Advanced Techniques for Analysis and Design in Materials Processing

加工的金属和合金有90%以上经历了凝固过程。这是与铸造和表面处理相关的许多现代实验技术和工业技术中出现的复杂过程/现象。不同的凝固条件(如过冷或冷却速度)的变化使控制晶体结构的形态和尺寸成为可能，这对合金的物理和化学性能有很大的影响。特别是，合金在低于平衡液相线和共晶处的深度过冷会导致快速凝固，并产生具有更好的机械、磁性和电学性能的材料。**铝-镁-钪合金(Al-Mg(Sc))提供了比使用Al-Mg基合金更高的强度机会。通过快速凝固使Sc过饱和的能力为研究Sc对改善Al-Mg(Sc)合金性能的作用提供了一种新的途径。这项研究将包括理论和实验两部分。**在实验中，将使用脉冲雾化(IA)-一种单液快速凝固技术-产生粉末和喷射形成的样品。Al-Mg和Al-Mg(Sc)合金都将生成。用扫描和透射电子显微镜以及X射线衍射仪、差示扫描量热仪和显微硬度对固化样品进行表征。此外，还将进行最先进的表征，如3D-微米和纳米层析成像以及中子散射。这些表征方法的目的是量化快速凝固样品中的微观偏析作为过冷的函数。利用反偏析模型，建立了初生相和共晶生长的枝晶生长速度与过冷温度(v-T)之间的唯象关系。这将与Al-Mg的经典LKT模型(固体尖锐界面生长的模型)获得的理论关系进行比较。**我们将为理解导致薄带连铸、流变铸造和喷射沉积等铸造过程中初始壳层形成的凝固结构提供基础，其中冷却速度和热流变类似于IA。我们还将首次提供一种新的方法来生成三元系统的v与deltaT关系。建议的合金系统对于加拿大在生产和制造中扮演主要角色的汽车应用非常重要。两名研究生和五名本科生将在加拿大接受培训。

Over 90% of metals and alloys processed undergo a solidification process. This is a complex process/phenomenon arising in many modern experimental techniques and industrial technologies related to casting and surfaces processing. The variation of different conditions of solidification (such as undercooling or cooling rate) gives a possibility to control the morphology and size of crystal structure, which substantially influence physical and chemical properties of alloys. In particular, deep undercooling of alloys below equilibrium liquidus, and eutectics results in rapid solidification and yields materials with improved mechanical, magnetic and electrical properties.**Aluminum-magnesium-scandium alloys (Al-Mg(Sc)) offers great opportunities for increased strength over those achieved using Al-Mg based alloys. The ability to supersaturate Sc in the alpha matrix due to undercooling through rapid solidification offers a new approach to study the effect of Sc on the improved properties of Al-Mg(Sc) alloys. This research will have both theoretical and experimental components.**Experimentally powder and spray formed samples will be generated using Impulse Atomization (IA) - a single fluid rapid solidification technique. Both Al-Mg and Al-Mg(Sc) alloys will be generated. The solidified samples will be characterized using scanning and transmission electron microscopy and by X-Ray diffraction, differential scanning calorimetry,and microhardness. In addition, state of the art characterization such as 3D-micro and nano-tomography and Neutron Scattering will be carried out. The objective of these characterization methods is to quantify microsegregation in the rapidly solidified samples as a function of undercooling. Using an inverse microsegregation model, a phenomenological relationship between dendrite growth velocity and undercooling temperature (v vs deltaT) will be developed for both primary phase and eutectic growth. This will be compared with the theoretical relationship obtained using the classical LKT model for Al-Mg (a model of the growth of the sharp interface of the solid).**We will provide a basis for understanding the solidification structure of the initial shell formation resulting in casting processes such as strip casting, rheo-casting and spray deposition where cooling rates and heat fluxes are similar to IA. We will also for the first time provide a new method to generating v vs deltaT relationships for ternary systems. The proposed alloy systems are important for automotive applications where Canada plays a major role in production and manufacturing. Two graduate students and five undergraduates will be trained in Canada.