Au-15Cu-10Ni合金时效强化机制研究

The Aging Hardening Mechanism of Au-15Cu-10Ni Alloy

常用作电接触材料的Au Cu Ni合金在时效过程中会得到强化,硬度明显增加。采用真空高频熔炼得到Au-15Cu-10Ni合金,对轧制得到的片材进行不同条件下的时效处理,研究其微观组织、晶体结构和力学性能变化。结果表明,150~250℃范围内时效硬化效果显著,并且随温度升高硬度值提高,时效过程中生成的Au CuI有序相是造成硬度提高的主要原因。在200℃的条件下时效2.78 h后,晶粒表面出现了明显的条纹状,组织发生有序转变;时效时间延长至5 d后有序转变完成,晶体结构由fcc转变为fct结构,晶胞发生体积收缩,导致晶界明显宽化。

AuCuNi alloy, a kind of commonly used electric contact material, can be strengthened, as indicated by an obvious increase of hardness after the aging process. Au-15Cu-10Ni alloy was prepared by high-frequency vacuum smelting. Its sheets directly obtained by rolling were subjected to an aging treatment under various conditions. The changes in microstructure, crystal structure and mechanical properties were observed. The results show hardening effect of the sheet is apparent after aged at 150-250℃ and the hardness increases with temperature rising, mainly due to the formation of AuCuI ordered-phase during the aging process. An obvious stripes of grain surface develop after aged at 200℃ for 2.78 hours, because of an ordering transformation of the microstructure. If the aging time is extended to 5 days, the crystal structure will be transformed from fcc to fct structure through the ordering transformation. And the transformation is accompanied by a shrink in the volume of the crystal cell, resulting in significant broadening of the grain boundary.