Alloys with Carbide Dispersoids

Hafhium carbide (HfC) is the most potent strengthener for tungsten at elevated temperatures [6.4]. Particle size and interparticle spacing must be small in order to lead to 

FIGURE 6,12. Yield strength and ultimate tensile strength of a W-3.6Re-0.26HfC alloy as a function of temperature, in comparison to unalloyed W, W-3.6Re, and W-3.6Re-lTh02 [6.20], 

Significant strengthening is observed up to 2700 K (2427 °C). Above this, rapid particle coarsening occurs, and the strengthening effect fades. Additions of rhenium provide ductility at low temperatures by decreasing the DBTT. 

W-Re-HfC alloys cannot be produced by powder metallurgical techniques owing to the high oxygen affinity of hafnium. They are produced by arc melting. 

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