Advanced Techniques for Analysis and Design in Materials Processing

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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.