85th Magnetic Materials Center Seminar
September 3, 2008, 9:00-
7th floor small seminar room, Sengen
Microstructural variation of Al cast alloys 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 on multilayered stacked materials of Cu-Ag and Cu-Zr processed by accumulative roll bonding was done. 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 present work microstructural variations of Al-TM (transition metal) cast alloys subjected to high pressure torsion (HPT) were investigated using SEM and TEM. The hardness of Al-2Fe and Al-2Mn alloys processed by HPT increased, and their maximum hardness values were almost the same as that of Al-3Mg subjected to HPT. The increase in hardness for the other alloys, Al-2Cr, 2Ti and 2Zr, was not evident. From TEM observations the Al-2Fe alloy showed refined-grain structure, ~50nm and finely-dispersed secondary phases.

Microstructures of as-cast and extruded Mg-6Zn-1Si-0.3Mn (ZSM610) alloy with and without Ca
C. Mendis
Recently it has been shown that the Mg-6Zn-1Si alloys show a good combination of tensile yield strength and ductility following extrusion and can be further strengthened following heat treatment. The addition of small amount of Ca results in enhancement of some tensile properties. However, the reasons behind the improved mechanical properties due to the addition of Si and Ca has not been fully understood. In this presentation microstructures observed in the cast and extruded alloys will be presented and discussed with reference to the mechanical properties observed in these alloys