MICROSTRUCTURAL MODELS FOR QUANTITATIVE-ANALYSIS OF GRAINS AND 2ND-PHASE PARTICLES

Microstructural models for quantitative analysis of shapes and orienta tions of grains and second-phase particles on plane sections have been proposed. The models use rectangle, ellipse, regular, and elongated p olygons as idealized shapes. For each shape, a function describing the change of average linear intercept length with the scan angle has bee n derived. These functions are used in the identification of individua l shapes as well as in the quantitative characterization of the collec tion of two-dimensional objects such as grains and particles. In addit ion, the shape index proposed in the authors' earlier work has now bee n extended to describe the conglomerates of grains or second phase par ticles. A new orientation factor describing an object's alignment has also been proposed. A simple method for constructing the normalized av erage intercept length versus scan angle plots using polar coordinates is also presented. The utility of the proposed methodology is illustr ated in an example of the characterization of the size, shape, and deg ree of orientation of subgrains in the 7050 aluminum alloy.