Microstructural evolution, mechanical properties and corrosion resistance of Ti-12Ni alloy fabricated by laser powder bed fusion

The microstructural evolution, mechanical properties, and corrosion behavior of Ti-12Ni (wt.%) specimens produced by laser powder bed fusion (LPBF) using various volume energy density (VED) processing parameter values were investigated. The results showed that the alloy prepared at a low VED of 67 J/mm 3 consisted of near-β grains. At a VED of 133 J/mm 3 the alloy exhibited coarse primary Ti 2 Ni and fine eutectoid structure. This eutectoid structure consisted of α laths and two types of nanoscale Ti 2 Ni, one in the form of short rods and the other with a spherical morphology. Further increase of the VED to 267 J/mm 3 led to coarsening of the eutectoid structure. The dispersed Ti 2 Ni nanoparticles exhibited a significant strengthening effect. The alloy produced at a VED of 133 J/mm 3 showed the greatest strength with a nanohardness of (7.8±0.1) GPa and a compressive strength of (1777±27) MPa. However, the presence of Ni segregation and holes produced by the LPBF processing adversely affected the corrosion resistance of the alloy.