The densities of thermal vacancies and residual dislocations in bulk specimens of Fe–40at%Al were investigated using differential dilatometry and X-ray diffraction. A large quenched-in vacancy concentration at above about 873K was apparent from the decrease in average lattice parameter. This was correlated to a lowering of the effective enthalpy of vacancy formation from about 91 to 42kJ/mol, possibly caused by the presence of different types of point defect in lower- and higher- temperature regimes. The residual dislocations were found to have a major concentration on {100} planes at any given temperature. An increase in the dislocation density and a concurrent fall in the vacancy concentration was observed with a lowering of the quenching temperature from 1223 to 1073K, indicating the possibility of vacancy annihilation at 1073K.

A Study of Thermal Vacancies and Dislocation Structure in Fe–40at.%Al. J.Joardar, R.Y.Fillit, A.Fraczkiewicz: Philosophical Magazine Letters, 2005, 85[6], 299-309