METAL REFERENCE LINE TECHNIQUE FOR OBTAINING DIHEDRAL ANGLES FROM SURFACE THERMAL GROOVES

A metal reference line (MRL) technique is described for the measurement of surface–grain‐boundary dihedral angles, Ψs, from thermal grooves at a sample surface using scanning electron microscopy (SEM). Metal lines deposited onto a thermally grooved surface using photolithography conform to the contours of the grain‐boundary groove and provide a high‐contrast reference line for measuring Ψs by SEM. Measurements of Ψs from optical interferometry and calculated from groove dimensions using surface diffusion models of thermal grooving are compared with the metal reference line measurements from the same thermally grooved surface of MgO‐doped Al2O3. Distributions of Ψs are found to shift to lower angles and approach the true Ψs value as the resolution of the technique increases, with the MRL technique having the highest resolution, a median angle of 113°± 1° and a distribution of angles from 90°± 5° to 139°± 3°. Copyright © 1990, Wiley Blackwell. All rights reserved