时效处理对AuCuNi合金的微观结构及力学性能的影响

Effects of Aging Treatment on the Microstructure and Mechanical Properties of AuCuNi Alloy

AuCuNi合金常用在各种低电压轻负荷的滑动电接触环境中做电刷、导电环材料,在时效过程中发生无序-有序相变使得合金硬度显著提高。通过显微硬度测试、X射线衍射分析(XRD)以及透射电镜(TEM)显微分析等方法,研究了不同温度和不同时间时效条件下Au-32Cu-13Ni合金的微观结构及力学性能的变化规律。结果表明,200~250℃温度范围内合金获得的时效硬化效果最佳;250℃时效处理1.5 h后,合金发生α0→AuCuI有序相变,且随着时效时间增加,有序相持续析出,晶格畸变减低,基体α0峰位回归Au(200)的标准峰位附近;经TEM分析确认,合金在250℃下时效5天后析出了具有四方结构的AuCuI(L10)有序相,且在有序化的过程中可能形成孪晶。

AuCuNi alloy is commonly used as brush and conductive ring materials in various low-voltage and light-load sliding electrical contact environments.Disordered-ordered phase transition occurs during the aging process,which significantly increases the hardness of the alloy.Microhardness test,X-ray diffraction analysis(XRD)and transmission electron microscope(TEM)were used to study the microstructure evolution and mechanical properties of the Au-32Cu-13Ni alloy under various aging conditions.The results show that the alloy has the best aging hardening effect in the temperature range of 200~250°C.After aging at 250°C for 1.5 h,the alloy undergoes an ordered phase transition ofα0→AuCuI.As the aging time increases,the ordered phase continues to precipitate,and the lattice distortion is reduced and the matrixα0 peak position returns to near the standard peak position of Au(200).TEM analysis confirmed that the AuCuI(L10)ordered phase with a tetragonal structure precipitated after aging at 250°C for 5 days,and twinning may be formed during the ordering process.