The dihedral angle shown by intergranular lead inclusions in Cu–1wt%Pb alloys was measured varying the purity of the metal and the temperature. Several measurement methods were used and compared, namely classical 2-dimensional methods based upon metallurgical cross-section analysis and a recently developed 3-dimensional stereoscopic method that yields the true three-dimensional angle value for individual inclusions straddling a flat grain boundary. Earlier measurements were confirmed and extended by using the new method. It was shown that a discrepancy, found between literature data and the stereoscopic 3-dimensional dihedral angle measurements, was not caused by impurity effects. Rather, the data indicated that the discrepancy had its origin in a difference in average dihedral angle values measured between inclusions straddling two grains and values found at inclusions located where three or more grains met.

Dihedral Angles in Cu–1wt%Pb - Grain Boundary Energy and Grain Boundary Triple Line Effects. D.Empl, L.Felberbaum, V.Laporte, D.Chatain, A.Mortensen: Acta Materialia, 2009, 57[8], 2527-37