The molybdenum alloy of greatest technological importance is the high-strength, high-temperature alloy TZM. The material is manufactured either by P/M or arc-cast processes.
TZM has a higher recrystallization temperature and higher strength and hardness at room and at elevated temperatures than unalloyed molybdenum. It also exhibits adequate ductility. Its superior mechanical properties arc due to the dispersion of complex carbides in the molybdenum matrix. TZM is well suited to hot work applications because of its combination of high hot hardness, high thermal conductivity, and low thermal expansion to hot work steels.
Major uses include:
Die inserts for casting aluminum, magnesium, zinc, and iron
Rocket nozzles
Die bodies and punches for hot stamping
Tools for metalworking (due to the high abrasion and chatter resistance of TZM)
Heat shields for furnaces, structural parts, and heating elements
In an attempt to improve the high-temperature strength of P/M TZM alloys, alloys have been developed in which titanium and zirconium carbide is replaced by hafnium carbide. Alloys of molybdenum and rhenium are more ductile than pure molybdenum. An alloy with 35% Re can be rolled at room temperature to more than 95% reduction in thickness before cracking. For economic reasons, molybdenum-rhenium alloys are not widely used commercially. Alloys of molybdenum with 5 and 41% Re are used for thermocouple wires.
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