项目名称： 预孪晶-正挤压扭转剪切变形制备高强韧镁合金及组织演变机理研究

项目编号： No.51505143

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 机械、仪表工业

项目作者： 卢立伟

作者单位： 湖南科技大学

项目金额： 20万元

中文摘要： 传统的镁合金塑性加工方法存在细晶均匀性、织构弱化及强化相析出等难以控制问题，致使其强韧性能偏低，严重制约了变形镁合金的大规模发展与广泛应用。本项目拟采用预孪晶-正挤压扭转剪切变形方法调控纳微组织结构，提高镁合金的强韧性能。首先，采用数值模拟分析，初步优化工艺参数。其次，选择合理的参数进行预孪晶-正挤压扭转剪切变形实验及组织演变研究，阐明变形条件对晶粒细化、织构弱化、沉淀相析出和组织稳定性的影响及其机制；揭示预孪晶、沉淀相和动态再结晶之间的相互作用机理；确立晶粒细化、织构弱化与沉淀相析出的调控原理及方法；构建预孪晶-正挤压扭转剪切变形镁合金的强韧化机理模型。最后，结合模拟仿真分析与实验结果，完善预孪晶-正挤压扭转剪切变形工艺和强韧化理论，形成技术原型。本项目的开展，可高效低成本的获得高强韧变形镁合金，对丰富强韧化理论以及变形技术的推广应用具有重要的学术意义和工程价值。

中文关键词： 镁合金；塑性变形；组织演变；强韧性能

英文摘要： The main problem with the conventional plastic working method of Mg alloys lies with the difficulty to govern the evenness of fine crystals, texture weakening, and precipitation of strengthening phase, thereby lowering the strength and toughness of Mg alloys. These drawbacks restrain the mass development and wide application of processed Mg alloys. In this project, we apply a pre-twinning method by adding forward extrusion and torsion deformation, aiming at controlling the nano-micro structure and improving the strength and toughness of Mg alloys. We first use numerical simulation analysis to optimize the process parameters. The pretwinning-forward extrusion and torsion deformation are then carried out using the predicted parameters. The microstructure evolution is investigated to shed light on the effects of deformation process on grain refinement, texture softening, precipitates and microstrusture stability. In addition, we also provide the underlying origin of the pre-twinning, precipitates and dynamic recrystallization, and uncover the controling principles of grain refinement, texture softening, precipitates. A fitting model of strengthen-toughening theory for this new deformation technique will be established. Finally, by combining the numerical simulation with experiments, we further establish a strengthening and toughening theory based on the results. This study could add new knowledge to the understanding of the high-toughness magnesium alloys, and pave way for the establishment of the strengthen-toughening theory, thereby promoting the application of this deformation technique to Mg alloys.

英文关键词： Magnesium alloys;Plastic deformation;Microstructure evolution;Strength and toughness