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

这位申请者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一种合金，由一种丰富的元素(溶剂)和少量其他元素(溶质)组成。当液态金属开始凝固时，溶质倾向于在铸件的小区域内定域，并有助于产生铸件的“微结构”，这对决定铸件的性能很重要。经验知识已经不足以满足当前对表面光洁度和/或更坚固产品的更高质量的需求，因此这导致了铸造过程被‘数值模拟’，即铸造工程师开发了对铸造过程本身的详细了解，以及当浇注到模具中时液态金属的温度的微小变化如何影响最终的微结构，从而影响铸造材料的最终性能。如果要在经济上与其他工艺竞争，定制模型的开发通常是较大规模工业铸造工艺设计和运行的必要组成部分。然而，任何计算机模型都将取决于建模者使用的物理和化学数据的准确性。由于要浇铸的金属含有溶质，而且在合金凝固过程中，溶质四处扩散，因此必须获得主要溶质的准确扩散速率。由于这一领域公布的许多数据不是特别准确，这项提议的主要目的是寻求更好地了解这种扩散速度如何随温度变化。关于HQP的培训，该项目涉及发展计算技能和物理测量的精确度--这两项在加拿大的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.