Effects of Zn on the glass forming ability and mechanical properties of MgLi-based bulk metallic glasses

Abstract

Through the addition of Zn element, Mg-Li-Cu-Zn-(Y, Gd) bulk metallic glasses (BMGs) with diameter of 2mm have been successfully fabricated by conventional copper mold injection casting method. The X-ray diffractometer (XRD) patterns and differential scanning calorimeter (DSC) traces demonstrated that the as-cast Mg60Li5Cu20Zn5(Y, Gd)10 BMGs were fully amorphous phase. By the minor addition of 5at.% Zn, the supercooled liquid regions (SLR) of Mg60Li5Cu20Zn5(Y, Gd)10 BMGs increased 6K and 3K respectively compared with that of Zn-free samples, which implied that their glass forming ability (GFA) and thermal stability were improved. It was also proved that the addition of Zn effectively enhanced the alloys’ fracture strength (453MPa and 456MPa) and elastic strain (0.75% and 0.92%), which were much higher than that of Mg60Li5Cu25Y10 BMG (403MPa, 0.62%) and Mg60Li5Cu25Gd10 BMG (412MPa, 0.82%).