Influence of purity level on the structural evolution and the mechanical properties of the Ti-48Al alloys

The influence of the alloy purity level on the properties of Ti-48Al was studied using two sets of samples. The main difference in composition between them was the oxygen concentration, 15 and 980 wt ppm, respectively. The characteristic mechanical values at room temperature, Vickers microhardness, proofstress in compression and creep behaviour at 1073 K were studied for the two sets and for two different microstructures, lamellar microstructure (fully transformed) and duplex microstructure. For the purity levels under study, the oxygen concentration did not influence the microstructure or the room temperature mechanical properties. The creep tests at 1073 K showed that the steady-state strain rate of the pure lamellar alloy was an order of magnitude larger than that of the impure lamellar alloy. In the case of the duplex microstructure, the impurity effect was much less important. The creep strength of the impure lamellar alloy was greater than that of the duplex alloy.