Structural relaxation, glass-forming ability and mechanical properties of Mg-Cu-Ni-Gd alloys

The structural relaxation and glass-forming ability (GFA) of Mg-Cu-Gd-based glassy alloys and the effect of Ni addition on the glass-forming ability, structural relaxation and mechanical properties were studied by thermal analysis, X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The medium-range order (MRO) zones of about 1-2 nm size were observed in the Mg65Cu25Gd10 glassy alloy after structural relaxation caused by annealing for 180 s at 305 K. The structural relaxation resistance increased with decreasing Cu content, although the GFA also decreased in Mg-Cu-Gd-based alloys. Appropriate substitution of Cu by Ni in Mg75Cu15Gd10-based alloy not only improved the glass-forming ability and mechanical properties, but also increased the stability against structural relaxation.