摘要
用自制的高能球磨机将Cu-Ti和Ni-Ti二元系的纯金属粉末混合物制成了非晶粉末,确定了用机械合金化制取非晶含金粉末的一般工艺条件。用X射线衍射(XRD)方法研究了机械合金化时的非晶化过程。通过高温XRD和热差分析(DTA)方法检测了非晶粉末的晶化行为。实验发现,球料比应加以限制,在我们的实验条件下10:1是较适当的,机械合金化过程可能保存的少量层状结晶相通过随后在低于晶化温度T_X下的加热可能转化成非晶相。Cu_(43)Ti_(57)非晶粉末的T_X约等于450℃,Ni_(45)Ti_(55)约等于500℃。计算了Cu-Ti二元系在300℃时亚稳相和平衡相的自由能曲线,并根据扩散偶的模型讨论和解释了机械合金化的非晶化过程。
Amorphous binary Cu-Ti and Ni-Ti powders could be produced by mechanical alloying of elemen- tal powders in a high-energy ball mill, and the process parameters used were presented. X-ray diffrac- tion (XRD) was used to follow the progress of the mechanical alloying. The crystallization behavior of amorphous powders was measured by XRD at high temperature up to 800℃ and differential ther- mal calorimetry (DTA). It was found that the ball-to-powder weight ratio should be limited and 10: 1 was favourable in this study, and that a small part of layered crystalline phase which might be re- maining during processing was possible to be transformed to amorphous phase by subsequent heat treat- ment below crystallization temperature T_x, and the T_x of Cu_(43)Ti_(57) and Ni_(45)Ti_(55) amorphous powders were about 450℃ and 500℃ respectively. The free energy curves of the metastable and equilibrim phases at 300℃ for binary Cu-Ti system were calculated and a schematic illustration based on the mode of diffusion couples was proposed to explain the amorphization process produced during milling.
基金
中国有色金属工业总公司高技术基金
国家教委博士点基金
关键词
CU-TI
NI-TI
粉末
非晶化
机械
amorphization
mechanical alloying
crystallization temperature
free energy
diffusion couple
