A comparative analysis of low temperature deformation in B2 aluminides

Abstract

The microscopic and macroscopic deformation characteristics of three different classes of B2 aluminides have been studied: FeAl, NiAl and RuAl. Strain rate change experiments over the temperature range of −196 to 600°C reveal a high temperature sensitivity of the flow stress, high rate sensitivity and low activation areas for deformation in NiAl, in contrast to FeAl and RuAl. NiAl, like many other higher temperature B2 compounds, deforms by glide of 〈100〉 dislocations. The 〈100〉 dislocations are subject to frequent cross slip that constrains deformation and results in the formation of a high density of jogs and dipoles. Fe–40Al–0.2Zr, similar to other lower temperature B2 compounds, deforms by glide of relatively mobile 〈111〉 dislocations. RuAl displays unusual deformation characteristics for a compound with a high melting point of 2060°C. Following deformation, approximately equal densities of 〈100〉 and 〈110〉 dislocations are present on {110} planes over the range of temperatue investigated. The implications of these observations with respect to the ‘intrinsic deformability’ of B2 aluminides is discussed.