Microstructure, grain growth behavior and mechanical properties of W-CoCuFeNi tungsten heavy alloys prepared by infiltration

W-CoCuFeNi tungsten heavy alloys (WHAs) were fabricated by infiltration at the temperature range of 1440-1560 degrees C. The microstructure, grain growth behavior and mechanical properties of the WHAs were investigated in this study. The XRD and SEM results showed that the WHAs consisted of rounded W grains distributed in CoCuFeNi high entropy alloy (HEA). In addition, M6W6C (M = Co, Fe)-type eta carbides appeared in the interfacial regions of W grains and CoCuFeNi HEA. The W grain size and W-W contiguity were found to increase with increasing sintering temperatures. The activation energy for W grain growth in CoCuFeNi binder matrix was about 367 kJ/mol, which was far higher than that of traditional W-Ni-Fe and W-Ni-Co WHAs. This suggested that W grain coarsening rate in CoCuFeNi HEA was slower than that in traditional binder alloys. For compressive mechanical properties, the yield strength of WHA sintered at 1440 degrees C reached the highest due to the smallest W grains. The compressive ductility of W-CoCuFeNi sintered at 1560 degrees C was the worst due to increased W-W contiguity. The bending tests of W-CoCuFeNi WHAs showed that the WHA sintered at 1440 degrees C also exhibited the highest bending strength. From the fracture morphologies after bending tests, W-W intergranular fracture was the main failure mode for WHAs sintered at 1500 degrees C and 1560 degrees C due to increased W-W contiguity.