(1. 中南大学材料科学与工程学院，长沙 410083；
2. 中南大学有色金属先进结构材料与制造协同创新中心，长沙 410083)
摘 要: 通过XRD、TEM、EBSD以及拉伸试验研究硅元素对超细晶黄铜力学性能和退火行为的影响。将Cu-20Zn和Cu-20Zn-1.2Si合金在液氮温度(约-196 ℃)下进行轧制并进行退火处理。结果表明：与液氮轧制后Cu-20Zn合金相比，液氮轧制后Cu-20Zn-1.2Si合金的强度显著提升，这是因为加入的硅元素使得层错能降低，使其变形后具有细小的晶粒以及较高的位错和孪晶密度。Cu-20Zn-1.2Si合金热稳定性的提升源自层错能(SFE)的降低以及硅原子与位错的相互作用，使得其内部位错运动受阻。退火后的Cu-20Zn-1.2Si合金优异的强度和塑性的综合力学性能源自其组织内部细小的晶粒、形变孪晶以及大量的退火孪晶和HAGBs的共同作用。
关键字: 铜合金；层错能；力学性能；孪晶；退火行为
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,
Central South University, Changsha 410083, China）
Abstract:The effect of silicon on mechanical properties and annealing behavior of ultrafine-grained (UFG) brasses was investigated in Cu-20Zn and Cu-20Zn-1.2Si alloys by X-ray diffraction (XRD), transmission electron microscope (TEM), electron back scattered diffraction (EBSD) and tensile tests. These two brasses were rolled at cryogenic temperature (about -196 ℃) up to different rolling strains. The results show that the significant improvement of strength in Cu-20Zn-1.2Si alloy is attributed to the formation of fine grains and high densities of dislocations and deformation twins by decreasing the stacking fault energy (SFE). Thermal stability of Cu-20Zn-1.2Si alloy is enhanced due to the reductions of dislocation mobility and grain boundaries migration during annealing by decreasing of SFE and addition of Si. Fine grains, deformation twins and abundant annealing twins are introduced into Cu-20Zn-1.2Si alloy by decreasing the SFE, resulting in a superior strength and ductility combination.
Key words: Cu alloy; stack fault energy; mechanical property; twins; annealing behavior
