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采用静平衡凝固技术制备了Cu含量为90wt%、不同Ni/Si原子比的Cu-Ni-Si合金,采用扫描电镜(SEM)、能谱分析(EDS)和X射线衍射仪(XRD)对合金的显微组织和相组成进行了分析,利用差热分析(DSC)考察了合金熔体在冷却过程中的相转变行为。研究结果表明,Ni/Si原子比对Cu-Ni-Si合金显微组织的影响可归因为α-Cu晶粒内部析出的δ-Ni2Si相数量的变化和晶界相在Cu-Si和Ni-Si化合物之间的选择。δ-Ni_2Si相数量的变化与初生α-Cu内部Ni、Si原子的浓度密切相关,而晶界相的相选择则是Cu-Si和Ni-Si金属间化合物相之间竞争的结果。随着Ni/Si原子比的增加,残余液相中Ni原子浓度增加增高,具有更负形成焓Ni-Si金属间化合物逐渐从竞争中胜出,导致晶界相从Cu-Si化合物向Ni-Si化合物的转变。
Cu-Ni-Si alloys with Cu content of 90wt% and different atomic ratio of Ni / Si were prepared by static equilibrium solidification technique. The microstructure of Cu-Ni-Si alloy was characterized by SEM, EDS and XRD The microstructure and phase composition of the alloy melt were investigated by differential thermal analysis (DSC). The phase transition behavior of the alloy melt during cooling was investigated. The results show that the effect of Ni / Si atomic ratio on the microstructure of Cu-Ni-Si alloy can be attributed to the change of the amount of δ-Ni2Si phase precipitated in α-Cu grain and the change of grain boundary phase in Cu-Si and Ni- Si compound choice between. The change of the amount of δ-Ni_2Si phase is closely related to the concentration of Ni and Si atoms in the primary α-Cu, while the phase selection of the grain boundary phase is the result of competition between the Cu-Si and Ni-Si intermetallic phases. As the Ni / Si atomic ratio increases, the Ni atom concentration in the residual liquid phase increases with the more negative enthalpy of formation Ni-Si intermetallic compounds gradually out of competition, leading to the transition from the Cu-Si compound to the Ni-Si compound Compound transformation.