Grain Size Estimation in Anisotropic Materials

摘要

The estimators proportional to (N_A(x,y)N_A{x,z}N_A(y,z))~(1/2) and (N_L(x)N_L(y)N_L(z)) obtained by profile and intercept counts are recommended by ASTM Standards E 112 for 3D grain intensity lambda of anisotropic grain structures (N_A(centre dot) are estimated in three mutually perpendicular planes suitably oriented with respect to the prevailing anisotropy direction and N_L(centre dot ) are intercept intensities along three suitably selected mutually perpendicular directions). However, X is also related to the profile and intercept intensities X', X", namely X= c'(lambda')~(3/2)= c"(?v")3. The induced intensities are estimated by arithmetic means N_A = {N_A(x,y)+N_A(x,z)+N_A(y,z)y3, N_L = (N_L(x)+N_L(y)+N_L(z))/3. A simple model is developed, in which the role of geometric and arithmetic means of profile and intercept counts in the grain size estimation is elucidated. Its results are compared with computer simulated random tessellations with prevailing rod-like and plate-like cells and applied to anisotropic grain structures of pure Al produced by ECAP and to platinum based composite Pt - 0.5 Y2O3.