An Sem/Ebsd Study of Shear Bands Formation in Al-0.23%wt.Zr Alloy Deformed in Plane Strain Compression / Krystalograficzne Aspekty Formowania Sie Pasm Scinania W Stopie Al-0.23%Wag.Zr Odkształcanym W Próbie Nieswobodnego Sciskania

• Published in: Archives of metallurgy and materials 2013-03, Vol.58 (1), p.145-150
• Main Authors: Paul, H., Uliasz, P., Miszczyk, M., Skuza, W., Knych, T.
• Format: Article
• Language: English
• Subjects: Crystal lattices; Crystal structure; Crystallography; Cube texture; Cubic lattice; Deformation; Diffraction patterns; Edge dislocations; Electron back scatter; Electron diffraction; FCC metals; Field emission; Grain boundaries; Grain orientation; Ingot casting; Low temperature deformation; Microstructure; Microtexture; Plane strain; Propagation; Shear bands; Slip planes; Solidification; Stacking fault energy; Substructures (crystalline); Texture; Zirconium base alloys
• ISSN: 1733-3490; 2300-1909
• DOI: 10.2478/v10172-012-0165-6

The crystal lattice rotations induced by shear bands formation have been examined in order to investigate the influence of grain boundaries on slip propagation and the resulting texture evolution. The issue was analysed on Al-0.23wt.%Zr alloy as a representative of face centered cubic metals with medium-to-high stacking fault energy. After solidification, the microstructure of the alloy was composed of flat, twin-oriented, large grains. The samples were cut-off from the as-cast ingot in such a way that the twinning planes were situated almost parallel to the compression plane. The samples were then deformed at 77K in channel-die up to strains of 0.69. To correlate the substructure with the slip patterns, the deformed specimens were examined by SEM equipped with a field emission gun and electron backscattered diffraction facilities. Microtexture measurements showed that strictly defined crystal lattice re-orientations occurred in the sample volumes situated within the area of the broad macroscopic shear bands (MSB), although the grains initially had quite different crystallographic orientations. Independently of the grain orientation, their crystal lattice rotated in such a way that one of the f111g slip planes became nearly parallel to the plane of maximum shear. This facilitates the slip propagation across the grain boundaries along the shear direction without any visible variation in the slip plane. A natural consequence of this rotation is the formation of specific MSB microtextures which facilitates slip propagation across grain boundaries. W pracy analizowano wpływ rotacji sieci krystalicznej wywołanej pojawieniem sie pasm scinania na propagacje poslizgu poprzez granice ziaren oraz na ewolucje tekstury. Badania prowadzono na próbkach stopu Al-0.23%wag.Zr, jako reprezentatywnym dla grupy metali o sredniej i duzej energii błedu ułozenia. W stanie wyjsciowym w mikrostrukturze stopu dominowały duze, silnie spłaszczone ziarna, blizniaczo wzgledem siebie zorientowane. Z odlanego wlewka wycinano próbki w ten sposób, ze płaszczyzny zblizniaczenia usytuowane były równolegle do płaszczyzny sciskania. Badania zachowania umocnieniowego analizowano w próbie nieswobodnego sciskania prowadzonej w temperaturze 77K. Próbki odkształcano do zakresu ~50% zgniotu. Analize zmian strukturalnych prowadzono w oparciu o pomiary orientacji lokalnych w SEM wyposazonym w działo o emisji polowej. Wyniki pomiarów orientacji lokalnych pokazuja, ze w obszarach zajmowanych przez makro