Research On W-Ni-Fe-Co Alloys Fabricated By Selective Electron Beam Melting From Pre-Alloyed Powder

W-Ni-Fe-Co pre-alloyed powder was prepared by plasma rotating electrode process, and then selective electron beam melting (SEBM) was performed. Results show that W-Ni-Fe-Co pre-alloy powder consists of spherical powders and irregular powders with the microstructure of tungsten particles coated by gamma-(Ni-Fe) phase, which contains supersaturated tungsten. Microstructure of the W-Ni-Fe-Co alloy shows certain heredity from powder to SEBMed sample. Since the molten pool is subjected to recoil pressure, hot capillary force and Marangoni convection during SEBM, the instantaneous flow of the molten pool promotes the rearrangement of tungsten particles, leading to a higher uniformity in the SEBM sample than in the powder. Densification process during SEBM is mainly the rearrangement of W particles, and there is no significant dissolution-precipitation process of W. The tensile strength of SEBMed W-Ni-Fe-Co alloy is measured to be 1098 MPa together with a poor ductility. Fracture mode is brittle transgranular fracture of tungsten and ductile tearing of gamma-(Ni-Fe) bonding phase.