Sn及深冷拉拔对Cu-Cr-Zr合金组织和性能的影响

Effects of Sn and cryogenic drawing on microstructure and properties of Cu-Cr-Zr alloys

采用真空铸造的方法制备了不同Sn含量的Cu-Cr-Zr-xSn合金,利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)等检测方法分析了Cu-Cr-Zr-xSn合金在多阶段形变热处理过程中(杆坯→一次拉拔→950℃固溶1 h→二次拉拔→450℃峰时效→室温拉拔/深冷拉拔→450℃退火)微观组织的变化,同时测定了相应的抗拉强度和导电率。重点研究了Sn元素和深冷拉拔对Cu-Cr-Zr合金组织和性能的影响规律。结果表明,添加Sn和深冷拉拔都能够明显提高Cu-Cr-Zr合金的抗拉强度,同时不会对导电率造成太大的损失。其中Sn元素会促进富Cr初生相的形成,在形变热处理过程中,富Cr初生相会被拉成纤维状,起到纤维强化的效果;深冷拉拔则会提高变形抗力,从而导致变形晶粒尺寸更小,同时也能够促使富Cr初生相转变为纤维状,进一步提高合金的强度。

Cu-Cr-Zr-xSn alloys with different Sn contents were prepared by vacuum casting.Optical microscope(OM),scanning electron microscope(SEM)and transmission electron microscope(TEM)were used to analyze the microstructure evolution of the Cu-Cr-Zr-xSn alloys in the process of multi-stage thermo-mechanical treatment(rod blank→first drawing→950℃solution treatment for 1 h→secondary drawing→peak aging at 450℃→room temperature drawing or cryogenic drawing→450℃annealing),and the corresponding tensile strength and conductivity were measured.The effects of Sn element and cryogenic drawing on microstructure and properties of Cu-Cr-Zr alloy were mainly studied.The results show that both the Sn element and the cryogenic drawing can significantly improve the tensile strength of Cu-Cr-Zr alloy without causing too much loss of conductivity,where the Sn element will promote the formation of the Cr-rich primary phase.During the thermo-mechanical treatment process,the Cr-rich primary phase will be drawn into a fiber shape,which has the effect of fibre strengthening.Cryogenic drawing can improve the deformation resistance,resulting in a smaller deformed grain size,and also promote the Cr-rich primary phase to transform into a fibrous shape,which further improves the strength of the alloy.