Dislocations-induced precipitates and their effect on mechanical properties of Mg-Gd-Y-Zr alloy

Optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and tensile machine were used to characterize the microstructures and mechanical properties of as-forged and aged Mg-9.5Gd-3.8Y-0.6Zr alloys. The results show that a novel kind of dislocation arrays, comprising parallel arranged dislocations, were obtained in the forged alloy. The arrays tend to extend parallel and are heterogeneously distributed with adjacent distances varying from 0.3 µm to 1.4 µm. After aging the alloy at 265 °C, a large number of preferential-oriented β' phases were precipitated on the dislocation arrays, forming a structure of “precipitation chains” (PCs), which results in simultaneous increments of strength and ductility.