In Situ Alloyed Refractory High Entropy Alloy by Laser Powder Bed Fusion

Pre-alloyed powders, which are mainly used in laser powder bed fusion (LPBF), have the disadvantage of being time-consuming and costly to manufacture. To overcome these disadvantages, in-situ alloying, which mixes pure element powders and performs alloying in real time during the LPBF process, has been attracting attention. In particular, it is quite challenging to manufacture high entropy alloy (HEA) containing high melting point refractory elements by in-situ alloying. In this study, we designed a single-phase BCC refractory HEA with a mix of Ti, Nb, Mo, Ta, and W through thermodynamic calculations and fabricated the designed composition by LPBF by mixing powders of each element and performing in-situ alloying. High energy density and remelting effectively suppressed segregation of constituent elements, which caused a decrease in residual stress and increased relative density. Our study represents a pioneering attempt to manufacture in-situ alloyed HEA by LPBF and demonstrates the effectiveness of in-situ alloying using mixed powders.