The tracer diffusion coefficients of 51Cr and 54Mn in a γ-TiAl intermetallic compound containing 54.1at%Al were determined at 1095 to 1470K. The temperature dependence of both diffusing species obeyed a linear Arrhenius behaviour and could be described by:

Cr:     D(m2 /s)  =  4.4  x  10−3exp[-350( kJ/ mol)/RT]

Mn:     D(m2 /s) = 1.2  x  10−3 exp[-326( kJ/mol)/RT] 

The data were analysed on the basis of empirical correlations between the diffusion and melting parameters applicable for conventional mono-vacancy diffusion mechanism in metals. It was concluded that impurity diffusion in γ-TiAl occurred through the migration of thermal vacancies via nearest-neighbour or next-nearest neighbour jumps.

Diffusion of Chromium and Manganese in γ-TiAl. G.P.Tiwari, Y.Iijima, C.G.Lee, B.H.Koo: Philosophical Magazine, 2011, 91[5], 751-71