Development of the next generation high strength Mg alloys for the automotive industry

几十年来，技术进步一直受到材料科学进步的推动。例如，在20世纪70年代和80年代期间，用较轻的铝部件替代汽车中的铁部件导致了立即的性能和燃料经济性的提高。最近，环境保护局和部门。美国《交通运输法》要求汽车制造商到2025年减少温室气体排放，并将燃油经济性提高50%以上，否则将面临经济处罚。人们普遍认为，这种急剧的改善是可以实现的，无论是通过车辆混合，或通过车辆重量减轻。这两种方法都面临挑战：1）混合动力成本高，增加了车辆的重量，2）现有的轻质合金制造工艺正在接近技术极限，进一步的进步成本高昂。 在这个探索计划中，我们将探索一种创新的多工艺方法，以克服与超轻高强度镁（Mg）合金现有制造方法相关的限制。具体而言，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，以开发具有与锻造镁合金相当的拉伸性能和延展性的可铸造镁合金。使用SPS，纳米和微米级陶瓷增强材料将被混合并烧结到Mg粉末基质中以形成“双相先进陶瓷改性剂”（DP-ACM）盘。随后在铸造期间将烧结的DP-ACM盘添加到液态镁合金中，导致DP-ACM的镁基质在熔体中溶解，随后在熔体中均匀释放陶瓷增强体。增强材料将用于同时提高室温强度和延展性（通过晶粒细化和共晶的改性）和抗蠕变性（通过晶界钉扎）。这种新颖的方法预计将克服几个关键的挑战（例如，颗粒沉降、浮选或氧化）。 除了制造用于处理液态镁合金的DP-ACM外，我们的小组还将研究SPS工艺参数对金属和陶瓷材料烧结性的影响。具体来说，我们的工作将集中在目前未知的影响，电流和粉末形态的粉末颗粒在SPS加工过程中的融合。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，并将为HQP提供制造和材料科学领域的实践和基础知识。该项目将为开发高强度铸造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. Recently, the Environmental Protection Agency and the Dept. of Transportation in USA mandated automakers to decrease greenhouse gas emissions and improve fuel economy by over 50% by 2025, otherwise face economic penalties. It is generally accepted that such a drastic 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 castable Mg alloys with tensile properties and ductility comparable to wrought Mg alloys. Using SPS, nano- and micro-scale ceramic reinforcements will be blended and sintered into a Mg powder matrix to form “Dual-Phase Advanced Ceramic Modifier” (DP-ACM) discs. The sintered DP-ACM discs will be subsequently added to liquid Mg alloys during casting, resulting in dissolution of the Mg matrix of the DP-ACM within the melt, followed by a homogeneous release of the ceramic reinforcements in the melt. The reinforcements will serve to simultaneously enhance the room temperature strength and ductility (via grain refinement and the modification of eutectics) and creep resistance (via grain boundary pinning). This novel approach is anticipated to overcome several critical challenges (e.g., particle settling, flotation or oxidation) associated with current treatment methods for liquid Mg alloys. In addition to fabricating the DP-ACMs for the treatment of liquid Mg alloys, our group will also investigate the effect of SPS process parameters on the sinterability of metallic and ceramic materials. Specifically, our work will focus on the presently unknown effect of the electric current and powder morphology on the fusion of powder particles during SPS processing. 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 HQPs 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.