamless tubes.s.
DUMOMET® has isotropic properties and high ductility atroom temperature. DUMOMET® is currently produced exclusively as a non-formed semi-finished product..

The following table provides an overview of the properties of various molybdenum alloys compared with pure molybdenum.

TZM

Alloying components(in % by weight)

MHC

0.5% Ti
1.2% Hf
0.08% Zr
0.05-0.12% C
0.01-0.04% C

ML

Mo-ILQ

MY

MoRe

MoW

0.3% La₂O₃
0.7% La₂O₃

0.03% La₂O₃

0.47% Y₂O₃
0.08% CeO₂

41% Re47.5% Re

30% W

Thermal conductivity

-

-

~

~

~

-

-

Stability atroom temperature

+

+

~

~

~

+

+

High-temperaturestability /Creep resistance++(< 1400 °C)+(> 1400 °C)++(< 1500 °C)+(> 1500 °C)+(< 1400 °C)++(> 1400 °C

+

+

+

+

Recrystallization
temperature

+

++

++

+

+

+

+

Ductility after
HT use

+

+

++

+

+

++

~

Weldability

+

+

+

+

+

++

~

~ comparable with pure Mo + higher than pure Mo ++ much higher than pure Mo - lower than pure Mo

11

Properties of molybdenum and its alloys
Physical properties

Properties
Atomic number

42

Atomic mass

95.94 [g/mol]

Melting point

2620 °C

Boiling point4639 °C

Atomic volume0.0153 [nm³]Density at 20 °C

10.22 [g/cm³]

Crystal structure

Body-centered cubic

Lattice constant

315 [pm]

Linear coefficient of thermal expansion at 20 °C

5.2 × 10-6 [m/(m•K)]

Thermal conductivity at 20 °C

142 [W/(m•K)]

Specific heat at 20 °C

0.25 [J/(g•K)]

Electrical conductivity at 20 °C

17.9 × 106 [S/m]Specific electrical resistivity at 20 °C

0.056 [(Ωmm2)/m]

Acoustic velocity at 20 °C

Longitudinal wave

6250 [m/s]Transverse wave

3350 [m/s]Electron work function

4.39 [eV]

Capture cross-section for thermal neutrons

2.7 × 10-28 [m²]Gobbing stirrer with MoW shaft

12

Vapor pressures of refractory metals in high vacuum

Evaporation rates of refractory metals under high vacuum

Linear thermal expansion coefficient of Mo and TZM
as a function of the temperature

Thermal conductivity of Mo and TZM
as a function of the temperatureSpecific electrical resistance of TZM and Mo/MLR
as a function of the temperatureSpecific heat of Mo and TZM
as a function of the temperature

13

Mechanical properties
Because of its high melting point in excess to 2620 °C, molybdenum retains its strength and creep resistance up to hightemperatures. The mechanical properties are influenced by the purity, type and composition of any alloying elements as well
as by the microstructure.
As is the case with all other metals, an increase in strength is observed with increasing deformation. However, in contrast to
most other metals, the ductility of molybdenum also increases as deformation increases. A further option of increasing ductility
is to reduce the ductile-to-brittle transition temperature by alloying with rhenium.
Properties such as strength, ductility, creep resistance and machinability can be adjusted ideally by alloying with small amountsof titanium, zirconium, hafnium, carbon, rhenium or with oxides of lanthanum, yttrium and cerium. The molybdenum alloy selected for a given application may depend on the operating temperature and the design of the product.
The ductility as well as the fracture toughness of molybdenum alloys decrease with increasing levels of recrystallization. Typicalrecrystallization temperatures of molybdenum-based alloys are listed in the table above. The particle-reinforced materials, inparticular ML, exhibit a strong increase in the recrystallization temperature with increasing deformation, caused by progressive
particle refining.

14

Material

Temperature °C for 100% recrystallization(annealing duration 1 hour)
ϕ = 90%ϕ = 99,99%

Mo (pure)

1100

TZM

1400

MHC

1550

ML

1300

2000

Mo-ILQ

1200

1600

MY

1100

1350

MoRe41

1300

MoW30

1200

ϕ = degree of deformation

Young’s modulus of molybdenum as a function of the temperature compared to refractory metals such as tungsten,tantalum, niobium and chromium. The molybdenum alloys TZM, MHC, ML and MY have a Young’s modulus comparable to pure molybdenum.

