Microstructural Tailoring of Ultrafine-Grained Magnesium Alloys for Lightweight Applications

用于轻量化应用的超细晶镁合金的微观结构定制

• 批准号: RGPIN-2018-05826
• 负责人: BoakyeYiadom, Solomon
• 金额: $ 2.04万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=645667
• 关键词: Microstructural; Tailoring; Ultrafine; Grained; Magnesium

There is an increasing demand on the aerospace and automotive industries to reduce weight, fuel consumption and emission of greenhouse gases by using lightweight materials such as Magnesium (Mg) and Aluminum (Al). Also, lightweight materials, that are resistant to shock loading, are needed in protective vehicles and personnel armour to prevent injury. Magnesium (Mg) is the lightest metal and Mg alloys are desired for lightweight applications due to their low density (~1738 kg/m3, ~35% < Al). However, Mg alloys exhibit poor formability, moderate strength and limited ductility due to their hexagonal close-packed crystal structure. ******Ultrafine-grained (UFG) materials (grain sizes ~≤ 1000 nm) possess unique microstructure-dependent properties superior to coarse-grained materials. They are produced through grain refinement and have enhanced properties such as high strength and fracture toughness. Severe Plastic Deformation (SPD) techniques such as high pressure torsion can be used to produce bulk UFG Mg alloys with exceptional strength, fracture toughness and ductility. During SPD, very high strains (true strain ≥1) are imposed on a bulk material leading to exceptional grain refinement without significant change to the overall dimensions of the material. Also, large amounts of lattice defects such as grain boundaries and dislocations are formed that improve the deformation behavior of the materials.******This research implements a synergistic approach involving the development and comprehensive physical, mechanical and microstructural characterization of UFG Mg alloys. Bulk UFG Mg alloys will be developed and mechanisms that occur during the evolution of ultrafine grains and lattice defect structures in the alloys will be studied. The mechanism/s that occur during grain refinement, their effect on the evolved microstructure and optimum processing conditions will also be studied. The dynamic mechanical properties, deformation behavior and mechanism of damage of UFG Mg alloys will be characterized at intermediate (≥10-100 /s) to high strain rates (≥1000 /s). Mechanisms that govern damage accumulation including the sequence of events that occur during strain localization and formation of ASBs will be studied. Constitutive equations and material parameters to accurately describe the properties and dynamic deformation behavior of the UFG Mg alloys will be developed.******The comprehensive experimental data, constitutive equations and predictive computational models will be invaluable in tailoring the properties of lightweight materials and form the basis for future innovative developments in lightweight technologies. In addition, this research will train highly qualified personnel with exceptional skills in material processing and characterization including electron microscopy and computational modeling currently needed by employers in the automotive and aerospace industries.

航空航天和汽车行业对通过使用镁 (Mg) 和铝 (Al) 等轻质材料来减轻重量、降低燃料消耗和温室气体排放的需求日益增长。此外，防护车辆和人员装甲需要抗冲击载荷的轻质材料，以防止受伤。镁 (Mg) 是最轻的金属，镁合金由于密度低（~1738 kg/m3，~35% < Al）而成为轻量化应用的理想选择。然而，由于其六方密排晶体结构，镁合金的成形性较差，强度适中，延展性有限。 ******超细晶粒 (UFG) 材料（晶粒尺寸 ~≤ 1000 nm）具有优于粗晶粒材料的独特的微观结构相关特性。它们是通过晶粒细化生产的，具有增强的性能，例如高强度和断裂韧性。高压扭转等剧烈塑性变形 (SPD) 技术可用于生产具有优异强度、断裂韧性和延展性的块状 UFG 镁合金。在 SPD 过程中，会对块体材料施加非常高的应变（真实应变≥1），从而导致异常的晶粒细化，而不会显着改变材料的整体尺寸。此外，还会形成大量的晶格缺陷，如晶界和位错，从而改善材料的变形行为。******本研究采用了一种协同方法，涉及 UFG 镁合金的开发和综合物理、机械和微观结构表征。将开发块状 UFG 镁合金，并研究合金中超细晶粒和晶格缺陷结构演化过程中发生的机制。还将研究晶粒细化过程中发生的机制、它们对演化微观结构的影响以及最佳加工条件。 UFG 镁合金的动态力学性能、变形行为和损伤机制将在中应变率（≥10-100 /s）到高应变率（≥1000 /s）下进行表征。将研究控制损伤累积的机制，包括应变定位和 ASB 形成期间发生的事件序列。将开发本构方程和材料参数，以准确描述UFG镁合金的性能和动态变形行为。*****综合实验数据、本构方程和预测计算模型对于定制轻质材料的性能具有不可估量的价值，并为未来轻质技术的创新发展奠定基础。此外，这项研究还将培养在材料加工和表征方面具有特殊技能的高素质人才，包括汽车和航空航天行业雇主当前所需的电子显微镜和计算建模。