A multi-process approach towards the development of novel Mg alloys

几十年来，材料科学的进步推动了技术的进步。例如，在20世纪70年代和80年代，用较轻的铝部件代替汽车中的铁部件，立即提高了汽车的性能和燃油经济性。鉴于全球气候变化的挑战，各国政府都要求汽车制造商大幅减少温室气体排放，提高汽车的燃油经济性，否则将面临经济处罚。人们普遍认为，所需的改进可以通过车辆混合动力或车辆减重来实现。这两种方法都面临着挑战：1)杂交技术成本高，而且会增加车辆的重量；2)现有的轻质合金制造工艺正接近技术极限，进一步发展成本高昂。在这个探索项目中，我们将探索一种创新的多工艺方法，以克服与现有超轻高强度镁合金制造方法相关的限制。具体来说，先进的粉末冶金工艺（火花等离子烧结，SPS）将与传统的金属铸造工艺相结合，开发出含有石墨烯基添加剂的新型镁合金复合材料。一个关键的目标是开发适合批量生产的复合材料，同时保持成本效益。使用SPS，石墨烯基添加剂（如石墨烯，氧化石墨烯或还原氧化石墨烯）将与Mg粉末结合并烧结形成母合金。烧结后的母合金随后在铸造过程中被添加到液态镁合金中，导致Mg母合金在熔体中溶解，随后在熔体中释放石墨烯基添加剂。添加剂将同时提高合金的强度和延展性（通过晶粒细化和共晶改性）和热电性能。使用这种方法，与当前液态镁合金处理方法相关的几个关键挑战（例如，颗粒沉降、浮选或氧化）将被超越。此外，这种新型复合合金将特别适合下一代混合动力/电动汽车的应用。除了开发用于批量生产Mg零件的新型合金外，我们的团队还将研究SPS工艺参数和粉末形貌对主合金烧结性能的影响以及它们与石墨烯基添加剂的相互作用。所产生的知识将使烧结材料具有精确控制的微观结构和性能。这两个领域的实验工作将在我的UBC实验室进行，并将提供HQP在制造和材料科学领域的实践和基础知识。该项目将为开发可浇注高强度镁合金的新方法奠定基础。

For decades, technological advancements have been driven by the progress in materials science. For example, the substitution of iron components in automobiles with lighter aluminum components during the 1970's and 80's resulted in an immediate performance and fuel economy enhancement. In light of the global climatic challenges, governments internationally are mandating automakers to drastically decrease greenhouse gas emissions and improve fuel economy of vehicles, otherwise face economic penalties. It is generally accepted that the required improvement is achievable either by vehicle hybridization, or by vehicle weight reduction. Both approaches face challenges: 1) Hybridization is costly and adds weight to vehicles, and 2) Existing manufacturing processes for lightweight alloys are approaching technological limits and further advancements are costly.     In this Discovery program, we will explore an innovative multi-process approach to overcome the limits associated with existing manufacturing methods for ultralight high-strength magnesium (Mg) alloys. Specifically, an advanced powder metallurgy process (Spark Plasma Sintering, SPS) will be combined with a traditional metalcasting process to develop novel Mg alloy composites containing graphene-based additives. A critical goal will be to develop composites suitable for mass production, yet remaining cost efficient. Using SPS, graphene-based additives (e.g., graphene, graphene oxide or reduced graphene oxide) will be combined with Mg powder and sintered to form a master alloy. The sintered master alloy will be then subsequently added to liquid Mg alloys during casting operations, resulting in the dissolution of the Mg master alloy within the melt, followed by the release of the graphene-based additives in the melt. The additives will serve to simultaneously enhance the strength and ductility (via grain refinement and the modification of eutectics) and thermo-electric properties of the alloys. Using this approach, several critical challenges (e.g., particle settling, flotation or oxidation) associated with current treatment methods for liquid Mg alloys will be surpassed. Further, the novel composite alloys will be particularly tailored towards applications in the next-generation of hybrid / electric vehicles.     In addition to developing novel alloys for mass-produced Mg parts, our group will also investigate the effect of SPS process parameters and powder morphology on the sinterability of the master alloys and their interaction with the graphene-based additives. The generated knowledge will enable sintering of materials with precisely controlled microstructure and properties.     Experimental work in both areas will be carried out at my UBC laboratories and will provide HQP hands-on and fundamental knowledge in the fields of manufacturing and materials science. This program will provide a foundation for a novel approach to develop castable high-strength Mg alloys.