Multiphase polymorphic nanoparticles reinforced titanium matrix composite produced by selective electron beam melting of a prealloyed composite powder

A Ti-6Al-3Sn-4Zr-0.9Mo-0.4Si-0.4Y-0.5B (wt.%) titanium alloy matrix composite (TMC) with multiphase polymorphic TiB whiskers and Y2O3 and (Ti, Zr)(5)Si-3 nanoparticles was successfully fabricated by selective electron beam melting (EBM) of a prealloyed composite powder. The rapid hypoeutectic solidification during EBM results in a columnar dendritic microstructure with three dimensional fine networks of TiB whiskers and Y2O3 nanoparticles uniformly distributed in the interdendritic regions of the parent beta-Ti phase. This EBM-built TMC exhibits a remarkably enhanced tensile strength and hardness compared with its matrix alloy at room temperature and elevated temperatures up to 700 degrees C. The ultimate tensile strength of the EBM-built TMC reaches 1185 MPa with an elongation to fracture of 3.2% at room temperature, and still retains a high value of 750 MPa at 600 degrees C. This study opens up a new way to manufacture high-performance components of TMCs with multiphase polymorphic reinforcements and complex shapes. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.