Anomalous eutectics in the solidification structure of undercooled Ni–18.7 at.% Sn eutectic alloy were examined by optical metallography and electron backscattered diffraction. It was revealed that α–Ni particulates are, in principle, randomly distributed in the anomalous eutectics in the undercooling range investigated. Another eutectic phase, β–Ni3Sn, is well orientated at low undercoolings but gradually becomes inconsistent in orientation as undercooling increases, accompanied by an increasing number of grain boundaries in it. As the solidification structure changes from a mixture of anomalous eutectics plus lamellar eutectics to full anomalous eutectics beyond a critical undercooling of 130 K, however, misorientation in the β–Ni3Sn phase disappears completely from the measurement area. Partial remelting of the primary solid was proposed to be the origin of the anomalous eutectic formation, and quantitative analyses were performed.

The deformed microstructure and evolution of microstructure and texture during recrystallization of the cold-swaged multifunctional Ti-23Nb-0.7Ta-2Zr-1.2O (TNTZO, at. pct) alloy were investigated by optical microscope, electron backscatter diffraction, and transmission electron microscope. This alloy has been reported, by Saito et al., to possess a specific dislocation-free plastic deformation mechanism. In this study, the results show a curly grain or swirled structure and a pronounced fibrous 110 h i texture along the swaging axis in the cold-swaged TNTZO alloy. The normal to the swirled grain surface is near 001 h i in the cross section of the rod. This characteristic microstructure can be considered to arise from the plane strain deformation of the grains under applied stress, which is similar to that in ordinary bcc metals after heavily drawing or swaging. It is also shown that recovery involves the redistribution and partial annihilation of dislocations within the deformation bands, and recrystallization proceeds by a typical new grain nucleation-growth mechanism during annealing of the TNTZO alloy. The fibrous 110 h i deformation texture is gradually replaced by random orientations with increasing annealing time. Thus, it could be concluded that the TNTZO alloy deforms by the traditional dislocation glide on 111h i 110 f g, {112}, or {123} slip systems, rather than the dislocation-free mechanism.