Formation of TiAl 3 layer on titanium alloys

Abstract

Substrates of titanium alloys OT4-1 and VT3-1 were ion plated with aluminium and subsequently annealed in an argon atmosphere at temperatures from 803 to 908 K for 1–20 h and in air at a temperature of 1173 K for 20, 40, 60 and 80 h. At lower annealing temperatures a TiAl 3 layer with a tetragonal lattice ( a = 0.3849 nm, c = 0.4305 nm) was identified and its Vickers microhardness was found to be in the range H v0.01 = 1100–1200 kgf mm −2. At an annealing temperature of 1173 K interlayers of Ti 3Al, TiAl 2 and TiAl are formed within the TiAl 3. The measured values of the microhardness were in the range H v0.01 = 500–600 kgf mm −2. The growth of the TiAl 3 layer is governed by the parabolic diffusion law.