Al2O3-TiC/Cu基复合材料原位反应机理及电弧侵蚀、协调变形行为研究

Due to the poor arc erosion resistance and coordinated deformation ability, difficult-to-machine and complex production process, the production cost of Al2O3/Cu dispersion strengthened alloy is always too high, seriously restricting its wide application. In view of the bottleneck problem-poor erosion resistance and coordinated deformation ability existing in dispersion strengthened alloys, the Al2O3-TiC/Cu dispersion strengthened alloy with Al2O3 and TiC phase were designed and prepared in this project. Base the thermodynamics and kinetics of a serial of synthetical reactions in Cu-Al-TiO2-C system, the fabrication process of the composites were formulated through melting and casting technique. The following researches, the control of preparation repeatability, arc erosion resistance and coordinated deformation behaviors, will be conducted by XRD, TEM, HREM, 3DAP, dynamic tension in-situ observed by SEM/TEM, and numerical simulation. On the basis of obtained results, the principle of multi-phase microstructure designed though the research of arc erosion resistance and coordinated deformation. The systematical researches in this proposal can give a good instruction on the further development, processing and application of the advanced multi-phase dispersion strengthened copper alloys, and better to study the arc erosion resistance and coordinated deformation mechanism and other key scientific issues in multi-phase dispersion strengthened copper alloys.

由于Al2O3/Cu弥散强化铜合金抗电弧侵蚀及协调变形性能差，加上生产工艺复杂使得该类合金生产成本较高，从而限制了其应用。本项目针对上述瓶颈问题，在Cu-Al-TiO2-C体系中原位自生Al2O3-TiC/Cu基复合材料的反应热力学及动力学机理的基础上，采用真空熔铸法原位自生制备Al2O3-TiC/Cu基复合材料。充分利用多相之间的相互作用，使Al2O3-TiC/Cu基复合材料兼具有良好的强度、抗电弧侵蚀和协调变形能力等特征。本项目拟采用XRD、TEM、HRTEM、3DAP显微组织精细表征、SEM/TEM动态拉伸原位观察和数值模拟等方法，对合金进行可控制备。通过研究掌握多相铜合金电弧侵蚀、协调变形行为，提出复合材料电弧侵蚀、协调变形的理论预测模型，同时对研究多相复合材料制备及协调变形、抗电弧侵蚀等共性关键科学问题也具有重要的科学意义。

现有的Al2O3/Cu复合材料在耐高温、高压、大电弧载荷性能上不足，而TiC粒子具备优良的高温强度和抗磨损性能，因此TiC作为增强相加入Al2O3/Cu复合材料中在导电、高温、磨损等恶劣环境中具有潜在的利用价值。项目以Al2O3-TiC为增强相，采用三种方法制备Al2O3-TiC/Cu复合材料。首先通过热力学计算，在Cu-Al-TiO2-C体系下通过放电等离子烧结制备原位自生Al2O3-TiC/Cu复合材料，分别分析（Al+TiO2+C）的添加量、稀土氧化物CeO2的添加量以及烧结温度对Al2O3-TiC/Cu复合材料组织与性能的影响，建立热加工本构方程。随后通过外加法制备Al2O3-TiC/Cu复合材料，对比两种制备方法对Al2O3-TiC/Cu复合材料组织和性能的影响，同时探讨不同制备方法下复合材料的摩擦磨损和热变形行为，建立摩擦磨损模型和塑性变形机制。最后采用新型球磨还原法工艺以还原CuO或Cu2O的方式来制备纳米铜粉及Al2O3-TiC纳米颗粒，阐明还原热力学及动力学，并就球磨还原工艺和不同强化相含量对复合材料导电、硬度、压缩和抗高温软化性能的影响进行讨论。结果表明原位自生法制备的Al2O3-TiC/Cu复合材料的致密度、硬度和导电率要高于外加法；CeO2能改善Cu基体的表面张力，增大与Al2O3和TiC颗粒的界面结合强度，并且起到细化晶粒的作用；建立了Al2O3-TiC/Cu基复合材料的压缩流变应力本构方差，计算出其热激活能为Q=361.161KJ/mol；载荷一定时，随Al2O3-TiC的增加，复合材料的磨损表面由粗糙变得相对光滑完整，摩擦性能提高；随载荷增加，复合材料磨损严重；低温下CO还原获得的Al2O3-TiC/Cu复合粉可以较好地继承前驱粉CuO-(Al2O3-TiC)复合粉的颗粒尺度；前驱粉体在低温下CO还原过程中经历了三个阶段：缓慢反应前期阶段、加速反应阶段以及缓慢反应后期阶段；该工艺下烧结的Cu-10 vol.% (Al2O3-TiC)复合材料显微硬度可达到209 HV，最大压缩强度932 MPa，导电率55 %IACS。项目对开发铜基复合材料规模化生产技术具有实际指导意义，对发展高性能铜基复合材料具有重要科学价值。