Deformation microstructure and properties control of Cu-0.6Cr alloy in cryo-equal channel angular pressing

Abstract

Cu-0.6Cr alloy was extruded by liquid nitrogen cooling equal channel angular pressing (ECAP) route-Bc and aging treated at 400 °C–500 °C; the structure and orientation distribution of the alloy were detected by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), electron back-scattered diffraction (EBSD) and TEM. The purpose is to detect the influence of deformation conditions and aging treatment on the microstructure and properties of the materials, and to analyzed the microscopic mechanism of the precipitates formation process and transformation. The results show that the cryo-ECAP-Bc deformation will accelerate the interaction between the microstructure and texture of the Cu-0.6Cr alloy, and reduce the limitation size of the grains after deformation. Strain increase can promote increasing the amounts of micro/nano precipitates discontinuous distribution on the grain boundaries. After 4 passes of extrusion and aging at 450 °C, the tensile strength, hardness and elongation of the material reach to 555.0 MPa, HV 167.3 and 13.1%, respectively, and the conductivity exceeds 84%IACS. The synergistic effect of microalloying, solid solution, cryo-ECAP and aging, and the formation of {111} <112> and {111} <110> textures are beneficial to improving the conductivity of the alloy simultaneously.

摘要

对CuCr合金进行液氮冷却ECAP-Bc路径4道次挤压及时效处理(400 °C~500 °C), 采用OM、 SEM、EDS、XRD及EBSD检测合金组织结构和取向演变, 探索变形条件及时效处理对材料组织性能 的影响规律, 分析析出相形成与转变的微观机制。结果表明, 超低温ECAP-Bc变形会加剧Cu-0.6Cr 合 金组织与织构的交互作用, 减小变形后的极限晶粒尺寸, 变形量的增加会促使微/纳析出相数量的增加 且在晶界上不连续分布; 4 道次挤压和450 °C 时效后材料的抗拉**度、硬度和伸长率分别达到 555.0 MPa、HV 167.3 和13.1%, 导电率超过84%IACS。微合金化、固溶、超低温ECAP, 时效协同作 用及{111}<112>和{111} <110> 织构的形成有利于材料导电性能的同步提升。