THE DETERMINATION OF LOW-ENERGY GRAIN-BOUNDARIES BY THE SPHERES-ON-PLATE EXPERIMENT IN CU AND CU-0.1 AT-PERCENT MN

Low-energy grain boundaries in pure Cu and a Cu-0.1 at% Mn alloy are d etermined by sintering small single crystalline spheres on single crys talline plates. The plates are {100}- and {111}-oriented. Spheres and plates are of the same material. Contrary to previous experiments the specimens are investigated by means of a scanning electron microscope (SEM). For each sphere the shape of the sintering neck and the positio n of the grain boundary in the sintering neck is determined. Additiona l measurements of the sphere orientations in the SEM allow accurate de terminations of the orientation relationships between spheres and plat es. Orientation relationships near the coincidence relations Sigma 3, Sigma 9, Sigma 11, Sigma 17b, and Sigma 33c occur preferentially. The observed deviations from the ideal coincidence relations are significa nt. The majority of the grain boundaries can be characterized as asymm etrical tilt-twist boundaries. For each orientation relationship alway s one type of interface and hence one grain boundary character is pref erred. Additionally, the distributions of the orientation relationship s are influenced by the plate orientation.