Selective laser melting of low modulus Ti-Mo alloy: alpha/beta heterogeneous conchoidal structure

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 alpha-Ti and bcc beta-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 beta channel and alpha island. (C) 2020 Elsevier B.V. All rights reserved.