摘要
X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were usedto investigate the crystallization process of amorphous Al_(90)TM_xCe_(10-x), (atom fraction inpercent; TM = Fe or Ni; x = 3, 5) alloys. Aging effects were examined by X-ray diffraction. Thestructure corresponding to the prepeak for the amorphous Al_(90)Fe_5Ce_5 alloy is more stable thanthe amorphous matrix, but it is not stable for amorphous Al_(90)Ni_5Ce_5 alloy during the firstcrystallization stage and even decomposes at room temperature. Although both Al-Ni and Al-Fe havestrong chemical bonding, the crystallization onset temperature of amorphous Al-Fe-Ce alloys is muchhigher than that of amorphous Al-Ni-Ce alloys, which is likely caused by the different stability ofthe structure corresponding to the prepeak. The crystallization onset temperature increases as Ce/Niratio increases in amorphous Al_(90)Ni_xCe_(10-x) alloys, whereas it decreases as Ce/Fe ratioincreases in amorphous Al_(90)Fe_xCe_(10-x) alloys. A better atomic packing produces as Ce contentincreases because of the size mismatch in Al-Ni-Ce systems and as Fe content increases because ofthe increasing Fe central structural units.
X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were usedto investigate the crystallization process of amorphous Al_(90)TM_xCe_(10-x), (atom fraction inpercent; TM = Fe or Ni; x = 3, 5) alloys. Aging effects were examined by X-ray diffraction. Thestructure corresponding to the prepeak for the amorphous Al_(90)Fe_5Ce_5 alloy is more stable thanthe amorphous matrix, but it is not stable for amorphous Al_(90)Ni_5Ce_5 alloy during the firstcrystallization stage and even decomposes at room temperature. Although both Al-Ni and Al-Fe havestrong chemical bonding, the crystallization onset temperature of amorphous Al-Fe-Ce alloys is muchhigher than that of amorphous Al-Ni-Ce alloys, which is likely caused by the different stability ofthe structure corresponding to the prepeak. The crystallization onset temperature increases as Ce/Niratio increases in amorphous Al_(90)Ni_xCe_(10-x) alloys, whereas it decreases as Ce/Fe ratioincreases in amorphous Al_(90)Fe_xCe_(10-x) alloys. A better atomic packing produces as Ce contentincreases because of the size mismatch in Al-Ni-Ce systems and as Fe content increases because ofthe increasing Fe central structural units.
基金
This work was financially supported by the Natural Science Foundation of Shandong Province (No. Y2000b02)
