X-ray diffraction study on the microstructure of a Mg–Zn–Y alloy consolidated by high-pressure torsion

Mg95Zn4.3Y0.7 (at.%) alloy powder produced by an inert gas-atomizer was consolidated by high-pressure torsion (HPT) at room temperature and 373 K. The phase composition and the microstructure were investigated by X-ray diffraction and the microstructural parameters were correlated to the yield strength. HPT-processing yielded an ultrafine-grained microstructure with high dislocation density, leading to a large yield strength of the samples. Both the gas-atomized powder and the consolidated samples contained an icosahedral Mg3YZn6 phase (I-phase) besides the main phase of α-Mg. It turned out that the I-phase dispersoids strengthen the consolidated material indirectly by increasing the dislocation density due to their pinning effect.

► Mg95Zn4.3Y0.7 powder was consolidated by HPT at RT and 373 K. ► The consolidated disks comprised ultrafine grains with high density of dislocations. ► Quasicrystalline dispersoids strengthen the material by increasing the dislocation density. ► Twinning in the Mg matrix was marginal during HPT.