Effect of Rhenium and Gadolinium Additions on the Mechanical Properties of Ti-48Al-2Cr-2Nb Sintered Through Spark Plasma Sintering

In this study, rhenium and gadolinium powders are added to pre-alloyed Ti-48Al-2Cr-2Nb powder, with contents varying from 0 to 1 wt.%. The effect of the composition on the relative sintered density, microstructure, phase formation, mechanical properties are studied. Alloy powders are mechanically mixed using planetary mill at 200 rpm for 20 min and fabricated using spark plasma sintering at 1150°C with a heating rate of 100 °C/min at a 50 MPa pressure. Among other alloys, the 75 wt.% Re TiAl alloy had a relative sintered density of 98.13%, Vickers hardness of 312 HV0.5, and the ultimate tensile strength of 744 MPa. On the other hand, the TiAl alloy with a 0.5 wt.% Gd content had the relative sintered density of 98.98%, a duplex microstructure with γ grains and (γ + α₂) lamellar colonies, Vickers hardness of 323 Hv0.5, and ultimate tensile strength of 939 MPa. Thus, TiAl alloys with 0.5 wt.% Gd addition had higher sintered density, hardness, and tensile strength than all other studied alloys with rhenium and gadolinium addition..