glass formation in cu50zr50-xalx and (cu50zr43al7)100-xnbx alloys

In the present work, the effects of al and nb elements on the formation of glassy phase in cu-zr based bulk metallic glasses (bmgs) have been investigated. in this regards, different cu50zr50-xalx and (cu50zr43al7)100-xnbx samples with 2 mm in diameter were prepared using arc melting followed by injection casting in water-cooled copper mold. the results illustrated that al has positive effect on increasing the glass forming ability (gfa) of cu-zr system, and it is possible to create a completely glassy structure in cu50zr43al7 sample. in contrast, the addition of nb has destructive effects on glass forming ability, the homogeneity and final mechanical properties of cu-zr-al bmgs. the segregation of nb during solidification process and precipitation of brittle b2-cuzr and cu10zr7 phases are the main reasons of lower ductility and compressive strength in the presence of nb element. as-solidified samples containing nb showed compressive fracture strength in the range of 1000-1650 mpa, which was much lower than nb-free alloy (2050 mpa).