Effect of Nb addition on mechanical properties and corrosion behavior of Ti6AI4V alloy produced by selective laser melting

摘要

In this research, a novel titanium metallic composite, Ti6AI4V powder mixed with 5 at.% Nb powder, was fabricated by selective laser melting (SLM). The effect of Nb addition on their phase transformation, microstructure evolution, mechanical properties, and corrosion behavior were studied. Interestingly, the novel alloy shows a combination of superior plastic deformation (ε_p = 18.9 ± 1.8%) and high compressive strength (σ_c = 1593 ± 38 MPa), which is 60.2 and 3.2% higher than that of the SLM-processed Ti6AI4V alloy under optimum printing parameters, respectively. However, the yield strength of Ti6AI4V + 5Nb (973 ± 45 MPa) is lower than that of the Ti6AI4V alloy (1066 ±12 MPa). The solidification mechanism changes from planar to cellular mode with Nb addition. The ultrafine microstructure β grains are observed, which show a columnar shape and cellular shape. More importantly, the volume fraction of the β phase is significantly increased from 3.7% to 20.4% because of the Nb addition. In addition, the Ti6AI4V + 5Nb alloy possesses better corrosion resistance than the Ti6AI4V alloy. The research highlights that the addition of Nb powder in Ti6AI4V processed by SLM can improve the mechanical properties and corrosion resistance of the material.