Segregation at Interfaces in Lightweight Alloys towards Tailored Mechanical Properties

近年来，与能源生产和运输相关的温室气体减排和燃料效率引起了人们对轻质合金开发的越来越大的兴趣。顺应这一趋势，涉及回收的可持续材料变得至关重要。镁合金是实现这一目标的主要候选者，但在常温下塑性较差，这使得加工和成形具有挑战性和成本，并阻碍了广泛的应用。了解这种含有所需和不所需溶质元素的合金的塑性机制是设计具有定制机械性能的轻质合金的必要步骤。SILA项目建议通过改进和发展能够预测溶质在晶界的偏聚及其对力学性能的影响的连续介质模型来解决这一挑战，并得到实验和原子结果的支持。力学和晶体缺陷连续介质模型的领先者梅茨的LEM3和镁合金实验表征的领导者亚琛的IMM之间独特的法德合作，提议使用原子模拟来弥合原子尺度实验和连续介质模型之间的差距。SILA将考虑含有锌或Y溶质元素的镁的双晶和三晶。原子探针层析成像的原子尺度实验表征将用于验证分离界面的分子静力学/动力学模拟。模拟的原子学细节将提供基于界面自由能过剩的新的连续介质模型，该模型能够捕捉界面上的化学-机械过程，包括晶界上当前缺陷之间的复杂相互作用。实验和数值纳米力学测试将探索镁合金的力学响应，包括与位错的相互作用，并描述界面上溶质偏析的作用。SILA旨在准确、基于实验的、连续的描述具有偏析元素的晶界，以改进应变时效合金的本构模型。这对于工程合金和回收合金来说是非常重要的，因为这些合金的界面分离溶质对机械性能有很大影响。

Greenhouse gas reductions and fuel efficiency associated with energy generation and transportation have led to increased interest in the development of lightweight alloys in recent years. Following this trend, sustainable materials involving recycling have become of crucial importance. Magnesium alloy is a major candidate to achieve this goal but suffers from poor ductility at ambient temperature, making the processing and forming challenging and costly and preventing widespread applications. Understanding the mechanisms of plasticity in such alloy containing desired and undesired solute elements is the necessary step towards the design of lightweight alloys with tailored mechanical properties.The project SILA proposes to contribute to this challenge by the improvement and development of continuum models able to predict solute segregation at grain boundaries and its impact on mechanical properties, supported by experimental and atomistic results. A unique French-German collaboration between the LEM3 in Metz, the leader in the continuum modelling of mechanics and crystalline defects, and the IMM in Aachen, the leader in the experimental characterization of Mg alloys, proposes to employ atomistic simulations to bridge the gap between atomic-scale experiments and continuum models.SILA will consider bi- and tri-crystals of Mg with Zn or Y solute elements. Atomic-scale experimental characterisation by atom probe tomography will be used to validate molecular statics/dynamics simulations of the segregated interfaces. The atomistic details of the simulations will feed novel continuum models based on the excess of interfacial free energy able to capture the chemo-mechanical processes at interfaces, including complex interactions between present defects at grain boundaries. Experimental and numerical nano-mechanical tests will explore the mechanical response of the Mg alloys, including the interaction with dislocations, and describe the role of solute segregation at interfaces.SILA aims at an accurate, experiment-based, continuum description of grain boundaries with segregated elements, to improve constitutive models for strain-aged alloys. This is of prime importance for engineering alloys and recycled alloys whose segregated solutes at interfaces impact largely mechanical properties.