On the work hardening behavior of machining WNbMoTaZrx (x = 0.5 and 1.0) refractory high entropy alloys

Abstract

Tool wear and surface quality are significantly influenced by work hardening during machining. This work focused on the work hardening behavior during the machining of WNbMoTaZr_x (x = 0.5 and 1.0) refractory high entropy alloys (RHEAs). The effect of polycrystalline cubic boron nitride tool geometric parameters on cutting forces, Vickers hardness, and the microstructure of machined side surface of RHEAs was studied. It was found that the RHEAs showed different degrees of work hardening. Compared to WNbMoTaZr_0.5, the softer and tougher interdendrites of WNbMoTaZr_1.0 compressed the dendrite area under the grinding and squeezing effect of negative chamfering surface, which effectively reduced the degree of work hardening and led to the appearance of abnormal cutting forces. The changes of negative chamfer angles and tool corner radius also affected the degree and behavior of work hardening. In conclusion, RHEAs showed different work hardening behaviors, including dendrite refinement, dendrite breakage, and dendrite compression, which in turn resulted in different degrees of work hardening and increase in cutting force.