轧制形变热处理对Cu-Ni-Si系合金性能和微结构的影响

Effect of Rolling Deformation and Heat Treatment on Properties and Microstructures of Cu-Ni-Si Alloy

对比了Cu-Ni-Si合金二次固溶态(790℃×120 min)和大变形冷轧(98.42%累积变形量)+二次时效态(420℃×480 min)的强度、硬度、导电率等性能的变化规律,分析了两种不同形变热处理工艺状态下合金的显微组织和断口形貌。结果表明:大变形冷轧+二次时效工艺条件下制备的合金平均晶粒尺寸为4.28μm;析出相主要由Cr3Si与Ni2Si构成,平均尺寸分别为65 nm和11 nm,呈弥散分布,且合金内出现大量纳米孪晶。累积大变形产生的形变强化和弥散分布的纳米级析出相形成的析出强化,以及大量纳米孪晶的形成,是Cu-Ni-Si合金力学性能显著提升的主要因素。大变形冷轧+二次时效处理后的合金导电率、硬度、抗拉强度、屈服强度分别为27.2%IACS,HV 231.98,707 MPa,703MPa,较二次固溶态合金分别提升了32.60%,94.67%,204.74%,575.96%。二次固溶态合金断口形貌主要由大而深的韧窝组成,大变形冷轧+二次时效态合金断口形貌主要由小而浅的韧窝组成,数量较多,分布致密。

This article compares the changes in strength,hardness,and electrical conductivity of Cu-Ni-Si alloys in the secondary solid solution state(790℃×120 min)and the severe cold-rolled state(with a cumulative strain of 98.42%)followed by secondary aging(420℃×480 min).It also analyzes the microstructure and fracture morphology of alloys under these two different thermomechanical treatment processes.The results show that the average grain size of the alloy prepared under these process conditions is 4.28μm.The precipitated phases are primarily composed of Cr3Si and Ni2Si,with average sizes of 65 nm and 11 nm,respectively,and they are distributed in a dispersed manner.Moreover,a large number of nano-twins are present within the alloys.The significant improvement in the mechanical properties of Cu-Ni-Si alloy is mainly attributed to the strain hardening caused by the accumulated large deformation,the precipitation strengthening resulting from the dispersed distribution of nano-sized precipitates,and the formation of a substantial amount of nano-twins.After undergoing heavy deformation cold rolling and secondary aging treatment,the electrical conductivity,hardness,tensile strength,and yield strength of the alloys are respectively:27.2%IACS,HV 231.98,707 MPa,and 703 MPa.Compared to the alloy in the secondary solution state,its performance has increased by 32.60%,94.67%,204.74%,and 575.96%respectively.The fracture morphology of the alloy in the secondary solution state is mainly composed of large and deep dimples,while the fracture morphology of alloy in the severe cold-rolled+secondary aged state is mainly composed of small and shallow dimples,which are more numerous and densely distributed.