Theoretical and experimental studies of heat transfer phenomena will be performed involving complicated microscopic interfaces related to (1) the contact resistance problem and (2) solidification front evolution. The challenge results from there being no separation of scale between the micro- level and the averaging level, and the failure of microscopic measurement techniques in the presence of delicate microstructures. Magnetic resonance imaging (MRI) will be used for non-invasive microscopy, concentration and velocity measurements close to the solidification front, with a goal of achieving one micrometer spatial resolution and velocities down to 0.1 mm/s. For the contact resistance problem, an analytical model based upon a random distribution of finite area contact spots will be developed. MRI will also be used in this problem to identify the appropriate geometric parameters at the interface. Heat transfer problems of significance to the development of miniaturized microelectronic components, to advanced materials for the aerospace and biomedical industries, and to the further understanding of the solidification of binary alloys in metal casting will all be tackled by a unique application of MRI technology. This technique will reveal new information previously unobtainable at the micrometer level.
