Quantitative Characterization of Spatial Arrangement of Microstructural Features in Metal Matrix Composites

摘要

Spatial arrangement of microstructural features (particles, voids, grains, etc) is an important facet of microstructural geometry that affects the fracture sensitive properties (ductility, strength, fatigue life, etc) of monolithic as well as composite materials. Nonetheless, the experimental technique for quantitative characterization of the important descriptors of the spatial arrangement of microstructural features are not well developed. Such quantitative information is necessary to understand how parameters such as spatial clustering affect the fracture sensitive mechanical properties. The central objective of the research program was to develop general and flexible experimental techniques for quantitative characterization of spatial arrangement of features in material microstructures, and application of these techniques to quantify clustering and microstructural non-uniformities in the three-dimensional (3D) microstructures of discontinuously reinforced metal matrix composites. The research program involved reconstruction of 3D microstructures of discontinuously reinforced al-alloy matrix composites from montage serial sections and detailed characterization of the 3D microstructural geometry. The research led to development of stereology and digital image analysis based technique for efficient estimation of two-point correlation functions in 3D microstructures. These correlation functions were then utilized for computer simulations of the 'realistic' microstructures that are statistically similar to the corresponding real microstructures. The research program also led to the development of some fundamental theoretical results concerning the nearest neighbor distribution functions and higher order correlation functions.