Some aspects of solidification: solute transport in the generation of microstructure

本申请人的大部分研究生涯都与凝固的科学和实践有关，即如何帮助用户制造更好的铸件。 用于铸造产品的金属通常是由一种丰富的元素（溶剂）和少量其他元素（溶质）组成的合金。 当液态金属开始凝固时，溶质往往会集中在铸件的小区域内，并有助于产生铸造金属的“微观结构”，这对确定铸态性能很重要。 经验知识不再足以满足当前对更高质量的表面光洁度和/或更坚固的产品的需求，因此这导致了铸造过程的“数字建模”，即铸造工程师对铸造过程本身以及（比如）液态金属在倒入模具中时的温度将影响最终的微观结构并因此影响铸造材料的最终性能。 定制模型的开发通常是大型工业铸造工艺的设计和操作的必要组成部分，如果它要在经济上与他人竞争的话。 然而，任何计算机模型都只能与建模者使用的物理和化学数据的准确性一样好。 由于要铸造的金属含有溶质，并且溶质在合金凝固期间四处移动-“扩散”，因此必须获得主要溶质的准确扩散速率。 由于这一领域的许多已公布的数据不是特别准确，本提案的主要目的是寻求更好地了解这种扩散速率如何随温度变化。关于对人力资源合格人员的培训，该项目涉及发展计算技能和物理测量的精确性-这两项在加拿大工作场所都非常重要。

Much of this applicant's research career has been concerned with the science and practice of solidification i.e. how to help the user to make better castings. The metal used for cast products is usually an alloy consisting of one element in abundance (the solvent) and smaller percentages of a number of other elements (solutes). When the liquid metal begins to solidify, the solutes tend to become localised in small regions of the casting and help to produce the 'microstructure' of the cast metal, important in determining the as-cast properties. Empirical knowledge is no longer sufficient to meet the current demand for a higher quality in surface finish and/or stronger products and so this has resulted in the casting process being 'numerically modeled', i.e. casting engineers develop a detailed understanding of the casting process itself and how small changes in (say) the temperature of the liquid metal when poured into the mold will affect the final microstructure and hence the final properties of the cast material. The development of a custom-built model is usually an imperative component of the design and operation of the larger scale industrial casting process if it is to be economically competitive with others. However, any computer model will only be as good as the accuracy of the physical and chemical data used by the modelers. Since the metal to be cast contains solute and that solute moves about - 'diffuses' - during the freezing of the alloy, it is imperative that accurate diffusion rates for the principal solutes be available. Since much of the published data in this area is not particularly accurate, the major aim of this proposal is to seek a better understanding of how such diffusion rates change with temperature. With respect to the training of HQP, the project involves the development of computational skills and precision with physical measurements - both of great importance in the Canadian workplace.