It was noted that the {101} transformation twinning bands in Mn-Cu alloys were considered to be the dominant microstructural feature which contributed to the high damping capacity of the alloys. Because the face-centred-tetragonal phase of Mn-Cu alloys had an axial ratio, c/a, of nearly unity, an angular resolution - for Kikuchi diffraction bands - of better than 0.5° was necessary in order to identify twin boundaries by using the electron back-scattering diffraction method. At some angular resolutions, [100] and [001] orientations of the face-centered-tetragonal phase could be randomly recorded within the single twinning band. In contrast, the image-quality signal of electron back-scattering diffraction contained a reflection that was sensitive to the twinning bands. The image-quality contrast was produced by the average orientation difference between the twinning bands. Therefore, the twinning bands of Mn–Cu alloys could be identified by partitioning the orientation distribution of the normal direction for the observed sample section in a range of about 1°. With the aid of a {101} stereographic projection, the width of the twinning bands and the intersection morphology were analyzed for a Mn–Cu alloy. The observed intersection morphology was related to a 60° or 90° spatial intersection configuration of different groups of twinning bands. In addition, the sharpened ends of twinning bands at the junction regions, and secondary twinning phenomena, were also characterized.

EBSD Characterization of the Twinning Microstructure in a High-Damping Mn–Cu Alloy. F.Yin, T.Sakaguchi, Y.Zhong, A.Sakurai, K.Nagai: Materials Transactions, 2007, 48[8], 2049-55