Structure-property relationships in engineering materials is the broad area of interest of the P.I. Current work falls into three categories: solidification processing of alloys and metal-matrix composites, toughening mechanisms in nonferrous alloys and ceramic composites, and the study of the structural changes in friction materials. Analytical work in the area of solidification processing has focused on the two dimensional simulation of the phenomenon of microsegregation in alloy castings. Finite element and finite difference techniques are employed to investigate transient temperature and composition profiles and to determine the interface morphology for alloys and pure metals, including natural convection effects, the heat storage effect in the mold media, and the dissipation of the surface wave during mold filling. The algorithms, developed from first principles of mass, momentum and energy, yield results which agree well with those reported in the literature. Future plans in this area involve the extension of this work to three dimensions and the placement of reinforcing fibers in the mushy zone of the alloy during the solidification simulation. Combined analytical and experimental techniques are employed to study the deformation and toughening mechanism in ceramic matrix composites. The results of the limited experimental investigations are used in the two dimensional finite element model of the crack intersecting a single fiber in the composite. In the third category during the application of friction, the materials experience local hot spots which themselves cause changes in the structure of the materials. The characterization of these changes and their effect on the production of noise during braking are being studied using semimet materials.
