Deformation and Fracture of L12 Trialuminides

Abstract

We review here recent experimental and theoretical work aimed at characterizing and understanding the deformation and fracture behavior of L12 trialuminides, with emphasis mainly on AI3Ti-base alloys. We also review recent work on the binary compound AI3Sc, which is a model L12 trialuminide that is being studied for comparison with first-principles quantum mechanical calculations. The topics covered in this review include: alloy-element effects and phase stability; dislocation structures; mechanical properties; cleavage fracture behavior; and first-principles calculations of elastic constants, fault energies, and ideal cleavage strengths. We discuss various possible reasons for the brittleness of these alloys, and summarize our current understanding of the rather unusual phenomenon of brittle cleavage in relatively soft materials having the high-symmetry L12 structure. © 1991, The Iron and Steel Institute of Japan. All rights reserved.