15

Typical 0.2% proof stress for Mo and TZM sheet material in
the stress-relieved and recrystallized condition, respectively(thickness of the sheet: 2 mm)

Typical ultimate tensile strength for Mo and TZM sheet material
in the stress-relieved and recrystallized condition, respectively(thickness of the sheet: 2 mm)

Comparison of the steady-state creep rate of Mo, TZM and MLR
sheet material at 1100 °C

Comparison of the steady-state creep rate of Mo, TZM and MLR
sheet material at 1450 °C and 1800 °C

Description of the sample material for the creep tests

Material

Mo

TZM

MLR

16

Testing temperature[°C]

Thickness of sheet
material [mm]Heat treatment
before the test

1100

1.5

1200 °C / 1 h

1450

2.0

1500 °C / 1 h

1800

6.0

1800 °C / 1 h

1100

1.5

1200 °C / 1 h

1450

1.5

1500 °C / 1 h

1800

3.5

1800 °C / 1 h

1100

1.5

1700 °C / 3 h

1450

1.0

1700 °C / 3 h

1800

1.0

1700 °C / 3 hOptical micrograph of a Mo sheet metal(stress-relieved)

Optical micrograph of a Mo sheet metal(recrystallized)

Optical micrograph of a MLR sheet metal

Typical 0.2% proof stress for Mo, TZM and MHC bar material(diameter 25 mm; stress-relieved condition)

Typical ultimate tensile strength values for Mo, TZM and MHC
bar material (diameter 25 mm; stress relieved condition)

Hardness values for Mo, TZM and MHC bar material(diameter 25 mm, stress-relieved condition) as a function of
the temperature17

Chemical behavior
Molybdenum and its alloys exhibit very similar corrosion behaviors and will therefore not be treated individually in the following
section. Due to the high content of alloying elements, MoRe alloys behave significantly differently under various corrosive conditions. For detailed questions regarding MoRe alloys, please contact us for individual tests.
When studying corrosion properties, important factors include not only the material itself, but also system parameters such astemperature, oxygen content, agitation and flow rates, etc.. It is therefore important to understand the resistance to corrosion
as a system property, and not as a material property. The data shown here serves as a rough guideline for the application ofmolybdenum and its alloys. We recommend carrying out corrosion tests under simulated application conditions.
In the temperature range of 5 °C to 30 °C and at a relative humidity level of < 60%, molybdenum is resistant to atmosphericcorrosion. Above that, superficial oxidation may occur, resulting in discoloration. This discoloration is caused by a very thinoxide layer a few nanometers thick. While this thin oxide layer is visible to the human eye, it does not influence the mechanicalproperties of the part. Figure 1 shows a molybdenum surface after exposure to air for 168 h at 98% relative humidity at 40 °C.
In aqueous media, molybdenum is resistant to reducing environments and attacked by oxidizing agents. Therefore, acids suchas HCl or HF do not attack the metal, while exposure to HNO₃, for example, leads to quick dissolution of the metal. Diluted
alkaline solutions, such as NaOH or KOH solutions, do not attack molybdenum and its alloys.
Even at very high temperatures up to the melting point, molybdenum and its alloys react neither with inert gases, such as nitrogen,helium and argon, nor with hydrogen. Only the oxygen partial pressure and dew point of the gas must be controlled. Oxidation in
air starts at a temperature as low as 250 °C. At 400 °C, strong oxidation occurs, and a dark layer is formed on the surface. Above
Table 1600 °C, sublimation of MoO₃ results in material losses and needs to be avoided. Calculated as well as experimental data is available to quickly estimate mass loss rates as a function of the temperature and oxygen partial pressure. Figure 2 shows molybdenum
surfaces after exposure to air for 1 h at 200 °C, 300 °C, 400 °C, 500 °C and 600 °C.
Molten glass, many molten metals and ceramic oxides do not attack molybdenum at all, even at very high temperatures, provided they are free of oxidizing agents.
The table below shows the chemical behavior of molybdenum and its alloys towards selected media. It is not recommended touse molybdenum in media denoted by (-). It is however possible to improve resistance by coating molybdenum parts with othermaterials, by applying metallic or ceramic coatings, for example using electroplating or thermal spraying techniques.
Plansee performs corrosion tests for our customers under standardized conditions, such as salt spray tests (ASTM B117, DIN
EN ISO 9227), climate chamber tests and heat soak tests, as well as tests under simulated application conditions for special
environments upon request.

