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室温下采用等径弯曲通道变形(Equal Channel Angular Pressing,ECAP)C方式进行了纯铜(99.95%)12道次挤压变形。通过等温和等时退火,研究ECAP变形后铜的退火行为,并研究了等径弯曲通道变形和退火后纯铜的显微硬度和显微结构变化。分析了ECAP应变量、退火时间和退火温度对超细晶铜的再结晶行为、抗软化性能的影响。结果表明:ECAP变形后的超细晶铜在退火过程中,表现出不连续再结晶现象;ECAP降低了铜的热稳定性,变形道次越高再结晶温度越低。退火后稳态晶粒尺寸随变形道次的增加而细化,硬度值随变形道次的增加而增大,回归分析表明,晶粒尺寸与硬度之间的关系符合Hall-Petch公式。
Pure copper (99.95%) 12-pass extrusion was performed at room temperature using Equal Channel Angular Pressing (ECAP) C method. The isothermal annealing and isochronal annealing were used to study the behavior of copper after ECAP deformation. The microhardness and microstructure of pure copper after ECAP deformation and annealing were studied. The effects of ECAP strain, annealing time and annealing temperature on recrystallization behavior and softening resistance of ultrafine copper were analyzed. The results show that the ultrafine copper after ECAP deformation shows discontinuous recrystallization during the annealing process. ECAP decreases the thermal stability of copper. The higher the deformation pass is, the lower the recrystallization temperature is. After annealing, the grain size of steady state was refined with the increase of deformation pass, and the hardness value increased with the increase of deformation pass. Regression analysis showed that the relationship between grain size and hardness accorded with Hall-Petch formula.