Compressive deformation of MoAlB up to 1100 °C

Quasi-static and cyclic compression tests at room and high temperatures were conducted on MoAlB, which has an atomically laminated structure that consists of a Mo-B sublattice interleaved by double layers of pure Al. The results show that MoAlB goes through a brittle-to-plastic transition (BPT) at around 800 °C. Below the BPT temperature, MoAlB behaves as a linear-elastic solid and fails in a brittle manner at stresses exceeding 2 GPa despite the fact that the grain size was 6 ± 1 μm. While post-testing microstructural observation showed only a few bends and kinks of individual grains, extensive microcracking was observed. Above the BPT temperature, the deformation was non-linear elastic with open stress-strain hysteresis loops and small irrecoverable strains after each loading-unloading cycle. This behavior was attributed predominantly to micocracks that appear to be constrained mostly within a shear band and coalesce into larger cracks.