Amorphous to icosahedral phase transformation in rapidly quenched Al–Cu–V and Al–Cu–Ti alloys

Abstract

A comparative investigation of stabilization of amorphous phase and its transformation behaviour in Al75Cu15V10, Al65Cu25V5Ti5 and Al50Cu45Ti5 alloys has been carried out employing X-ray diffraction (XRD) and transmission electron microscopy (TEM) and supported by differential scanning calorimetry (DSC). The DSC curve corresponding to amorphous alloy Al75Cu15V10 shows two stages of crystallization with peak positions at 306 °C and 420 °C. XRD and TEM investigations reveal that the first stage of crystallization corresponds to nanosized crystal formation of Al2Cu phase, which is dispersed in the amorphous matrix. The second stage of crystallization corresponds to growth of icosahedral phase. Partial substitution of Ti in place of V in Al65Cu25V5Ti5 alloy stabilizes amorphous phase, which after subsequent annealing at 400 °C for 2 h transforms to a crystalline phase. Amongst several compositions in the Al–Cu–(Ti,V) alloy system prepared during present investigation, amorphous-to-icosahedral phase transformation has only been observed in Al50Cu45Ti5 alloy after isothermal annealing at 300 °C for 2 h. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)