Effects of noble metal additons on plastic deformation of Zr-Cu-Ni-Al based bulk metallic glasses

Zr-Cu-Ni-Al bulk metallic glasses (BMGs) have been limited in practical applications because of their low ductility under tensile and compressive testing conditions. This may be due to the formation of highly localized shear bands during plastic deformation. In this study, effects of Pd, Pt, Au and Ag additions on mechanical properties of Zr-Cu-Ni-Al BMGs have been examined. By the noble metal additions, precipitation of the icosahedral quasicrystal phase (I-phase) in the supercooled liquids was observed. Compression tests were carried out in these BMGs at an initial strain rate of 1 × 10-4 s-1 at room temperature. Especially, in the case of the Au-addition, large plastic deformation was observed and many shear bands were also observed in wide region of the side-surface of the fractured specimens. This may be due to dynamic precipitations of nanocrystalline particles inside the shear bands during compressive deformation that prevent the propagations of the deformation shear bands.