高强高导Cu-Cr-Zr合金组织和性能的研究

发布时间：2018-11-28 07:43

【摘要】：高强高导Cu-Cr-Zr合金广泛应用于集成电路引线框架、高速铁路电气接触线以及航空航天等众多领域。现代工业技术的不断发展,对高强高导铜合金性能的要求也越来越高。这就需要我们及时开发出新的Cu-Cr-Zr合金以及与之配套的加工技术,并深入探讨合金组织的成因与性能变化规律。本文在Cu-0.81Cr-0.12Zr合金(质量百分比,下同)基础上添加微量稀土La和Y元素,采用真空感应熔炼法制备合金铸锭,经均匀化退火后进行热轧,接着进行固溶、冷轧和时效处理,用光学显微镜和扫描电子显微镜分析了各工艺阶段合金的显微组织,用X射线衍射仪分析了试样的相组成,用高分辨透射电子显微镜分析了时效析出相的结构,用数显硬度计测试了显微硬度,用万能力学试验机测试了强度,用微欧计测定了导电率。同时采用快速凝固单辊旋铸法制备了合金薄带试样,获得了完全过饱和固溶体合金,测试了时效处理前后试样的显微硬度和导电率。此外还采用液态金属冷却定向凝固法制备了Cu-0.81Cr合金棒状试样,考察了合金的组织以及力学与电学性能。主要研究结论如下:Cu-0.81Cr-0.12Zr-0.05La-0.05Y铸锭的相组成不因稀土的加入而改变,均包含Cu、Cr和Cu5Zr三相,其中大部分Cr相以Cr+Cu共晶形态或颗粒状分布于Cu的晶界处,少量Cr颗粒分布于Cu基体内部,Cu5Zr则仅存在于Cu晶界处,但稀土元素的加入可以明显细化铸锭组织。Cu-0.81Cr-0.12Zr-0.05La-0.05Y铸锭在1193 K温度下均匀化退火60分钟后热轧,再于1223 K温度下固溶处理60分钟后冷却至室温进行冷轧,详细考察了不同轧比冷变形合金在系列温度时效不同时间后的性能,发现在冷变形60%、773 K时效处理60分钟优化工艺处理后的试样,其显微硬度达186 HV,导电率达81%IACS。对上述合金进一步施以40%的冷变形,再于723 K时效30分钟,显微硬度提高至203 HV,导电率提升至81.9%IACS,此时的抗拉强度和延伸率分别达604 MPa和8.5%。经过60%冷轧加工的Cu-0.81Cr-0.12Zr-0.05La-0.05Y合金以20 K/min的速率连续加热时,分别于653 K-698 K和743 K-823 K发生沉淀相的集中析出和基体Cu的再结晶。冷轧态Cu-0.81Cr-0.12Zr-0.05La-0.05Y合金微应变值高于纯铜,其XRD图谱中(111)Cu衍射峰强度随着时效温度的升高而不断降低,(220)Cu衍射峰强度则不断增大。Cu-0.81Cr-0.12Zr-0.05La-0.05Y合金在时效过程中析出体心立方的Cr相和面心立方的Cu5Zr相。在最佳综合性能处,部分析出相仍与基体保持共格关系,其中Cr析出相与Cu基体之间呈现Nishiyama-Wassermann位向关系:(111)Cu//(110)Cr;[01_1]Cu//[001]Cr;[2_11] Cu // [1_10] Cr。快速凝固Cu-0.81Cr-0.12Zr-0.05La-0.05Y合金为完全过饱和固溶体,合金在以20 K/min的速率连续加热时,反映过饱和固溶体脱溶和析出相形成的放热峰开始于655 K,结束于688 K。快淬条带在773 K时效15分钟后具有最好的综合性能:显微硬度达215 HV,导电率为77.6%IACS。该显微硬度比60%冷变形后再行时效的合金还高出29 HV,表明快淬时效比常规固溶时效具有更好的强化效果。定向凝固Cu-0.81Cr自生复合材料组织由定向排列的α-Cu枝(胞)晶和分布在其晶界上的Cu+Cr共晶增强体组成。共晶组织中的两相虽然仍为非定向性排列,但定向凝固组织中共晶体沿初生ɑ-Cu晶界纵向分布仍显著提高了定向凝固合金的强度、塑性和导电性。提高定向凝固时的温度梯度,使组织细化,在试样纵向的连续性得到改善,试样的力学和导电性能均提高。但提高抽拉速度,试样强度和导电率均是先升后降,而塑性则先降后升。
[Abstract]:The high-strength and high-conductivity Cu-Cr-Zr alloy is widely used in integrated circuit lead frame, high-speed railway electrical contact line and aerospace and other fields. With the development of modern industrial technology, the requirement of high-strength and high-conductivity copper alloy is also higher and higher. It is necessary for us to develop new Cu-Cr-Zr alloy in time, and to study the cause and performance of the alloy. A trace rare-earth La and Y element are added on the basis of Cu-0.81Cr-0.12Zr alloy (mass percentage, the same below), the alloy ingot is prepared by adopting a vacuum induction melting method, the hot rolling is carried out after the homogenization annealing, and then the solid solution, the cold rolling and the aging treatment are carried out, The microstructure of the alloy in each process stage was analyzed by means of an optical microscope and a scanning electron microscope. The phase composition of the sample was analyzed by an X-ray diffractometer. The structure of the aging phase was analyzed by a high-resolution transmission electron microscope. The microhardness was measured by a digital-display hardness tester. The strength was measured by a universal mechanical testing machine and the conductivity was measured with a micro-ohm meter. The alloy thin strip specimens were prepared by means of the rapid solidification single-roll casting method, and the total supersaturated solid solution alloy was obtained, and the micro-hardness and the conductivity of the samples before and after the aging treatment were tested. In addition, a rod-like sample of Cu-0.81Cr alloy was prepared by liquid metal cooling and directional solidification, and the microstructure and mechanical and electrical properties of the alloy were investigated. The main conclusions are as follows: The phase composition of Cu-0.81Cr-0. 12Zr-0. 05La-0. 