Devitrification of rapidly quenched Al-Cu-Ti amorphous alloys

Abstract

X-ray diffraction, transmission electron microscopy and differential scanning calorimetry were carried out to study the transformation from amorphous to icosahedral/crystalline phases in the rapidly quenched Al50Cu45Ti5 and Al45Cu45Ti10 alloys. In the present investigation, we have studied the formation and stability of amorphous phase in Al50Cu45Ti5and Al45Cu45Ti10 rapidly quenched alloys. The DSC curve shows a broad complex type of exothermic overlapping peaks (288- 550†C) for Al50Cu45Ti5 and a well defined peak around 373†C for Al45Cu45Ti10 alloy. In the case of Al50Cu45Ti5 alloy amorphous to icosahedral phase transformation has been observed after annealing at 280†C for 73 h. Large dendritic growth of icosahedral phase along with α-Al phase has been found. Annealing of Al50Cu45Ti5 alloy at 400†C for 8 h results in formation of Al3Ti type phase. Al45Cu45Ti10 amorphous alloy is more stable in comparison to Al50Cu45Ti5 alloy and after annealing at 400†C for 8 h it also transforms to Al3Ti type phase. However, this alloy does not show amorphous to icosahedral phase transformation.