Diffusion behavior of Ta and Re in tungsten alloy with different addition methods

Abstract

The addition of Ta or Re alone can improve the performance of tungsten alloys, but the combined addition of Ta and Re results in complex diffusion behavior and the formation of new phases. In this work, W-Ta-Re-Ni-Fe alloys with different Re contents were prepared by two methods (direct mixed powder sintering and pre-alloyed powder sintering), the compositions and structures of the precipitated phase through two preparation methods were analyzed, and the diffusion paths of Ta and Re were summarized. The addition of Re contributed to refining the grain size of tungsten alloys, but excessive Re addition led to the formation of hexagonal and tetragonal solid solution mesophases. Mechanical alloying not only strengthened the W particles substantially but also inhibited the growth of mesophases. In-situ Ni3Ta coherent nano-reinforced phase was generated by the diffusion reaction of Ta and Ni, which substantially increased the strength of the matrix phase. These findings suggest that the composite addition of Ta and Re is expected to further improve the toughness of tungsten alloys by adjusting the addition amounts of Ta and Re and improving the powder pretreatment.