Toughness variation with test temperature and

A two phase heavy alloy composite based on 95 W-3.5 Ni-1.5 Fe (wt pct) was fabricated from elemental powders by liquid phase sintering. Past reports on the heavy alloys indicate considerable disagreement concerning cooling rate effects on toughness. The present experiments determined the effect of both cooling rate and test temperature on the properties of the 95 W heavy alloy. This alloy undergoes a ductile to brittle transition with decreasing test temperature; the transition temperature is close to room temperature. The cooling rate from post-sintering anneals carried out at temperatures greater than 1000 °C has a large influence on toughness; rapid quenching gives superior toughness. These findings support an impurity segregation explanation for embrittlement in the heavy alloys.