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.

对航空航天和汽车行业的需求越来越不断增加，以减少体重，燃油消耗和通过使用轻质材料（例如镁（MG）和铝（AL））的温室气体排放。同样，在受保护的车辆和人员装甲中需要抵抗冲击负荷的轻质材料以防止受伤。镁（mg）是最轻的金属，由于其低密度（〜1738 kg/m3，〜35％<al），因此需要用于轻质应用。然而，由于六角形闭合晶体结构，MG合金暴露了差的形成性，中等强度和有限的延展性。 *****超铁颗粒（UFG）材料（粒度〜≤1000 nm）具有独特的微结构依赖性特性，优于粗粒材料。它们是通过谷物细化产生的，具有增强的特性，例如高强度和断裂韧性。严重的塑性变形（SPD）技术（例如高压扭转）可用于生产具有特殊强度，断裂韧性和延展性的大量UFG MG合金。在SPD期间，非常高应变（真正的应变≥1）被施加在散装材料上，从而导致特殊的晶粒细化，而没有明显改变材料的整体尺寸。同样，形成了大量的晶格缺陷，例如晶界和位错，以改善材料的变形行为。将开发大量的UFG MG合金，并在合金中超铁颗粒和晶格缺陷结构演变过程中发生的机制进行研究。在晶粒细化过程中发生的机制，它们对进化的微观结构和最佳加工条件的影响也将是研究的。在中间体（≥10-100 /s）的高应变率（≥1000 /s）时，将对UFG MG合金的动态机械性能，变形行为和损伤的机制进行表征。控制损伤加速度的机制将研究在应变定位和ASB的形成过程中发生的事件序列。将开发构造方程和材料参数，以准确描述UFG MG合金的性能和动态变形行为。此外，这项研究将培训具有材料处理和特征方面具有卓越技能的高素质人员，包括电子显微镜和汽车和航空航天行业中雇主当前所需的计算建模。