| The changes of thermal stability (crystallization temperature) and microstructure during annealing of amorphous Al-Ni-Ce-X(Cu, Zr) alloy ribbons have been studied by a combination of differential scanning calorimetry, transmission electron microscopy and X-ray diffractometry. In the case of Al_(88)Ni_8Ce₂Cu₂, 1st crystallization temperature decreased about 17℃ and 2nd crystallization temperature decreased about 22℃ compared to Al_(88)Ni_(10)Ce₂, Al particles were refined from 10 ㎚ to 5 ㎚. These changes are presumably due to an impairment of the amorphous formative ability by a decrease of constituent elements in the remaining amorphous phase resulting from the addition to Cu which is soluble in Al phase. In the case of Al_(88)Ni_(7.5)Ce₂Zr_(2.5), crystallization temperatures increased respectively about 9℃ and 17℃ and Al particle size was hardly changed. This improvement of thermal stability is presumably due to the suppress of crystallization by the addition of Zr which atomic radius is about 10% larger than that of Al and is nearly insoluble in Al and has low diffusivity. Consequently, Cu is concluded to be an effective element to refine Al particle and Zr is concluded to be an effective element to improve thermal stability. When Cu and Zr were added simultaneously in Al-Ni-Ce alloying system, in the case of Al_(87)Ni_8Ce₂Cu₂Zr₁, thermal stability increased and Al particle size decreased. In the case of Al_(85)Ni_8Ce₂Cu₂Zr₃, thermal stability and Al particle size is increased. |
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