Comparing the origin of ductility in the Zr–Al–Ni–Cu–M (M = Nb, Pd) metallic glasses

The origin of Zr65Al7.5Ni10Cu12.5Pd5 and Zr65Al7.5Ni10Cu12.5Nb5 glassy alloys exhibiting a remarkable plastic strain of about 6% and over 10%, respectively, under compressive deformation is compared. Observation by transmission electron microscopic (TEM) indicates that the deformation-induced structural transformation from monolithic glassy phase is responsible for the large plasticity. The degree of structural change, however, is different between both alloys: the fcc-Zr2Ni crystals emerged within glassy phase for the former, while only ordered clusters were observed for the latter. The difference is suggested to correlate to the slower grain-growth of the primary crystallization phase in the Zr65Al7.5Ni10Cu12.5Nb5 compared to those in the Zr65Al7.5Ni10Cu12.5Pd5 alloy.