The effect of orientation on the deformation behavior of Cr2AlC

The MAX phases are a group of ternary carbides and nitrides with potential for use in advanced high temperature applications. Numerous studies have shown their main deformation mechanism to be basal plane slip, even in extreme orientations, yet the fundamentals of this mechanism and dependencies on size and applied stress state remain inconclusive. Based on similar studies in Ti3SiC2, Ti3AlC2 and Ti2AlC, the current work investigated the onset of basal plane slip as a function of loading orientation by compressing single crystal micropillars of Cr2AlC. The results suggest clear changes in the critical resolved shear stress with loading orientation (non-Schmid effects), and attempts were made to rationalize this behavior by comparison with models of dislocation activity. On this basis, it is proposed that external influences on dislocation mobility are likely the governing factor in the observed non-Schmid effects in the MAX phases.