Formation of glassy and icosahedral phases in as-cast (Zr9Ni4)75(Al1−xTix)25 alloys

The icosahedral atomic cluster has been recognized as the building block of icosahedral quasicrystals (I-phase) and many bulk metallic glasses (BMGs). With this in mind, a series of (Zr9Ni4)75(Al1−xTix)25 alloys were designed, and ribbons and rods of 3 mm in diameter were prepared. Structural analysis of these bulk samples revealed a pronounced alloying effect of Al and Ti on the formation of BMG and I-phase. BMGs were formed at low Ti compositions (x ⩽ 0.20). As the Ti concentration increased, an I-phase began to form in the glassy matrix, and a nearly monolithic I-phase alloy was obtained in the Al-free alloy. The alloying effect is discussed by considering the different roles of Al and Ti in the stabilization of local icosahedral atomic structures.