Dresden 2006 – scientific programme

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MM: Metall- und Materialphysik

MM 17: Symposium Severe Plastic Deformation IV

MM 17.5: Fachvortrag

Tuesday, March 28, 2006, 16:30–17:00, IFW A

Thermal stability of ultrafine grained materials produced by severe plastic deformation — •Günter Gottstein, Xenia Molodova, and Myrjam Winning — Institut für Metallkunde und Metallphysik, RWTH Aachen, 52056 Aachen, Germany

Equal-channel angular pressing (ECAP) has received considerable attention recently because it provides an easy means to produce an ultrafine grain size in bulk material for improved mechanical properties.

Despite much activity in this field, information on texture evolution during heat treatment is surprisingly sparse as compared to other aspects of ECAP. Comparatively little is known about the mechanisms of microstructural change during annealing. In Copper, a nonuniform coarsening leading to a duplex microstructure was reported by several authors and usually attributed to abnormal grain growth, but equally well it can be due to discontinuous recrystallization.

We investigated microstructure and texture evolution of Aluminium and Copper based materials after ECAP deformation and subsequent heat treatment. The deformed and annealed states were characterized by crystallographic texture analysis, EBSD measurements, microhardness tests and optical microscopy. Texture formation and microstructural changes were recorded and compared to other modes of large strain deformation. The annealing phenomena were analysed with respect to recrystallization and grain growth mechanisms. Theoretical concepts were developed and will be introduced to quantitatively account for the thermal stability of severely plastically deformed metallic materials.