形变热处理对Cu-15Ni-8Sn系合金组织结构与性能的影响

Effect of thermo-mechanical treatment on microstructure and property of Cu-15Ni-8Sn alloy

摘要:

利用力学、电学性能测试，金相显微分析、扫描和透射电镜观察等手段研究均匀化退火和形变热处理工艺对Cu-15Ni-8Sn-1.0Zn-0.8Al-0.2Si合金组织结构与性能的影响。合金铸锭经830 ℃/2h+850 ℃/2h双级均匀化退火处理，热轧变形后合金板材经850 ℃/1h固溶处理，冷轧变形60%后，分别在400 ℃和450 ℃时效处理。当450 ℃时效时间为30 min时，合金硬度为378 HV，电导率8.0% IACS，抗拉强度1144 MPa，屈服强度1098 MPa,延伸率3.29%；在400 ℃时效1 h时，合金硬度为390 HV，电导率7.4% IACS，抗拉强度1164 MPa，屈服强度1112 MPa，延伸率3.05%。合金的强化效应主要来源于调幅分解强化、析出强化和亚结构强化的共同作用，同时，溶质原子的析出使基体固溶度降低，合金电导率提高。合金经双级均匀化退火处理后为均匀的等轴晶组织，在400 ℃/1h时效过程中发生调幅分解，同时析出具有L12结构的β-Ni3Sn析出相，其与Cu基体的晶体取向关系为： ‖ , ‖ ; ‖ , ‖ 。

Abstract:

The effect of homogenizing annealing and thermo-mechanical treatment processes on microstructure and property of Cu-15Ni-8Sn-1.0Zn-0.8Al-0.2Si alloy was investigated using mechanical property test, electrical conductivity measurement, optical microscopy, scanning electron microscopy and transmission electron microscopy. The alloy ingot was two-stage homogenizing annealing treated at 830 ℃/2h+850 ℃/2h, hot rolled by 70%, then solution treated at 850 ℃ for 1 h, followed by 60% cold-rolling deformation and aging treatment at 400 ℃ and 450 ℃ respectively. After aged at 450 ℃ for 30 min, the hardness was 378HV, electrical conductivity was 8.0% IACS, tensile strength was 1144MPa, yield strength was 1098MPa, elongation percentage was 3.29%. During aging at 400 ℃ for 1 h, the hardness was 390 HV, electrical conductivity was 7.4% IACS, tensile strength was 1164 MPa, yield strength was 1112 MPa, elongation percentage was 3.05%. The combined effects of spinodal decomposition strengthening, precipitation strengthening and substructure strengthening were the mainly strengthening mechanism in alloy. Meanwhile, since the precipitation of solute atoms, the solid solubility of matrix was reduced, and the electrical conductivity of alloy was improved. After two-stage homogenizing annealing treatment, the microstructure of alloy was homogeneous equiaxed grain. It was found that spinodal decomposition and L12 ordering (β-Ni3Sn) appeared in the alloy during aging at 400 ℃ for 1h. The crystal orientation relationships between copper matrix and β-Ni3Sn precipitates were determined as: ‖ , ‖ ; ‖ , ‖ .