Upcycling of Light Alloy by Rheoforming Scrap (ULARS)

与其他用于工程应用的材料不同，金属，如铝和镁，可以重复回收，而不会损失其固有性能。回收金属不仅在经济上是可行的，而且对保护有限的自然资源、减少能源消耗和产生废物也非常有益，所有这些都对可持续经济做出了积极贡献。增加使用回收轻合金废料(包括工艺废料(新的)和消费后的废料(旧的))的主要障碍之一是夹杂物和杂质元素含量过高，这通常会导致材料降级为机械性能较差和耐蚀性降低的材料。拟议项目的主要目标是通过应用阶梯变化流变成形技术打破这一障碍，防止市场失灵，使铝和镁合金废料能够在高级汽车和其他附加值应用中重新使用。技术方法是使用双螺杆浆料成型机(TSSM)和浆料蓄积器相结合，将回收的轻合金废料熔体转化为半固态浆料，并将其送入流变式铸造机，以获得近净形状的部件，或送入流变式挤出机，用于连续挤压型材。由于TSSM中强烈的强迫对流，夹杂物和杂质元素(通常是凝固组织中的金属间化合物)都将被分成极细的颗粒，均匀分布在整个铸造过程中，消除/减少了对塑性和耐腐蚀性的不利影响。这将导致材料的广泛再利用，生产铝和镁合金的铸件和挤压型材，这些铸件和挤压型材是由Norton铝业提供的消费后废料(PCS)和子午线提供的镁压铸废料的精选组合制成的。将根据目前生产的铝和镁铸件以及由传统初级金属熔体制成的锻造产品来评估变型产品的机械性能和腐蚀性能。对于镁来说，该项目的重点将是生产流变压铸件，而锻造产品的生产活动要小得多，而对于铝来说，重点将同时放在高性能铸件和锻造产品上，特别是流变挤压件。BCAST的工作将集中在以下几个方面：(1)作为技术提供商，BCAST团队将专注于开发流变成形技术，特别是流变压铸和流变挤出工艺，将轻合金废料升级为汽车和其他一般工程应用的高质量部件。这将包括流变挤出机的设计、调试和优化，以及流变挤出机与浆料供应系统的集成。(2)BCAST小组将对由不同废料来源生产的流变成形产品的化学成分、微观结构、机械性能和耐腐蚀性进行表征。结果将作为指导方针输入到工艺优化计划中，并将用于了解化学成分、工艺条件和工程性能之间的关系。(3)BCAST团队将协助诺顿铝业公司铝废料的流变成形和子午线的镁废料流变压铸的工业规模试验。该项目将在英国建立独特的材料生产商、回收商、技术提供商和产品制造商合作伙伴关系，开发一条新的加工路线，通过升级到更高价值的产品来增加轻合金材料的再利用和回收含量。这种合作开发将使英国能够快速进行商业开发，并将减少对进口产品的依赖。

Summary Unlike other materials for engineering applications, metals, such as aluminium and magnesium, can be recycled repeatedly without loss of their inherent properties. Recycling metals is not only economically viable, but also extremely beneficial for conservation of limited natural resources, reduction of energy consumption and waste generation, all contributing positively to a sustainable economy. One of the main barriers to the increased use of recycled light alloy scrap (both process scrap (new) and post consumer scrap (old)) is the existence of excessive levels of inclusions and impurity elements, which usually leads to downgrading into materials with poorer mechanical properties and reduced corrosion resistance. The prime objective of the proposed project is to break down this barrier and prevent market failure through the application of the step-change rheoforming technologies to allow the re-use of aluminium and magnesium alloy scrap in high-level automotive and other value added applications. The technical approach is to convert melts of recycled light alloy scrap into a semi-solid slurry using a twin screw slurry maker (TSSM) combined with a slurry accumulator and to feed this into a rheodiecaster for near net shape components, or a rheoextruder for continuous extruded profiles. Owing to the intensive forced convection in the TSSM, both inclusions and impurity elements (usually as intermetallic compounds in the solidified microstructure) will be divided into extremely fine particles and dispersed uniformly throughout the entire casting, eliminating/reducing the detrimental effects to ductility and corrosion resistance. This will result in extensive materials re-use, producing castings and extruded sections of aluminium and magnesium alloys made from selected combinations of post consumer scrap (PCS) supplied by Norton Aluminium and magnesium diecasting scrap supplied by Meridian. The mechanical performance and corrosion properties of the rheoformed products will be assessed against current production aluminium and magnesium castings and wrought products made from conventional primary metal based melts. For magnesium the emphasis of the project will be on production of rheodiecastings with a much smaller activity on wrought products, whilst for aluminium the emphasis will be both on high performance castings and on wrought products, particularly rheoextrusions. The work at BCAST will focus on the following aspects: (1) As the technology provider, BCAST team will focus on developing the rheoforming technologies, particularly the rheo-diecasting and the rheoextrusion processes, for upcycling light alloy scrap into high quality components for automotive and other general engineering applications. This will include design, commissioning and optimisation of the rheoextruder, integration of the rheoextruder with the slurry supply system. (2) The BCAST team will characterise the chemical compositions, microstructures, mechanical properties and corrosion resistance of rheoformed products produced from different scrap sources. The results will feed into the process optimisation programme as guidelines, and will also be used to understand the relationships between chemical composition, processing conditions and engineering performance. (3) The BCAST team will assist the industrial scale trials for rheoforming Al scrap at Norton Aluminium and for rheo-diecasting of magnesium scrap at Meridian. The project will develop a unique UK partnership of material producers, recyclers, technology providers and product manufacturers to develop a novel processing route for increasing the re-use and recycled content of light alloy materials by upcycling into higher-value products. Such a collaborative development will enable rapid UK commercial exploitation and will reduce dependency on imported products.