Toshisuke Shibata

Formation, thermal stability and mechanical properties of amorphous alloys in the Mg-transition metal(Ni, Cu)-alkaline-earth metal(Ca, Sr, Ba) system

Mg-Ni-Ca, Mg-Ni-Sr, Mg-Ni-Ba and Mg-Cu-Ca alloys were found to be amorphized by melt-spinning in the compositional ranges 0 to 30% Ni and O to 40% Ca, 5 to 20% Ni and 0 to 15% Sr, 10 to 25% Ni and 0 to 15% Ba, and 0 to 50% Cu and 0 to 35% Ca, respectively. In the amorphous Mg-Ni-Ca and Mg-Cu-Ca alloys, the glass transition was observed in the ranges of 7.5 to 15% Ni and 2.5 to 5% Ca and 10 to 40% Cu and 2.5 to 7.5% Ca, respectively. The crystallization temperature (Tx) of amorphous Mg-Cu-Ca alloys increases with increasing Cu content, while Tx for amorphous Mg-Ni-Ca and Mg-Ni-Sr alloys shows a maximum value of 459 and 471 K, respectively, at 15% Ni. The glass transition temperature (Tg) increases monotonously with increasing Ni or Cu content. Amorphous Mg-Ni-Ca and Mg-Ni-Sr ribbons containing more than 80% Mg have a good bending ductility and the highest tensile fracture strength (σf) reaches 690 and 680 MPa, respectively. The ratios of σf to density are nearly equal to those for previously reported Mg-Ni-(Y or Ln) amorphous alloys with higher σf values because of the low densities of the present Mg-based alloys.