18

Corrosion behavior of molybdenum towards water,acids, lyes, halogens, non-metals, gases, melts and furnace construction materials
MediumResistant (+), Non-Resistant (-)

Notewater, cold and warm < 80 °C+

discolorationwater, hot > 80 °C, deaerated+

discoloration

steam up to 600 °C+

discoloration

Hydrofluoric acid (HF)+

< 100 °C

Hydrochloric acid (HC)l+

Phosphoric acid (H₃PO₄)+< 270 °C

Sulfuric acid (H₂SO₄)+< 70%, < 190 °C

Nitric acid (HNO₃)-

dissolution

Aqua regia (HNO₃ + 3 HCl)-dissolution

Organic acids

+

Water

Acids

Lyes
Ammonium hydroxide (NH₄OH)+

Potassium hydroxide (KOH)+< 50%, < 100 °C

Sodium hydroxide (NaOH)+< 50%, < 100 °C

Fluorine (F₂)-

strong attack

Chlorine (Cl₂)+< 250 °C

Bromine (Br₂)+< 450 °C

Iodine (I₂)+

< 450 °C

Boron (B)+

< 900 °C

Carbon (C)+< 900 °C

Silicon (Si)+< 550 °C

Phosphorus (P)+< 800 °C

Sulfur (S)+< 440 °C

Ammonia (NH₃)+< 900 °C

Carbon monoxide (CO)+< 1000 °C

Carbon dioxide (CO₂)+< 1100 °C

Hydrocarbons+< 1000 °C

Air and oxygen (O₂)+< 400 °C, discoloration

Inert gases (He, Ar, N₂)+

Hydrogen (H₂)+

Water vapor+

Halogens

Non-metals

Gases*< 600 °C, discoloration* Special attention must be paid to the dew point of the gas. Moisture can lead to oxidation.

19

Corrosion behavior of molybdenum towards water,acids, lyes, halogens, non-metals, gases, melts and furnace construction materials
MediumResistant (+), Non Resistant (-)

Note

Molten glass*+< 1700 °C

Aluminum (Al)-Beryllium (Be)-Bismuth (Bi)+< 1430 °C

Cesium (Cs)+

< 870 °C

Cerium (Ce)+

< 800 °C

Chromium (Cr)-

Copper (Cu)+Europium (Eu)+

Gallium (Ga)+Gold (Au)+

Iron (Fe)-

Lead (Pb)+< 1100 °C

Lithium (Li)+< 1425 °C

Magnesium (Mg)+

< 1000 °C

Mercury (Hg)+

< 600 °C

Nickel (Ni)-Plutonium (Pu)+

Potassium (K)+< 1200 °C

Rubidium (Rb)+

< 1035 °C

Samarium (Sm)+Scandium (Sc)-Silver (Ag)+< 1020 °C

Sodium (Na)+< 1020 °C

Tin (Sn)+< 550 °C

Uranium (U)-Zinc (Zn)**

-

Melts

* Except glasses with oxidizing agents; ** MoW30 alloy exhibits excellent corrosion resistance to Zn melt20

< 1300 °C< 400 °C

Corrosion behavior of molybdenum towards water,acids, lyes, halogens, non-metals, gases, melts and furnace construction materials
MediumResistant (+), Non-Resistant (-)

Note

Aluminum oxide (Al₂O₃)+< 1900 °C

Beryllium oxide (BeO)+< 1900 °C

Graphite (C)+< 900 °C

Magnesite (MgCO₃)+< 1600 °C

Magnesium oxide (MgO)+< 1600 °C

Silicon carbide (SiC)+< 550 °C

Zirconium oxide (ZrO₂)+< 1900 °C

Furnace construction materials

Figure 1: Molybdenum surface after exposure to air for 168 h
at 98% relative humidity at 40 °C

Figure 2: Molybdenum after exposure to air for 1 h
at 200 °C / 300 °C / 400 °C / 500 °C / 600 °C

21

Sintering boats made of molybdenum (furnace accessories)

Seamless crucible made of molybdenum

Machining of molybdenum
Molybdenum is considered easy to machine. However, it is important to take its properties into account during all machining
steps. Knowledge of these properties and observation of the following recommendations are necessary to successfully machine
molybdenum.

Transition temperature
Similarly to all metals that have a body-centered cubic lattice structure, molybdenum has a temperature threshold below which it
is too hard and brittle for mechanical forming. Once heated above this temperature, molybdenum loses its brittleness and becomes ductile. The so-called brittle-ductile transition temperature depends on the chemical purity and the amount of prior working.

