| Abstract: | Although using elemental powder mixtures may provide broad alloy selection at low cost for selective laser melting(SLM),there is still a concern on the resultant microstructural and chemical homogeneity of the produced parts.Hence,this work investigates the microstructure and mechanical properties of a SLM-produced Ti-35Nb composite(in wt％)using elemental powder.The microstructural characteris-tics including β phase,undissolved Nb particles and chemical homogeneity were detailed investigated.Nanoindentation revealed the presence of relatively soft undissolved Nb particles and weak interface bonding around Nb-rich regions in as-SLMed samples.Solid-solution treatment can not only improve chemical homogeneity but also enhance bonding through grain boundary strengthening,resulting in～43％ increase in tensile elongation for the heat-treated Ti-35Nb compared to the as-SLMed counter-part.The analyses of tensile fractures and shear bands further confirmed the correlation between the different phases and the ductility of Ti-35Nb.In particular,the weak bonding between undissolved Nb and the matrix in the as-SLMed sample reduces its ductility while the β grains in solid-solution treated Ti-Nb alloy can induce a relatively stable plastic flow therefore better ductility.This work sheds insight into the understanding of homogenization of microstructure and phases of SLM-produced alloys from an elemental powder mixture. |
