Deformation Physics of Nanoscale Features in Magnesium Alloys

镁合金纳米级特征的变形物理学

• 批准号: RGPIN-2019-05882
• 负责人: ZHU, GUOZHEN
• 金额: $ 2.77万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=738564
• 关键词: Deformation; Physics; Nanoscale; Features; Magnesium

Magnesium alloys can achieve a high strength-density ratio and thus attract continuous interest over decades in replacing conventional metals for the weight reduction in vehicles and aircrafts. The main impediment to the greater use of magnesium is their poor deformability, originating from the inherent anisotropy of the crystal structure of magnesium. In detail, the activation thresholds for various deformation modes, such as basal-slip, non-basal slip, and twinning, are largely different (i.e., of order 100). With current emphasis on improving the deformability of magnesium alloys while increasing their strength, the key is tuning the relative activities of different deformation modes, mainly through introducing nanoscale features with selective strengthening effects. Alloying with rare earth elements, magnesium shows promise in improving both strength and ductility, however, the involved mechanism is poorly understood due to its complexity, including unclear nanoscale features, their interaction with different deformation modes, and consequent strengthening effects. The five-year objective of the proposed research is to perform a systematic and comprehensive research to gain an adequate understanding of the deformation physics within magnesium alloys at atomic and nano scale. Using state-of-the-art in-situ thermo-mechanical testing and high resolution imaging techniques integrated with electron microscopy, research will be undertaken, with model systems of binary and ternary magnesium-rare earth alloys, in three areas: 1) the effect of rare earth solutes on the structure changes of different dislocations, the main carriers of plastic deformation; 2) the interaction between dislocations and twin boundaries and grain boundaries, containing rare earth segregations; and 3) the selective strengthening effects of solute clusters or fine precipitates with anisotropic morphology. The expected major outputs of this research will be an enhanced understanding of nanoscale features and consequent strengthening effects within magnesium alloys. These results will provide a comprehensive understanding of deformation dynamics at atomic and nano scale in magnesium alloys, and can form a solid foundation for further advancing hexagonal alloys in general. The proposed program will train 3 Ph.D. and 3 master's students, who will gain experience and will generate new knowledge in microstructure design and characterization of light-weight alloys. This work will be of great value to the key industries involved in light-weight alloys, such as General Motors and Magellan Aerospace. Discoveries in the areas of magnesium will help maintain Canada's status as a leader in this research area and in the production of light-weight alloys in aerospace and automotive industries.

镁合金可以达到很高的强度密度比，因此几十年来一直吸引着人们对替代传统金属用于车辆和飞机轻量化的兴趣。镁更广泛应用的主要障碍是镁的变形能力差，这源于镁晶体结构固有的各向异性。具体而言，不同变形模式，如基面滑移、非基面滑移和孪生的激活阈值有很大的不同(即100量级)。随着当前强调在提高强度的同时改善镁合金的变形能力，关键是调整不同变形模式的相对活动，主要是通过引入具有选择性强化效果的纳米特征来实现的。镁与稀土元素合金化，在提高强度和延展性方面显示出良好的前景，但由于其复杂的纳米尺度特征、与不同变形模式的相互作用以及由此产生的强化效应，其机制尚不清楚。拟议研究的五年目标是进行系统和全面的研究，以充分了解镁合金在原子和纳米尺度上的变形物理。利用最先进的原位热机械测试和高分辨率成像技术，结合电子显微镜，将在三个方面进行研究：1)稀土溶质对作为塑性变形主要载体的不同位错结构变化的影响；2)位错与含稀土偏析的孪晶界和晶界的相互作用；3)具有各向异性形态的溶质团或细小析出物的选择性强化效应。这项研究的预期主要成果将是加深对镁合金中纳米级特征和由此产生的强化效应的理解。这些结果将对镁合金在原子和纳米尺度上的变形动力学有一个全面的了解，并为进一步发展六方合金奠定坚实的基础。该计划将培养3名博士生和3名硕士研究生，他们将获得经验，并在轻质合金的微结构设计和表征方面产生新的知识。这项工作将对通用汽车和麦哲伦航空航天等涉及轻质合金的关键行业具有重要价值。镁领域的发现将有助于保持加拿大在这一研究领域以及在航空航天和汽车工业的轻质合金生产方面的领先地位。