Selective laser melting of low modulus Ti-Mo alloy: α/β heterogeneous conchoidal structure

• Published in: Materials letters 2020-05, Vol.267, p.127544, Article 127544
• Main Authors: Kang, Nan, Lin, Xin, Coddet, Christian, Wen, Xiaoli, Huang, Weidong
• Format: Article
• Language: English
• Subjects: Chemical composition; Heterogeneous microstructure; Laser beam melting; Materials science; Materials selection; Mechanical properties; Melt temperature; Metallurgy; Metals and alloys; Modulus of elasticity; Molybdenum; Powder mixture; Rapid prototyping; Selective laser melting; Tensile strength; Ti-Mo alloys; Titanium base alloys
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2020.127544

•A novel low modulus, high strength Ti-7.5Mo was prepared by SLM from mixed powder.•An heterogeneous conchoidal structure consists by α and β phase appears.•The α/β synergism effect offers low modulus, high strength and ductility. The powder mixture, which used as feedstock materials in selective laser melting (SLM), always brings the undesirable problem in microstructure and then mechanical properties, due to its inhomogeneous chemical composition and stability. In this work, the in-situ SLMed Ti-7.5Mo alloy presents an heterogeneous conchoidal structure (hcp α-Ti and bcc β-Ti) from elemental powder mixture. During the SLM, the Mo, which possesses high melting temperature and density, was partial melted and then driven by Marangoni flow in molten pool. Thus, elemental micro-segregation appears with a result of special conchoidal structure. The SLMed sample shows low Young’s modulus (70 GPa) with high tensile strength (>700 MPa) and ductility (9%), given to the synergism effect of β channel and α island.