75th Magnetic Materials Center Seminar
May 15, 2008, 9:00-
7th floor small seminar room, Sengen

B. S. Rao


Microstructural variation of two phase materials processed by high pressure torsion
K. Oishi
Severe plastic deformation (SPD) has been known as a technique to provide ultrafine grained and nano-grained structure. When the SPD is applied to two phase alloys, the dissolution of precipitates and the formation of supersaturated solid solution occur. In our group microstructure characterization has been done on multilayered stacked materials of Cu-Ag and Cu-Zr processed by accumulative roll bonding (ARB). The study showed that a supersaturated solid solution forms in the Cu-Ag material, while amorphization occurs in the fine Zr layer in the Cu-Zr material. In preset work microstructural variations of Al/Cu two-phase materials subjected to high pressure torsion (HPT) were investigated using SEM and TEM. After 10 turns of HPT, banded structure was observed near the edge of the disk. But at the center region of the disk the regions of Al and Cu phases as well as their boundaries were clear. After 100 turns of HPT, fine and irregularly distorted banded structure of Al and Cu are apparent throughout the specimen. TEM observations show that Al2Cu-phase particles form at the grain boundaries of Al and along the Al-phase layers.