Improving plasticity and toughness of Cu-Zr-Y-Al bulk metallic glasses via compositional tuning towards the CuZr

Abstract

In this work, we propose a simple approach for designing plastic bulk metallic glasses (BMGs) by exploiting the ductility of intermetallic compounds involved in the BMG-forming system. Its validity was examined by investigating a series of quaternary Cu-Zr-Y-Al alloys along the composition tie-line between Cu42Zr44.4Y3.6Al10 (Y1) and the B2 CuZr phase, expressed as (Cu0.5Zr0.5)x(M)100-x (M = Zr0.15Y0.225Al0.625, 84≤x≤93). When tuning the composition towards the CuZr, the glass-forming ability of alloys is dramatically degraded, showing a reduction of critical diameter Dc for BMG formation from 16 mm at x = 84 (Y1) to 2 mm at x = 93. As the composition of BMGs shifts to the CuZr terminal, the shear modulus μ of the BMGs decreases, whereas the Poisson's ratio ν increases. With respect to the Y1 BMG, compressive plasticity and toughness of the Y2 BMG (x = 92, Dc = 4 mm) with a higher concentration of the CuZr are improved, which is consistent with its lower μ and higher ν values.