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