Synergistic enhancement of strength, ductility and corrosion resistance of Ti6Al4V alloy through low Cu doping and hot extrusion

Abstract

Cu-containing Ti6Al4V alloy is considered an ideal biomedical material due to its excellent antibacterial properties. However, the addition of Cu leads to a mismatch in strength, ductility, and corrosion resistance, which hinders their further application. To address this issue, the study utilized low Cu doping and hot extrusion to optimize the material's properties. The results showed that the primary lamellar structures were transformed into equiaxed grains, with an average grain size reduced from 10 μm to 300 nm. The nano-equiaxed grains had a homogeneous elemental composition and a stronger base texture, with orientations aligned with the extrusion direction. As a result, synergistic strengthening in terms of strength, ductility, and corrosion resistance was achieved. The film resistance increased from 127 kΩ·cm2 to 325 kΩ·cm2, the ultimate tensile strength (UTS) increased from 1030 MPa to 1330 MPa, and the elongation increased from 7% to 21%. These improvements were attributed to the nanostructure and basal texture, which facilitated the formation of a thicker passive film and reduced pitting corrosion, thereby enhancing corrosion resistance. Additionally, the nano-equiaxed grains could provide grain boundary strengthening and texture strengthening on UTS and ensure uniform deformation for elongation.