热处理对Cu-Ni-Cr-Si合金性能提升的机理研究

Study on Mechanism of Alloys Properties Improvement of Cu-Ni-Cr-Si by Heat Treatment

为了深入了解Cu-Ni-Cr-Si系列合金的综合性能,对比分析了Cu-Ni-Cr-Si合金热处理前后合金的显微硬度、拉伸性能以及显微组织等的变化规律。研究发现,热处理后的Cu-Ni-Cr-Si合金的拉伸性能明显提升,显微硬度也呈现出相同的变化趋势。Cu-Ni-Cr-Si合金是典型的沉淀时效强化合金,热处理过程中溶质原子扩散,从而形成析出相,细小、弥散的析出相分布在合金的晶界中会阻碍位错运动,从而提高了合金的力学性能。显微组织研究发现,热处理后晶粒的尺寸显著变大,与此同时热驱动力促使析出相生成,一般为Ni/Si相和Cr/Si相,析出相具有较高的硬度,合金的显微硬度在热处理之后也会有显著提升。电子背散射衍射(EBSD)分析发现,热处理之后小角度晶界转变为大角度晶界,局域取向差降低,推断位错密度降低。除此之外,溶质原子Cr、Ni、Si从基体中析出,对基体具有一定的净化作用,导电率由29.665%IACS提高到35.124%IACS。

In order to deeply understand the comprehensive properties of Cu-Ni-Cr-Si series of alloys,the changes of the microhardness,tensile properties and microtissue of the Cu-Ni-Cr-Si alloy were also analyzed.It is found that the tensile properties of Cu-Ni-Cr-Si alloy after heat treatment is significantly improved,and the microhardness also show the same change trend.Cu-Ni-Cr-Si alloy is a typical precipitation aging strengthening alloy.During heat treatment,solute atoms diffuse to form precipitates,fine and dispersed precipitates are distributed in the grain boundary of the alloy,which hinder the dislocation movement,so as to improve the mechanical properties of the alloy.The microstructure study shows that the grain size increases significantly after heat treatment,and a large number of precipitates are formed at the same time,generally Ni/Si phase and Cr/Si phase.The precipitates have high hardness,the microhardness of the alloy also increases significantly after heat treatment.Electron backscatter diffraction(EBSD)analysis shows that after heat treatment,the small angle grain boundary changes to the large angle grain boundary,the local orientation difference decreases,and it is inferred that the dislocation density decreases.In addition,the solute atoms Cr,Ni and Si precipitate from the matrix,which has a certain purification effect on the matrix,and the conductivity increases from 29.665%IACS to 35.124%IACS.