05Y ingot is not changed due to the addition of rare-earth, and the phases of Cu, Cr and Cu5Zr are all composed of Cu, Cr and Cu5Zr. Most of the Cr phases are in the form of Cr + Cu or in the grain boundary of Cu, and a small amount of Cr particles are distributed in the Cu matrix, and the Cu5Zr exists only at the Cu grain boundary. but the addition of rare earth elements can obviously refine the ingot structure. Cu-0.81Cr-0. 12Zr-0. 05La-0. 05Y ingot was annealed for 60 minutes at 1193 K temperature for 60 minutes, then cooled to room temperature for cold rolling at 1223 K temperature for 60 minutes, and the properties of different rolling-ratio cold-deformed alloys at different time after the series of temperature aging were investigated, and the cold deformation was found to be 60%. The microhardness of the samples treated with 773K aging treatment for 60 minutes was 186 HV and the conductivity was 81% IACS. The alloy is further subjected to cold deformation of 40%, then the alloy is aged for 30 minutes at 723K, the microhardness is increased to 203 HV, the conductivity is improved to 81.9% IACS, and the tensile strength and the elongation at this time are respectively 604 MPa and 8.5%. The precipitation of the precipitation phase and the recrystallization of the matrix Cu at 653K-698K and 743K-823K were carried out at a rate of 20K/ min by 60% cold-rolling of Cu-0.81Cr-0.12Zr-0.05La-0.05Y alloy at a rate of 20 K/ min. The microstrain of the cold-rolled Cu-0.81Cr-0.12Zr-0. 05La-0. 05Y alloy is higher than that of the pure copper, and the intensity of the (111) Cu diffraction peak in the XRD pattern decreases with the increase of the aging temperature, and (220) the intensity of the Cu diffraction peak is increasing. The Cu-0.81Cr-0.12Zr-0. 05La-0. 05Y alloy precipitates the Cu5Zr phase of the Cr-phase and the surface-centered cubic of the body-centered cubic in the aging process. In the best comprehensive performance, the partial precipitation phase is still in a co-lattice relationship with the matrix, in which the Nishiyama-Wassermann-bit directional relationship is presented between the Cr-out phase and the Cu matrix: (111) Cu// (110) Cr;[01 _ 1] Cu//[001] Cr;[2 _ 11] Cu//[1 _ 10] Cr. The fast-set Cu-0.81Cr-0.12Zr-0. 05La-0. 05Y alloy is a completely supersaturated solid solution, When the alloy is continuously heated at a rate of 20 K/ min, the heat release peak that reflects the desolvation and precipitation phase of the supersaturated solid solution starts at 655 K and ends at 688 K. The fast quenching strip has the best comprehensive performance after the time of the 773 K aging for 15 minutes: the microhardness reaches 215 HV and the conductivity is 70.6% IACS. The microstructure of the alloy after cold deformation of 60% is higher than 29HV, which shows that the hardening time is better than that of conventional solid-solution aging. The directionally solidified Cu-0.81Cr self-growing composite material is composed of a directionally arranged Cu-Cu branch (cell) crystal and a Cu + Cr eutectic reinforcement which is distributed on the grain boundary of the Cu-0. 81Cr self-growing composite material. Although the two phases in the eutectic structure are still non-oriented, the longitudinal distribution of the co-crystals along the primary Cu-Cu grain boundary in the directional solidification structure still significantly improves the strength, plasticity and electrical conductivity of the directional solidification alloy. the temperature gradient at the time of directional solidification is improved, the structure is refined, the continuity of the longitudinal direction of the sample is improved, and the mechanical and electrical conductivity of the sample can be improved. but the pulling speed is improved, the strength and the conductivity of the sample are firstly raised and then decreased, and the plasticity is firstly reduced.
【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG146.11

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