Recrystallization temperature
Whenever molybdenum is annealed, stress-relieved or heated in preparation for hot working, as well as when it is used at hightemperatures, an additional temperature threshold must be taken into account. Heating molybdenum and its alloys to above theirrecrystallization temperatures results in a new grain structure, which is associated with a reduction in strength and hardness. The
material’s susceptibility to cracking also increases and can only be eliminated by further mechanical working processes, suchas rolling, swaging and drawing. The recrystallization temperature of molybdenum is highly dependent on the degree of deformation in the material and its chemical composition. Finely distributed dispersoids are effective in increasing the recrystallization
temperature, as is the case with doped molybdenum, which additionally retains its ductility after recrystallization.

Mechanical working
Mechanical working must be carried out above the ductile-to-brittle transition temperature. Forming processes such as press
brake folding of sheets or bending of rods are possible after short, localized heating. Gas flame and induction heating are bothsuitable, ideally to reach red heat for the shortest time possible, and only while deformation is taking place.
Texture is an important factor when deep drawing sheet material. Specially produced, cross-rolled sheets (deep-drawing quality)
are ideal. The preheating temperature before deep drawing depends on the sheet thickness and the degree of deformation thatis required.

Cutting and stamping
Molybdenum is ideally suited for cutting and stamping. However, cracks can result from blunt cutting edges in shears and upper
punches or from insufficient pre-heating of the material. Molybdenum sheets with a thickness of less than 0.25 mm can be cut
without heating. Above this thickness, preheating to the temperature range shown is recommended.

Grinding
Particularly suitable grinding discs are those made from silicon carbide with an open structure, hardness in the H, I, J and K
range, and a grain size of 60 to 120, operating at a grinding speed of 1800 m/min and a feed rate not exceeding 0.02 mm. Recommended cooling agents are the same as those used for machining with hard metal and HSS tools.

22

Molybdenum-based alloys are all suitable for machining. Ma-

Temperature [°C]

Machining

1000

800

chine tools should be robust, and both the workpieces andthe tools should be short and firmly clamped. Many years ofexperience have enabled our CERATIZIT division to develop

600

400

grades of hard metal that are especially suitable for machining molybdenum and its alloys. For turning and milling, we

200

recommend tools fitted with CERATIZIT H 216 T or H 210 T
hard metal tips. At low cutting speeds, high-speed steel tools

0
0

2

4

6

can be used. Cooling with emulsion is essential with both

8

10

Thickness of sheet material [mm]Mo

hard metal and HSS.

Recommended temperature range for the mechanical workingof molybdenum

Recommended conditions for the machining of molybdenum and its alloys

Turning
Tools

CERATIZIT Maxilock-S

Indexable carbide inserts

Use with Code-27 and -25, HM grade H 216 T / H 210 T

Cutting speed [m/min]vc = 100 – 140

Feed [mm/rev]

f = 0.05 – 0.35 (acc. to corner radius)

Depth of cut [mm]ap = 0.3 – 6 (acc. to type of insert)

Coolant

Emulsion
Milling

Use CERATIZIT milling cutters with hard metal indexable inserts of the following cutting geometry
Rake angle γ≥ + 10°

Inclination angle

0 – 10°HM grade

H 216 T / H 210 T

Cutting speed [m/min]vc = 100 – 150

Feed [mm/tooth]f = 0.03 – 0.10

Coolant

Emulsion
HSS tools

Cutting speed [m/min]vc = 20 – 25 m

Rake angle γ≥ + 10°

Coolant

Emulsion
Drilling

Drill diameter up to 18 mm
Drill diameter up to 18 mm

HSS (if possible with internal cooling channel)

Cutting speed [m/min]vc = 10 – 15

Feed [mm/rev]

f = 0.05 – 0.1

Coolant

Emulsion
23

Joining techniquesMore complex molybdenum components can be manufactured by using a variety of joining techniques. Joining can be achievedby brazing using inert gas or vacuum furnaces, provided suitable equipment is available. Whenever the joined areas are to be
subjected to higher mechanical stresses, methods such as folding, riveting and bolting should be used, because molybdenum
has limited suitability for welding.

