Quantitative Description of the Evolution in the Geometry of Grains in a Pure α-Fe

Abstract
Grains in polycrystals differ in their size and shape. The geometry of grains in a given polycrystal is described by the distribution functions of grain size and shape. These functions can be experimentally studied using the methods of quantitative stereology and image analysis. The geometry of grains is related to the physical properties of the grain boundaries and vice versa. The distribution function of the geometrical features of grains can help in the assessment of the physical properties of the grain boundaries. Distribution functions of grains size and shape were investigated in an UHP iron produced at EMSE and in a commercially available Armco iron. Populations of grains in the specimens studied were characterized in terms of mean grain volume, E(V), grain section area, E(A) and the grain size diversity ratio. The data obtained in the study provide a quantitative description of the evolution in the geometry of grains during recrystallization and grain growth. It was found that there are systematic differences in the geometrical features of grains in UHP iron and Armco iron. The possible contribution of these differences to the disparity in the properties of the UHP materials is discussed.