Effects of refractory Nb on glass-forming ability and structure inhomogeneity of Cu50Zr50 binary metallic glass

Abstract

This paper reports the effects of refractory Nb metal on the structural heterogeneity of a CuZr metallic glass. Cu50Zr50 metallic glass was taken as model material, and different quantities of Nb element (5 at% and 10 at%) was considered to comparatively study heterogeneity. The as-spun metallic glassy ribbons were examined with x-ray diffraction, differential scanning calorimetry and dynamic mechanical analysis. The results indicate that Nb element can decrease the glass-forming ability but enhance the glass transition temperature and thermal stability. For heterogeneity, the addition of 5 at% of Nb element will weaken the heterogeneity and the addition of 10 at% of Nb element will improve the heterogeneity. This work also disclosed that the time window from the onset temperature to the peak temperature of β relaxation for (Cu0.5Zr0.5)90Nb10 is larger than that for (Cu0.5Zr0.5)95Nb5, suggesting that Nb element may suppress the local motion from a smaller region to a larger region in the metallic glass.