Influence of Tungsten Addition on Microstructure and Tensile Properties of Ti6Al4V Fabricated by Laser-Directed Energy Deposition

Abstract

The addition of tungsten can improve the high-temperature oxidation resistance of titanium alloys. However, as its applications continue to expand, new demands are being placed on its room temperature strength. Here, we provide a dense titanium alloy with high strength by introducing proper W powders into the Ti6Al4V powders under direct energy deposition. The effect of tungsten addition on the microstructure and tensile properties of the Ti6Al4V alloy was investigated. Compared to pure Ti6Al4V, the titanium alloy with tungsten addition exhibited refined α′ martensite and β grains, which is attributable to the effect of tungsten on the structural subcooling of titanium and on the formation temperature of the α′ martensite. Owing to the synergistic strengthening effects of grain refinement and solid solution strengthening, the W-containing alloy shows a high tensile strength of 1333 MPa and yield strength of 1219 MPa, which are significantly higher than Ti6Al4V alloy’s tensile strength of 940 MPa and yield strength of 860 MPa. This approach provides a pathway for design and preparation of high-strength titanium alloys by additive manufacturing.