单晶Cu等通道转角挤压A路径形变特征及力学性能

发布时间：2018-05-03 08:30

本文选题：单晶Cu + 等通道转角挤压　；参考：《金属学报》2017年08期

【摘要】：采用XRD、EBSD和TEM技术对单晶高纯Cu(99.999%)经等通道转角挤压(ECAP)A路径过程中的形变织构进行了研究,测试了ECAP后单晶Cu的力学性能和导电性能,并分析了变形过程中织构演变机理及其对力学性能和导电性能的影响。结果表明:原始单晶Cu经2道次变形后,晶内出现了微小的等轴状形变结构;4道次变形后,形成了(110)取向一致的形变带结构;8道次变形后,单晶组织开始破碎,晶粒取向又逐渐趋于(111)面,形成了{111}110和{111}112织构及较弱的{001}100再结晶织构。中、低应变下,形成稳定取向的{hkl}110织构,可有效降低晶界对电子的散射作用,使电导率略有增加,同时有利于大幅度提高材料的加工硬化率。单晶Cu变形初始阶段形成了大量小角度晶界,随着应变的增加,小角度晶界逐渐向大角度晶界转变。由于变形过程中位错积聚及晶界密度增加对位错运动起到阻碍作用,3道次变形后,抗拉强度从168 MPa增加至400 MPa,延伸率从63%减小至27.3%,在随后的变形中抗拉强度增加缓慢,延伸率略有回升。前8道次变形中硬度不断增加,8道次变形后出现了再结晶,导致随后的挤压过程中硬度不稳定。
[Abstract]:The deformation textures of monocrystalline high-purity Cu (99.999) during the process of equal-channel angular extrusion (ECAP) were studied by using XRDD-EBSD and TEM techniques. The mechanical properties and electrical conductivity of single crystal Cu after ECAP were tested. The mechanism of texture evolution during deformation and its influence on mechanical properties and electrical conductivity were analyzed. The results show that after 2-pass deformation of the original single crystal Cu, there is a tiny equiaxed deformed structure in the crystal after 4 times of deformation, and the deformation band structure with the same orientation is formed after 8 passes of deformation, and the single crystal structure begins to break. The grain orientation tends to the surface of 111), forming {111} 110 and {111} 112 texture and weak {001} 100 recrystallization texture. The formation of {hkl} 110textures with stable orientation at medium and low strain can effectively reduce the scattering of electrons by grain boundaries, increase the conductivity slightly, and increase the work hardening rate of the materials by a large margin. A large number of small angle grain boundaries were formed during the initial deformation of single crystal Cu, and with the increase of strain, the small angle grain boundaries gradually changed to large angle grain boundaries. Due to the effect of dislocation accumulation and grain boundary density increasing on dislocation movement during deformation, the tensile strength increases from 168 MPa to 400MPa, and the elongation decreases from 63% to 27.3MPA, and the tensile strength increases slowly during subsequent deformation. Elongation picked up slightly. The hardness of the first 8 passes is increased continuously and the recrystallization occurs after the 8 pass deformation, which leads to the instability of the hardness in the subsequent extrusion process.
【作者单位】：兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室;兰州理工大学有色金属合金及加工教育部重点实验室;
【基金】：国家自然科学基金项目No.51261016~~
【分类号】：TG146.11;TG379

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