Devitrification of rapidly quenched Al-Cu-Ti amorphous alloys

摘要

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 Al_(50)Cu_(45)Ti_5 and Al_(45)Cu_(45)Ti_(10) alloys. In the present investigation, we have studied the formation and stability of amorphous phase in Al_(50)Cu_(45)Ti_5 and Al_(45)Cu_(45)Ti_(10) rapidly quenched alloys. The DSC curve shows a broad complex type of exothermic overlapping peaks (288-550 deg C) for Al_(50)Cu_(45)Ti_5 and a well defined peak around 373 deg C for Al_(50)Cu_(45)Ti_5 alloy. In the case of Al_(50)Cu_(45)Ti_5 alloy amorphous to icosahedral phase transformation has been observed after annealing at 280 deg C for 73 h. Large dendritic growth of icosahedral phase along with alpha-Al phase has been found. Annealing of Al_(50)Cu_(45)Ti_5 alloy at 400 deg C for 8 h results in formation of Al_3Ti type phase. Al_(45)Cu_(45)Ti_(10) amorphous alloy is more stable in comparison to Al_(50)Cu_(45)Ti_5 alloy and after annealing at 400 deg C for 8 h it also transforms to Al_3Ti type phase. However, this alloy does not show amorphous to icosahedral phase transformation.