Microstructure Mechanisms Governing the Creep Life of Ultrafine-grained Cu-0.2wt.%Zr Alloy

0367034 - ÚFM 2012 RIV CZ eng A - Abstrakt
Král, Petr - Svoboda, Milan - Dvořák, Jiří - Kvapilová, Marie - Sklenička, Václav
Microstructure Mechanisms Governing the Creep Life of Ultrafine-grained Cu-0.2wt.%Zr Alloy.
12th International Symposium on Physics of Materials. Roč. 12, č. 12 (2011), od 72 do 72
[12th International Symposium on Physics of Materials. 04.09.2011-08.09.2011, Praha]
Grant CEP: GA ČR(CZ) GAP108/11/2260
Výzkumný záměr: CEZ:AV0Z20410507
Klíčová slova: ultrafine-grained materials * creep * copper alloy
Kód oboru RIV: JJ - Ostatní materiály

Equal-channel angular pressing (ECAP) was conducted at room temperature and extrusion passes were processed by route Bc up to 12 passes. Tensile creep tests were performed at 473 K, 573 K and 673 K at different constant applied stresses. It was observed that the original coarse grain size of unprocessed alloy was reduced to 0.3 µm after 8 ECAP passes and the grain growth during creep was restricted by precipitates with the mean diameter ~ 4.0 nm. No significant effect on creep resistance was found after one ECAP pass at 473 and 573 K. However, the longest time to fracture was exhibited by alloy after 2 ECAP passes at 573 and 673 K but with further increasing number of ECAP passes a decrease in the time to fracture was observed. Nevertheless, the beneficial effect of ECAP on creep resistance was still documented after 8 passes for temperatures of 473 and 573 K. By contrast, creep tests performed at 673 K showed that the time to fracture of UFG material is shorter as compared with that for as-received state. The 3 D laser measurement of surface showed that the creep fracture process is accelerated by formation of vertical surface step relief and cavitation at the intersection of the shear bands during creep.
Trvalý link: http://hdl.handle.net/11104/0201828