熔体结构变化对Al85Ni5Y8Co2非晶合金晶化行为的影响

采用四电极电阻法研究Al85Ni5Y8Co2合金熔体电阻率,并结合X射线衍射仪(XRD)和差示扫描量热仪(DSC)探索熔体结构变化对Al85Ni5Y8Co2非晶晶化行为的影响。结果表明:Al85Ni5Y8Co2合金在1135~1357 K温度区间内发生熔体结构变化,而熔体结构变化导致Al85Ni5Y8Co2非晶晶化行为存在差异;在熔体温度为1673 K下制备的非晶薄带第一晶化较1323 K和1523 K的明显提前,对激活能的计算证实其初晶化更容易析出FCC-Al,且更难析出Al2Y3、Al13Co4、Al9Co2和AlNi等脆性金属间化合物;通过XRD的测试发现高的熔体温度可能会导致熔体中原子团簇的破坏,从而引起非晶晶化行为的改变。

Effect of melt structure transition on crystallization behavior of Al85Ni5Y8Co2 amorphous alloys

The electrical resistivity of Al85Ni5Y8Co2 melt was studied by four-electrode electrical resistivity method.The effect of melt structure transition on the crystallization behavior of Al85Ni5Y8Co2 amorphous alloys was investigated by both X-ray diffractometer(XRD)and differential scanning calorimetry(DSC)measurements.The result shows that the melt structure of Al85Ni5Y8Co2 alloy changes within temperature range from 1135 K to 1357 K.The crystallization behavior of Al85Ni5Y8Co2 amorphous alloys is different due to the change of melt structure:the first crystallization of amorphous ribbon prepared at 1673 K is obviously earlier than that prepared at 1323 K and 1523 K.The calculation of activation energy confirms that the primary crystallization of Al85Ni5Y8Co2 alloy is easier to precipitate FCC-Al and harder to precipitate brittle intermetallic compounds,such as Al2Y3,Al13Co4 and AlNi.The XRD measurements show that high melt temperature may lead to the destruction of atomic clusters in the melt,which may lead to the change of crystallization behavior.