Microstructural homogeneity and mechanical behavior of a selective laser melted Ti-35Nb alloy produced from an elemental powder mixture

• 作者: Jincheng Wang Yujing Liu Chirag Dhirajlal Rabadia Shun-Xing Liang Timothy Barry Sercombe Lai-Chang Zhang
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2021,（2）
• 页码范围: 221-233
• 页数: 13页
• 语种: 英文

摘要

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.