On the solid solution substitutional position and properties of Mg–Gd alloy

Abstract

The effects of gadolinium addition on crystallographic characteristics (lattice parameters, c/a ratios, solid solution substitutional position) and physical properties (electrical conductivity, Vickers hardness and mechanical performance) of Mg–Gd alloy were investigated in the present work. The results show that the Gd atoms in Mg–Gd binary alloy prefer to be located on the prismatic plane. The solid solution strengthening and ductilizing effect of Mg–Gd alloy mainly occurs in the composition range of 1–4 wt.% Gd. With the increase of Gd content, the axial ratio c/a of the extruded alloy first decreases and then increases, which is consistent with the change law of the alloy ductility. With the increase of Gd content in the low addition range, the starting resistance of basal slip increases sharply, while that of prismatic slip increases slowly. The difference between these two kinds of resistance gradually approaches to a certain extent with the increase of Gd content, which is beneficial to the coordination of basal slip and prismatic slip, and plays a plasticizing role. However, when the Gd content exceeds a certain amount, the volume fraction of the second phase in the alloy is too high, which is unfavourable to the elasticity. Under the high addition of Gd, when the starting resistance of prismatic slip and basal slip tend to be close and the difference is relatively constant, the hardening exponent also decreases to a relatively low stable value.