Characterization of deformation transition in the rolled LZ91 magnesium alloy under tensile loading

In this study, the mechanical behavior of crystal group of hexagonal close-packed (hcp; α phase) and body-centered cubic (bcc; β phase) during tensile loading was investigated to elucidate the mechanism from elastic to plastic deformation transition of the rolled LZ91 Mg alloy using transmission-X-ray diffraction (transmission-XRD) measurement, transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS). The approximate proof stress of the LZ91 Mg alloy sample was found that the lattice strain retained the expanded state from 0.6% nominal strain, and the transmission-XRD measurement characterized the crystalline behavior during the transition by the integrated intensity of crystal group hcp(100). The lattice strain of bcc(110) decreased from the 0.6% nominal strain due to dislocation activity, which occurred near β/β grain boundary. In addition, we performed the analyses of electron energy loss spectroscopy (EELS) modes, the Li-K peak disappeared from the segregated Li regions of 10–60 nm near β/β grain boundary at the nominal strain of 0.8%. Understanding this mechanical behavior during the elastic to plastic deformation transition by transmission-XRD is crucial for the development of Mg-Li alloys.