Interface Stability in Diffusion Couple of L1₀ type TiAl and L1₂ type (Al, Mn)₃Ti Alloys at 1273-1473 K

抄録

Titanium trialuminide coating on L1₀-type titanium aluminide alloys represents a valuable mean to improve oxidation resistance. Selection of L1₂-type titanium trialuminide alloys containing Mn as a coating material is particularly attractive because of its good ductility at room temperature and good oxidation resistance at high temperature of 1273 K . However, stability of the coated titanium trialuminide at high temperature and adhesion to the substrate are not established. Two kinds of diffusion couples composed of L1₀ and L1₂ single phase alloys with or without vanadium were applied to diffusion experiments in a temperature range of 1273–1473 K for 2.5–20 h. During the diffusion process, L1₀ and L1₂ phases coexisted without any inter-phase, irrespective of diffusion temperature and vanadium addition. The diffusion couples composed of the alloys without vanadium exhibited cracked region at the interface between the L1₀ and L1₂ phases, while the diffusion couples composed of the alloys with vanadium exhibited no cracked region. The L1₂-type alloy with vanadium was shown to be an appropriate coating material on the L1₀ alloy.