Welding
Molybdenum and its alloys can be fusion welded by GTAW (Gas Tungsten Arc Welding) and LBW (Laser Beam Welding)under a shield gas atmosphere of Ar or He, or by EBW (Electron Beam Welding) in vacuum with and without filler materials.
Because the ductility of the weld zone is sharply reduced by the presence of even the smallest quantities of oxygen andnitrogen, contact with air during welding must be avoided. GTAW should be carried out in a welding chamber. In pressure
welding procedures, a weld zone with high plastic deformation occurs, which benefits the resulting microstructure and theweld properties. FW (Friction Welding) would therefore be favorable for rotationally symmetric parts, and RSW (Resistance
Spot Welding) for small parts. Welding is not recommended for highly stressed components due to reduced strength anddanger of embrittlement of the weld zone.
Before welding, all parts must be carefully cleaned to remove all surface contaminants. Joint design and welding strategy haveto be selected so as to minimize internal stresses in the weld zone. As a result, preheating and stress-relief annealing after
welding are recommended. Thick-walled weld designs as well as large differences in sections of the parts should be avoided.

24

Brazing
Brazing is a widely employed method for joining molybdenum parts. Where the design permits, both similar and dissimilar materials can be brazed together (e.g., refractory metals, steels, non-ferrous metals, graphite, ceramics) to achieve favorable tensile
properties. Furnace brazing with inert gas or vacuum as well as high-frequency induction brazing are standard processes. Small
brazed joints are relatively simple to produce with brazing filler under inert gas using RSW (Resistance Spot Welding) equipment.
Brazing procedures that involve exposure to the atmosphere are not suitable because they result in surface oxidation of molybdenum.
Depending on the brazing temperature and the materials to be joined, the following brazing materials are used:	Au-Cu-based brazing alloys for temperatures up to 1000 °C
	Ni and precious metal brazing alloys for temperatures up to 1400 °C
	Ti-based, Zr-based, Ru-based and Pt-based alloys for high temperatures up to 2000 °C

Riveting, fastening and folding
The simplest method of joining is fastening by bolts or screws, for which various dimensions and thread forms are available.
Screwed joints are highly suitable for repair work. However, after molybdenum has recrystallized, there is always a risk of breakage when carrying out repairs in this manner. For riveting, both button head and countersunk rivets are available. After drilling,
the rivet holes must be cleanly deburred. Both the rivets and the riveting tool should be preheated to optimize joint strength.
Before folding, molybdenum sheets should be heated to above their transition temperature, which depends on the amount ofprior working and the material thickness.

25

Surface treatment ofmolybdenum and its alloys
Because of the similar behavior that molybdenum and its alloys exhibit, they are not treated individually in this section.

Cleaning
Molybdenum is best cleaned in alkaline aqueous solutions containing detergents (pH ≥ 10). Applying ultrasonic agitation forseveral minutes is recommended. Subsequent rinsing in high-purity water (σ ≤ 10 μS/cm), followed by drying in warm air, results in clean metallic surfaces. Thin molybdenum oxides can also be reduced by annealing in a dry hydrogen atmosphere at
approximately 800 °C.

Storage
Humid conditions and fluctuations in temperature can cause discolorations due to superficial oxidation. Molybdenum should therefore always be stored under dry conditions (relative humidity ≤ 60%) at a controlled temperature in the range of 20 °C to 30 °C.
Surface oxidation can also be prevented by using Al-coated bags, which provide a moisture vapor barrier.

Pickling
Heavily oxidized molybdenum can be cleaned in molten sodium hydroxide containing an oxidizing agent (e.g., sodium nitrate)in the temperature range of 400 °C to 450 °C. The material must be dry to avoid fast evaporation of water droplets causing
melt splashing. After cooling, any remaining pickling residues are removed by immersion in warm water. Molten salt pickled
or lightly oxidized molybdenum parts can be acid pickled to achieve a bright finish. A typical acid pickling solution contains a
mixture of nitric acid (53 weight %) and sulfuric acid (87 weight %), mixed at a 1:4 ratio by volume. Residual pickling solution isrinsed off in consecutive water and high-purity water baths, followed by drying in warm air, leading to a bright, metallic finish.

26

Surface finish
Plansee offers parts made of molybdenum and its alloys in different surface finishes.
		
