Papers by Author: Seiichiro Ii

Abstract: Grain boundary structures in the commercial purity aluminum (1100Al) highly deformed by the accumulative roll bonding (ARB) process was observed by using conventional transmission electron microscopy (CTEM) and high resolution transmission electron microscopy (HRTEM). In the low angle grain boundary with a tilt angle (2θ) of 2.1o consisted of the periodic dislocations array, the interval of those dislocations could be explained by the dislocation model for grain boundary. However, the dense dislocation region locally existed at the vicinity of the low angle boundary. On the other hand, we also observed the high angle grain boundary of which the common axis and 2θ was <110> and 125.9o, respectively. In this grain boundary, we could describe the boundary configuration in terms of the combination of the kite-shaped structure unit characterized by Σ11 coincidence boundary with the 2θ of 129.52o around <110> and the additional dislocations to compensate the difference of the actual and geometrically coincided one.

Abstract: In the research center for advances in impact engineering established in Sojo university, advanced materials have been synthesized by using shock wave and their microstructure has been investigated. An extremely high shock pressure and a dynamic hot compaction technique were developed, and the synthesis of the advanced materials and composites was succeeded. Transmission electron microscopy observations revealed unique microstructures of such materials obtained by our original advanced technique.

Abstract: Interfacial microstructure of TiN-TiB2 composite, which was synthesized by hot shock compaction combined explosively shock condolidation and self-propagating high-temperature synthesis, was investigated by transmission electron microscopy (TEM). In the TiN-TiB2 composite included 60mol% TiN, an experimentally measured average grain size of the both TiN and TiB2 was approximately 500nm, and it decreased rather than those of the raw powders. By the conventional TEM observations, we clarified that there was a specific orientation relationship between cubic TiN and hexagonal TiB2. The high resolution electron microscopy (HREM) observations revealed that the TiN/TiB2 interphase boudnaries were atomically flat. We also observed grain boundaries of the composite and found that no secondary phases such as amorphous phase and precipitates were observed at the grain boundaries in the composite.