Abstract
Mg-xGd-1Zn-0.4Zr (x = 3, 6, and 9 wt.%, denoted as GZ31K, GZ61K, and GZ91K) ingots underwent solid solution treatment (T4), solid solution and aging treatments (T6). Microstructures and mechanical properties of the alloys were studied. The results showed that with the increase of Gd content, the β-(Mg, Zn)3Gd-phase at grain boundaries increased for the as-cast alloys. After T4 treatment, the β-phase was almost dissolved into the matrix, and the needle-like precipitated phase was observed. Block precipitates were formed in the GZ61K and GZ91K alloys after T6 treatment. The microhardness and yield strength of the as-cast alloys increased with the increase of Gd as well as with T4 and T6 treatments. Among them, GZ91K-T6 exhibits the best comprehensive mechanical properties, which is the highest hardness (75.9 HV), tensile yield strength (133 MPa), ultimate tensile strength (261 MPa), and moderate elongation (15.9 %).

Key words
magnesium alloy, heat treatment, microstructure, mechanical properties

Full text (2243 KB)