Evaluation of contributions of hardening mechanisms to the yield strength of Ti6Al4V-Cu alloys produced by wire electron beam additive manufacturing

The structural-phase state and mechanical characteristics of the Ti6Al4V alloy added with 0.6, 1.6, 6 and 9.7 wt.% of copper, obtained using the double-wire electron beam additive manufacturing (EBAM) have been studied. It was found out that adding copper to the Ti6Al4V alloy resulted in the formation of equiaxed grains and precipitation of Ti2Cu particles that allowed improving both yield strength and tensile strength compared to those of the base EBAM Ti6Al4V. Contributions of three different strengthening mechanisms into yield strength of the Ti6Al4V-Cu alloys have been determined. It has been established that grain boundary strengthening provided main contribution to improving mechanical characteristics of Ti6Al4V-Cu alloys. The contributions of dispersion and solid solution hardening mechanisms to the improvement of the yield strength are comparable and smaller than that of the grain-boundary hardening.