Dispersion Strengthened Magnesium Alloys - Solidification of Nanocolloids

车辆轻量化是国家交通运输脱碳综合方法的重要组成部分。人们普遍认为，到2050年，汽车的二氧化碳排放量需要减少至少50%，以防止全球汽车从油井到车轮的碳排放量超过70亿吨，而不是更可持续的40亿吨。英国政府制定了更高的目标，即到2030年将交通部门的二氧化碳排放量减少60%。在所有类别的车辆中实施轻量化对实现这一目标起着重要作用。镁（Mg）作为一种最轻的结构金属，具有优异的阻尼能力，在实现车辆轻量化方面具有巨大的潜力，同时改善了噪音、振动和恶劣性能。最近的Mg市场研究表明，全球Mg合金市场将从2018年的10亿英镑增加到2026年的28亿英镑，2019年至2026年的复合年增长率约为12.7%，预计这将受到汽车和运输应用对Mg合金的需求的推动，因为燃油效率和排放法规。汽车行业的目标是到2030年将镁含量从2017年的8.6公斤/辆提高到45公斤/辆。在各种镁合金中，含铝镁合金因其具有成本优势而被广泛应用于汽车领域。然而，由于其强度较低，阻碍了其在汽车上的广泛应用。为了帮助实现这一增长并满足严格的轻量化设计和安全标准，有必要显著提高现有具有成本效益的Mg-Al合金的强度。在镁中加入稀土元素和贵金属已成功地实现了强度的显著提高。具有高稀土含量的合金表现出更高的强度，满足轻量化设计要求。然而，稀土元素合金由于资源稀缺和成本高，难以在汽车领域大规模应用。如果非原位相颗粒分散在Mg基体内而不是在晶界处偏析，则可以发挥析出硬化的作用。通过概念验证研究，提出的研究计划旨在开发高强度，具有成本效益的分散强化镁（DSM）合金。它还研究了纳米胶体稳定性的标准，凝固行为，并建立了适用于使用实际铸造工艺制造DSM合金的工艺图。从技术上讲，帝斯曼合金代表了轻量化汽车零部件制造技术的重大变革。如果某些铝和钢被DSM合金取代，预期的重量减轻将是显著的。从长远来看，它将显著减少二氧化碳排放，并节省大量燃料。由材料供应商、零部件生产商、合金设计师和最终用户组成的工业合作伙伴是一种附加价值，有助于加速从学术界到工业的知识转移活动。

Vehicle lightweighting represents a vital strand of an integrated national approach to transport decarbonisation. There is a general agreement that the CO2 emissions from cars needs to be cut by at least 50% to prevent the well-to-wheels carbon emission from the world car fleet rising above 7bn tonnes rather than the more sustainable 4bn tonnes by 2050. The UK Government has set an even higher target of a 60% reduction in transport sector CO2 emissions by 2030. Implementation of lightweighting across all classes of vehicles plays an important role in achieving this target.Magnesium (Mg), as a lightest structural metal combined with superior damping capacity, has tremendous potential in achieving lightweighting in vehicles with improved noise, vibration and harshness performance. Recent Mg market research suggests that the global Mg alloys market will increase from £1 billion in 2018 to £2.8 billion by 2026, at a CAGR of ~12.7% between 2019 and 2026 which is expected to be driven by demand for Mg alloys from the automotive & transportation applications due to fuel efficiency and emission regulations. The automotive industry is aiming to increase Mg content from 8.6kg/car in 2017 to 45kg/car by 2030. Among variety of Mg alloys, aluminium containing Mg (Mg-Al) alloys are being used in automotive sector due to their competitive cost. However, their widespread use in vehicle is hindered by their lower strength. To help realise this growth and to meet the stringent design and safety criteria for lightweighting, it is necessary to enhance the strength of existing cost-effective Mg-Al alloys significantly. The addition of rare-earth (RE) elements and noble metals in magnesium has been successfully utilised to achieve a significant improvement in strength. The alloys that have high RE content exhibit improved strength that meets lightweight design requirement. However, due to the resource scarcity and high cost, the alloys containing RE elements are impractical for their mass structural applications in automotive sector. The role of precipitation hardening in Mg alloys could be fulfilled by ex-situ phase particles, if they are dispersed within the Mg matrix rather than segregated at the grain boundaries. Substantiated by the proof-of-concept study, the proposed research programme aims to develop high strength, cost effective dispersion strengthened magnesium (DSM) alloys. It also investigates the criteria for the stability of nanocolloids, solidification behaviour and establishes process maps suitable for manufacturing DSM alloys using practical casting processes. Technologically, the DSM alloys represent a step change in the manufacturing technology to produce lightweight automotive components. If certain Al and steel are replaced with DSM alloys, the expected weight saving would be significant. In the longer term, it will lead to a significant reduction in CO2 emissions and offer sizable fuel savings. The industrial partners, comprising a materials supplier, component producers, alloy designer and an end user are an added value and help to accelerate the knowledge transfer activity from academia to industry.