Role of minor addition of metallic alloying elements in formation and properties of Cu-Ti-rich bulk metallic glasses

The effect of minor addition (MA) of metallic alloying elements in Cu-Ti-rich Cu-Ti-Zr-Ni-Si bulk metallic glasses (BMGs) has been investigated. MA of elements having a relatively small positive enthalpy of mixing (partial substitution of Zr with Nb) leads to enhancement of compressive plasticity (up to about 5% of fracture strain) when the addition leads to improvement in glass-forming ability (GFA). If the GFA is reduced (partial substitution of Ni with Ag or Co), the plasticity is also reduced. On the one hand, the MA of elements having a relatively large positive enthalpy of mixing (partial substitution of Zr with Y) can lead to the liquid-state phase separation in Cu-Ti-Zr-Ni-Si(-Sn) BMGs, although the addition can lead to drastic deterioration in GFA and plasticity. This concept would be considered to be effective even in design of other BMG systems with tailored properties.