微量铬强化B10合金形变热处理后的组织及性能

利用真空感应熔炼-铸造工艺制备了微量铬强化的B10合金(即Cu-10Ni-0.3Cr(mass%)合金),并对铸态合金进行固溶、冷变形及退火处理,采用光学显微镜、拉伸测试和四线制测量法等研究了不同处理状态下Cu-10Ni-0.3Cr合金的显微组织、力学性能和电导率。结果表明,铸态Cu-10Ni-0.3Cr合金晶粒为等轴状,晶粒中均匀分布着黑色颗粒状析出相;再结晶退火后合金的组织均匀细小,晶粒内有明显的退火孪晶。铸态合金的导电性最好,电导率为17.15%IACS,900℃固溶2 h后合金的导电性最差,电导率为12.30%IACS。冷轧态(50%变形量)合金的强度、硬度最高,分别为340 MPa、112 HB,延塑性最差,伸长率只有8%;再结晶退火态合金综合力学性能最好;随着退火温度升高,冷轧态合金形变组织逐渐消失,且退火温度愈高,形变组织消失得愈明显,同时晶粒在退火过程中发生长大,最终导致合金强度、硬度降低,塑性增加。

Microstructure and properties of trace Cr reinforced B10 alloy after deformation and heat treatment

A trace-chromium-reinforced B10 alloy(i.e.,Cu-10 Ni-0.3 Cr(mass%)alloy)was prepared by a vacuum induction melting-casting process,and the as-cast alloy was subjected to solid solution,cold rolling and annealing treatment.Microstructure,mechanical properties and electrical conductivity of the Cu-10 Ni-0.3 Cr alloy under different heat treatment conditions were studied by means of optical microscope,tensile test and four-wire system.The results show that the grains of the as-cast Cu-10 Ni-0.3 Cr alloy are equiaxed,and black granular precipitates are uniformly distributed in the grains.The microstructure of the alloy after the recrystallization annealing is uniform and small,and the grains have obvious annealing twins.The conductivity of the as-cast alloy is the best,which is 17.15%IACS,the conductivity of the alloy after solid solution treatment at 900℃for 2 h is the worst,which is 12.30%IACS.The strength and hardness of the alloy after cold rolling with 50%deformation are the highest,which are 340 MPa and 112 HB,respectively,the ductility is the worst,the elongation is only 8%,and the comprehensive mechanical properties of the alloy after cold rolling and recrystallization annealing are the best.With the increase of the annealing temperature,the deformed microstructure of the cold rolled alloy gradually disappears,and the higher the annealing temperature,the more obvious the disappearance of deformed microstructure.The grain growth occurs during annealing,which leads to the decrease of strength,hardness and the increases of plasticity of the alloy.