Laser metal deposition of TiB/Ti6Al4V composites with first-scale network microstructure

Abstract

This study investigated the effect of in-situ alloying of Ti6Al4V and TiB2 during laser metal deposition for microstructure, hardness and tensile properties enhancement. It was found that the addition of TiB2 at powder feed rates of range 0.1–0.3 rpm resulted in the formation of TiB whiskers with columnar and equiaxed network morphologies, in a lamella α + β matrix. By increasing TiB2 at 0.4–0.5 rpm, a complete dissolution of the equiaxed and columnar network morphologies were achieved. The dissolution led to a random distribution of formed TiB whiskers, resulting in enhanced hardness and ultimate tensile strength (UTS), with the 0.5 rpm giving the highest hardness and UTS values of 511 ± 13 HV and 1745 MPa, respectively.