In this book the results of preparation and microstructure characterization of some of the polycrystalline industrial materials are reported. It is well established that "tailor made" materials with desired properties can be obtained by controlling the defect related microstructure parameters. The microstructure of a material can be characterized from an analysis of X-ray diffraction line profile that provides a nondestructive indirect method for obtaining large number of microstructure parameters. Polycrystalline materials have been prepared by vacuum melting and high energy ball milling methods. Microstructure characterization of the prepared materials has been made using X-ray powder diffraction, high- resolution optical microscopy and transmission electron microscopy etc. Mechanical property of some of the metallic alloys in terms of microhardness has been measured and structure property correlation has been established for these materials. Special emphasis has been given to the modified Warren-Averbach''s approach of Fourier analysis and Rietveld''s method of whole powder diffraction profile fitting analysis.