电阻法探索Cu_36Zr_48Al_8Ag_8非晶晶化行为及熔体过热对其GFA与热稳定性的影响

Exploration of crystallization behavior of Cu_(36)Zr_(48)Al_8Ag_8 amorphous alloy and melt overheating on its GFA and thermal stability by electrical resistivity measurement

利用四电极电阻法探索Cu36Zr48Al8Ag8非晶合金的晶化行为,以及熔体过热温度对其玻璃形成能力(GFA)和热稳定性的影响.结果显示:除文献中曾揭示的低温阶段晶化之外,该非晶合金在更高温度还发生第二阶段晶化.结合差示扫描量热仪(DSC)、X射线衍射仪(XRD)手段分析表明,第一阶段晶化产物为Cu10Zr7+AgZr亚稳相,它们在第二阶段晶化过程中转变为平衡相CuZr2+AlCu2Zr+CuAl2.当熔体过热度≥430 K时,所获非晶的热稳定性显著下降;并且第一阶段晶化行为发生改变,首先析出准晶.另外,随熔体过热度增大,其玻璃形成能力呈现先增强后减弱的趋势.就熔体过热对非晶热稳定性及玻璃形成能力的作用,本文从熔体结构均匀性和氧化程度两方面进行了分析讨论.

The crystallization behavior of Cu36Zr48AlsAg8 amorphous alloy and the melt overheating on its glass-forming ability （GFA） and thermal stability are explored by the high-temperature four-electrode electrical resistivity method. The results show that this amorphous alloy has a high-temperature crystallization stage which has not been revealed in the previous literatures besides the low- temperature crystallization stage. The crystallization products of the first stage are AgZr and CuloZr7 metastable phases by using differential scanning calorimetry （DSC） and X-ray diffractometry （XRD）. They transform into equilibrium phases CuZr2, AICu2Zr and CuA12 in the second stage crystallization. On one hand, when the overheating temperature is greater than 430 K, the thermal stability of Cu36Zr48A18Ag8 amorphous alloy decreases significantly, and the first stage crystallization behavior changes and the quasicrystals precipitate firstly. On the other hand, its glass-forming ability firstly increases and then decreases with the melt overheat increasing. The effect of the melt overheating on the glass-forming ability and the thermal stability of amorphous are analyzed and discussed from two aspects of melt structure homogeneity and the degree of oxidation.