Roles of minor rare-earth elements addition in formation and properties of Cu-Zr-Al bulk metallic glasses

The effect of RE addition on glass-forming ability (GFA) and mechanical properties of (Cu47Zr45Al8)100−xREx (RE = Ce, Nd, Gd, Y, Dy, Lu, x = 0-4 at.%) bulk metallic glasses (BMGs) has been studied in this paper. It has been found that trace amount of rare-earth addition in the Cu-rich Cu-Zr-Al alloys can decrease the temperature of glass transition (Tg) and increase γ(γ = Tx/(Tg + Tl)) value, and therefore improve the GFA. The (Cu47Zr45Al8)96Y4 bulk metallic glass with critical diameter of 25 mm was prepared by copper-mold-casting. The (Cu47Zr45Al8)97Lu3 bulk metallic glass exhibited good plasticity 4.65% at room temperature during compression test, which was applied high yield strength of 1840 MPa. With the increase of rare-earth elements addition up to 4 at.%, the fracture strength of the alloy reduced obviously and no more plastic deformation can be observed on the fracture surface. Young's modulus, fracture strength and Poisson's ratio were investigated for the mechanism of deformation (from plasticity to brittleness) in the compression tests.