The mechanical behavior of β-LiAl

Abstract

The plastic deformation of β phase LiAl has been studied through compression tests. Polycrystalline LiAl is brittle at temperatures below 0.7T m where T m is the melting temperature). The ductile-to-brittle transition temperature increases with increasing lithium content. The isotherms of the yield strength showed an increase in strength with increasing lithium content. The compositional dependence of the ductile-to-brittle transition temperature and the yield strength are correlated with the defect structure of β-LiAl. Strain-rate-cycling tests were performed to obtain the activation volumes of plastic deformation of LiAl. The magnitude of the activation volumes is quite small and independent of lithium content. The rate-controlling deformation mechanism may be associated with the nucleation of dislocation kink pairs over a Peierls-Nabarro barrier.