Devitrification of nano-scale icosahedral phase in multicomponent alloys

A nano-scale icosahedral phase forms as first crystallization product upon devitrification of multicomponent amorphous (Ti 33Zr 33Hf 33) 50(Ni 50Cu 50) 40Al 10, (Ti 33Zr 33Hf 33) 60(Ni 50Cu 50) 30Al 10 and (Ti 33Zr 33Hf 33) 65(Ni 50Cu 50) 27.5Al 7.5 alloys (numbers indicate at.%). The onset temperatures and the values of the activation energy for the devitrification of the nano-scale icosahedral phase decrease with increasing (Ti 33Zr 33Hf 33) content in these alloys. This indicates that the structural similarity between the amorphous and the icosahedral phases increases with increasing (Ti 33Zr 33Hf 33) content. Furthermore, the devitrified nano-scale icosahedral quasicrystals form in a wide compositional range regardless of the (Ti 33Zr 33Hf 33) content suggesting that the icosahedral phase in these novel multicomponent alloys, developed by equiatomic substitution may have an extensive solid solubility. After further heat treatment the devitrified nano-scale icosahedral phase fully decomposes into MgZn 2-type crystals reflecting its metastability.