Glass Forming and Thermal Properties of the Mg_(65)Cu_(25)Gd_(10-x)Nd_x(x=0 ～ 10) Amorphous Alloys

摘要

The Mg_(65)Cu_(25)Gd_(10-x)Nd_x(x=0 ～ 10) amorphous alloy rods with 3～6 mm in diameter were prepared by Cu-mold injection method. The thermal properties and mechanical properties of these amorphous alloys have been investigated by DSC, SEM with EDS capability, X-ray diffractometry (XRD) and Vickers hardness test. The XRD revealed that these entire as-quenched Mg_(65)Cu_(25)Gd_(10-x)Nd_x alloy rods exhibit a broaden diffraction pattern of amorphous phase. A clear T_g (glass transition temperature) and supercooled region (about 30～60 K) were revealed for all of those Mg_(65)Cu_(25)Gd_(10-x)Nd_x alloys. In addition, the single stage crystallization of the Mg_(65)Cu_(25)Gd_(10) alloy was found to change into two stages crystallization when the Nd element was added into this alloy. In parallel, the crystallization temperature (T_x) and supercooled region (ΔT_x) presents a decreasing trend with increasing Nd content. The lowest liquidus temperature (T_1, about 721 K) occurs at the Mg_(65)Cu_(25)Gd_8Nd_2 alloy. In addition, The Mg_(65)Cu_(25)Gd_8Nd_2 alloy exhibits the high y value (0.416, defined as γ= T_x/T_g+T_l), a relatively high T_(rg) (0.59, defined as T_(rg) = T_g/T_l) and the highest hardness in these alloys.