Pickled: Uniform matte appearance, free from impurities as a result of a chemically cleaned surface. The pickled surfa-

ce is preferable for all standard applications in which a bright finish is not necessary. It is the least expensive variant for
sheet material.
	Ground: The appearance of ground sheets ranges between that of bright and pickled sheets. The sheets have asatin-like finish. The ground surface is a less expensive alternative to the bright surface and is suitable for all standard
applications. It is possible to work to very narrow tolerances in the case of rods that have a ground surface.
		Bright: The mirror finish is visually appealing and exhibits a high level of reflectivity that can be of interest for certain

applications (e.g., reflectors).
		Forged: The forging marks are visible on parts. Products have a matte appearance due to chemical cleaning. This is

the least expensive surface finish for rods. Forged rods are used in the glass industry and have the advantage of reduced wear compared with machined surfaces.
		Turned: Turned parts have a uniform surface with a matte appearance. Surface roughness and tolerances in the rangeof tenths of a millimeter are achieved.
		Electropolished: Electrochemical dissolution of a few microns on the surface leads to a bright appearance with

reduced roughness. Remaining particles from mechanical machining are removed from the surface. This is especiallyadvantageous in high-purity applications, e.g., in the semiconductor industry. Molybdenum is typically electropolishedin 80 wt.% sulfuric acid solution at 50 °C. Current density is in the range of 15 to 50 A/dm². The figures below shows
SEM micrographs of molybdenum in the as-machined state compared to an electropolished molybdenum surface.
		Sand blasting: Surfaces can also be sand-blasted with alumina upon request to ensure a rough surface with a matteappearance.

SEM micrographs of molybdenum surfaces as machined (left) and electropolished (right).

27

Coatings
Plansee offers various coatings on molybdenum components to enhance their properties. Upon request, Plansee assists you
with finding custom solutions for your needs. Depending on the application, available coatings range from metals to ceramics,
including, but not limited to:	For protection against atmospheric corrosion and as a surface layer to assist brazing:
Nickel, chromium and noble metals-based coatings	For protection against oxidation in air up to 1650 °C:
Silicide coatings (SIBOR®) – a cross-section of a coated part is shown in Figure 5.
Figure 6 shows an oxidation test at 1300 °C comparing a SIBOR®-coated molybdenum part to MoSi₂
	Surface hardening for wear protection:
Gas phase nitriding (SHN), carburizing or boronizing – Figure 3 shows hardness profiles of molybdenum
measured by nanoindentation after surface hardening	As a diffusion barrier and protection against corrosive environments:
Oxide coatings – an Al₂O₃-coated molybdenum stirrer is shown in the image below.
	To increase thermal emittance:
Metals-based, porous sintered coatings can be applied to molybdenum. Figure 4 shows the forecast surface
temperature for a ball-shaped sample with Ø 10 mm and a core temperature of 2000 °C depending on the surface
emittance. The surface temperature decreases with increased thermal emittance.

AI₂O₃-coated Mo stirrer

28

Predicted surface temperature [°C]

Hardness [GPa]

30

25

20

15

1990

1980

1970

1960

1950

1940

10
1930

5
1920

1910

0
5

10

15

20

25

30

35

40

45

50

55

60

65

70

0

0,2

0,4

boronizing

0,6

0,8

1

Surface emittance [-]Distance from the surface [µm]nitridingFigure 3: Hardness measured by nanoindentation vs. thedistance from the surface after hardening

Figure 4: Predicted surface temperature for a ball-shaped sample
with Ø 10 mm, core temperature 2000 °C

The typical coating thickness ranges from 0.1 to 300 µm and depends on the application. Thermal spraying techniques, suchas atmospheric plasma spraying (APS), vacuum plasma spraying (VPS) and cold-gas spraying (CGS), physical vapor deposition(PVD), suspension-based coatings and gas phase hardening, are all processes employed by Plansee. For galvanic coatings, werely on our network of trusted suppliers.

Figure 5: Cross-section of Sibor®-coated molybdenum toincrease oxidation resistance

Figure 6: Oxidation test at 1300 °C of MoSi₂ andSibor®-coated molybdenum

29Ava i l a b l e p rod u c t s an d standard dim e ns ions
Overview of the Plansee semifinished products made of Mo and Mo alloys
Sheets and plates[thickness]

