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

The effect of the Cd addition on the glass forming ability and mechanical properties was studied in (Mg61Cu28Gd11)(100-x)Cd-x (x = 0, 0.5, 1.0, 2.0, 3.0, and 5.0 at.%) alloys. With increase of Cd addition, glass transition temperature T-g and onset temperature of crystallization T-x both increase gradually from 419 K and 480 K for Mg61Cu28Gd11 to 426 K and 496 K for (Mg61Cu28Gd11)(97)Cd-2 but then decrease, resulting in the maximum supercooled liquid region Delta T-x obtained by glassy alloy with 2.0 at.% Cd. The slightly increase of gamma-value and the reduced glass transformation temperature T-rg 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. (C) 2013 Elsevier B. V. All rights reserved.