Enhanced glass forming ability and plasticity of Mg-based bulk metallic glass by minor addition of Cd

•The GFA, thermal stability and mechanical properties are enhanced by Cd addition.•The dimples and vein patterns are found in fracture surface of Cd-additive alloy.•The Cd addition could increase the structural stability to enhance the strength.•The interatomic force among Cd and other atoms may account for phase separation.

The effect of the Cd addition on the glass forming ability and mechanical properties was studied in (Mg61Cu28Gd11)100−xCdx (x = 0, 0.5, 1.0, 2.0, 3.0, and 5.0 at.%) alloys. With increase of Cd addition, glass transition temperature Tg and onset temperature of crystallization Tx both increase gradually from 419 K and 480 K for Mg61Cu28Gd11 to 426 K and 496 K for (Mg61Cu28Gd11)97Cd2 but then decrease, resulting in the maximum supercooled liquid region ΔTx obtained by glassy alloy with 2.0 at.% Cd. The slightly increase of γ-value and the reduced glass transformation temperature Trg with the increase of Cd content consistent with the experimental results of glass forming ability. By increasing the Cd content to 2.0 at.%, the compressive strength and plastic strain of Mg–Cu–Gd–Cd glassy alloy reaches about 904 MPa and 0.45%, respectively. The fracture morphology is changed from netlike striation to homogeneous dimples and local vein pattern, indicating that the minor addition of Cd clearly improves the plasticity of Mg-based glassy alloys. It is suggested that the Cd addition could enhance the strength and plasticity of Mg-based glassy alloys by increasing the structural stability during deformation and stimulating the chemical inhomogeneity and fluctuation in local free volume distribution to block the free propagation of shear bands.