Rolled sheets and ribbons[thickness]Rods[diameter]Wires[diameter]Mo

0.05 - 50 mm

Sheet: 0.100 - 0.381 mm
Ribbon: 0.015 - 0.762 mm

0.3 - 210 mm

0.015 - 3.17 mm

TZM

0.30 - 50 mm

1.0 - 165 mm
10 - 165 mm

MHC
MLS /
MLR

MLS: 0.20 - 1.0 mm
MLR: 1.0 - 50 mm

MLS sheet: 0.254 - 0.381 mm
MLS ribbon: 0.100 - 0.762 mm
0.3 - 100 mm

ML

0.200 - 3.17 mm
0.015 - 3.17 mm

Mo-ILQ
0.015 - 0.200 mm

MY
MoRe41 /MoRe47.5

Upon request

MoW30

Upon request

We strive to make life easy and have created a quick and simple order process and clearly outlined
price scales – available to you directly on your screen. Sheets, rods, ribbons and wires as well as otherproducts made of molybdenum and molybdenum alloys are available in configurable dimensions at
www.plansee.com/shop

Please visit www. plansee.com or contact your Plansee partner for more dimensions and further information on semi-finishedproducts and formed parts.

30

O th e r P l a n s ee h i gh-p e r f o r m an ce m ate r ials
Based on our many years of experience in the field of powder metallurgy, we supply a wide range of products made from highperformance materials. In addition to molybdenum and its alloys, Plansee is also a leading producer of:	Tungsten and W alloys
	Tantalum and Ta alloys
	Niobium and Nb alloys
	Tungsten-based metallic matrix composites (W-MMC)
Sputter materials for hard coating

Selection of Plansee products made of high-performance materials:

Sputtering targets

Semiconductor base plates

CuCr contacts

Glass melting electrodes

Wires for the lighting industry

Various finish types of X-ray rotary anodes

31

Conversion of units
Table 10

Property

SI UnitAream2

Densitykg/mConversation factor

3

J = N•m= W•sEnergyForce

N = kg • m/s2

Length

m

Mass

kg

Power

W = J/s

Pressure (Stress)

Pa = N/m2

Specific Heatby Mass

J (kg • K)

1 in²

= 6.4516 • 10-4 m²

1 ft²= 9.2903 • 10-2 m²

1 lb/in³= 2.76799 • 104 kg/m³

1 lb/ft³= 16.0185 kg/m³

1 Btu= 1.05506 • 103 J

1 cal= 4.184 J

1 eV= 1.6022 • 10-19 J

1 lbf= 4.4482 N

1 in= 2.54 • 10-2 m

1 ft= 3.048 • 10-1 m

1 lb= 4.5359 • 10-1 kg

1 Btu/hr= 2.93071 • 10-1 W

1 hp= 7.457 • 102 W

1 atm= 1.01325 • 105 Pa

1 lbf/in² (psi)= 6.89476 • 103 Pa

1 lbf/ft²= 47.8803 Pa

1 mbar= 102 Pa

1 N/mm² (MPa)= 106 Pa

1 torr

= 1.33322 • 102 Pa

1 cal/(g • °C)= 4.1868 • 10³ J/(kg • K)

1 Btu/(lb • °F)= 4.1868 • 103 J/(kg • K)

x °C = (x + 273.15) K
y °F = (y • 0.5556 + 255.37) K
Temperature

K (Kelvin)°F in °C: (°F – 32) • 5/9 = °C
°C in °F: (°C • 9/5) + 32 = °F

32

Thermal Conductivity

W/(m • K)

Volume

m3

°F 32

200

400

°C 0

100

200

600

300

800

400

1000

500

1 kcal/(m • hr • °C)= 1.163 W/(m • K)

1 Btu/(ft • hr • °F)= 1.73073 W/(m • K)

1 in³

= 1.63871 • 10-5 m³

1 ft³= 2.83168 • 10-2 m³

1200

600

1400

700

800

1600

900

1800

1000

2000

2200

1100

1200

2400

1300

2600

1400

1500

Close to the customer – our global network
Plansee manufactures and markets its products worldwide. Production sites in Europe, the USA, Japan, India, China, and Korea
as well as a global network of sales subsidiaries and sales partners enable outstanding customer service and product quality
delivered by local teams. Stronger than any alliance and more diversified than single producers, Plansee is the most reliable
source for high-performance components made of refractory metals.

For more information and local contacts, please visit our website:www.plansee.com

Plansee SE
Metallwerk-Plansee-Str. 71
6600 Reutte
Austria
Telephone: +43 5672 600 0
E-Mail: info@plansee.com
We reserve the right to make technical changes for improvement of the product.
Edition: 08.2023

Part of the Plansee GroupQM1 / HPM-070-TD-026 / part 000 / Version 01