Fabrication of a thick surface layer of Al3Ti on Ti substrate by reactive-pulsed electric current sintering

The thick intermetallic compound Al3Ti layer was formed by reactive-pulsed electric current sintering (PECS) of mechanically alloyed powders set on the Ti substrate to improve the wear and oxidation properties. During heating by PECS, Al and Ti in MA powders reacted to form an Al3Ti layer, and simultaneously reacted with the Ti substrate to achieve joining between the surface layer and substrate. The densification behavior of the synthesized surface layer, and the reaction kinetics between the surface layer and substrate were investigated. By holding at 1100 K for 180 s under 40 MPa, a fully dense and homogeneous Al3Ti surface layer with a thickness of about 1600 μm was obtained. However, a higher temperature (1210 K) or longer holding time (over 1800 s) was required to eliminate voids on the Al3Ti/Ti interface. The obtained Al3Ti layer exhibited almost the same properties as cast bulk Al3Ti for hardness, wear and oxidation.