Effect of Cu on nanocrystallization and plastic properties of FeSiBPCu bulk metallic glasses

This study was focused on improving the plastic properties of FeSiBP bulk metallic glasses (BMGs) by adding small amount of Cu (0.1–0.6%). BMGs with significant plastic strain of up to around 3.1% and a strength of 3.3 GPa were obtained in our investigation. Multiple shear bands and related shear ledges were observed on the deformed specimen. The high plasticity is attributed to the nano-scale inhomogeneity that results from phase separation, which can hinder the propagation of shear bands, in effect promoting multiple shearing. The characteristic size of the α-Fe nanoparticles embedded in the glassy matrix changed with Cu content. Our results indicated a dependence between the plastic behavior and the size of the α-Fe nanoparticles. A higher Cu content resulted in an increase in the size of the α-Fe nanoparticles. Of all the samples tested in our investigation, the (Fe0.76Si0.096B0.084P0.06)99.9Cu0.1 alloy exhibited the best plastic properties.