Effect of additional elements on mechanical properties of a specially constituted Zr-based alloy

Bulk metallic glasses (BMGs), especially ZrCuAlNi alloys, are important materials due to their very attractive physical and mechanical properties. However, their applications are restricted due to processing limitations and cost effectiveness. Materials scientists are trying to design and synthesize economical BMGs using inexpensive materials with improved properties. In the present study, six alloys having compositions (Zr0.65Cu0.18Ni0.09Al0.08)100−xMx (where M = Y, Ti, Nb, Er and W and x = 0 and 2 at.%) were synthesized by Cu mould casting using 2-3N pure elements. The base alloy Zr65Cu18Ni9Al8 was designed following the Inoue's rules and also adopting the criterion of average valance electrons/atom (e/a ratio = 1.3950) and average atomic size Ra = 0.1498 nm. Characterization of alloys was done by XRD, differential scanning calorimetry (DSC) and SEM/EDS. Maximum ΔTx was found to be 129 K for the base alloy. Mechanical properties like Vicker's microhardness, nanohardness, elastic modulus, density, fracture strength and shear angles were measured. Enhancement in ductility was achieved by adding Ti and Nb. Microstructure of as-cast and heat-treated compression tested samples was evaluated.