Dresden 2006 – wissenschaftliches Programm
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MM: Metall- und Materialphysik
MM 17: Symposium Severe Plastic Deformation IV
MM 17.4: Vortrag
Dienstag, 28. März 2006, 15:45–16:00, IFW A
Microstructural, mechanical and thermal properties of ultra-fine-grained Cu with and without dispersed nanosized Al2O3 particles — •Florian Dalla Torre1, Chris H.J Davies2, Elena V. Pereloma2, and Jörg F. Löffler1 — 1Laboratory of Metal Physics and Technology, Department of Materials, ETH Zürich, Wolfgang-Pauli-Str. 10, CH-8093 Zürich, Switzerland — 2Victorian Centre for Advanced Materials Manufacturing and Department of Materials Engineering, Monash University, VIC, 3800, Australia
Pure Cu and Cu with 0.5 wt.% nanometer-sized Al2O3 particles were processed via equal channel angular extrusion (ECAE) up to 16 and 12 passes, respectively. Microstructural analysis of both materials indicates a strong change in texture, an increase in misorientation and a reduction in subgrain and grain size between the first and the fourth pass. With a higher number of passes a more equiaxed grain structure and decreasing cell-wall thickness evolves. After 16 passes several recrystallised grains, significantly larger than the surrounding grain size and with an abundance of Sigma 3 boundaries, were detected. The tensile tests performed show an increase in plastic strain and a reduction in strength after 4-8 passes. Additional compression tests were conducted to evaluate the work hardening and the strain-rate sensitivity (SSR) as a function of number of passes. The materials show elevated SSR and work-hardening stages III, IV and V. An evaluation of the hardening contributions accounting for the Al2O3 particles indicates a linear additive behaviour in the Orowan hardening and Hall-Petch hardening for the grain-size range studied.