Accumulative roll bonding (ARB) allows producing ultrafine-grained sheets of high strength and has been successfully used to prepare such materials from aluminium alloys. However, due to intensive work hardening of bond-rolled AlMg3 sheets, significant edge cracking occurred. Cracking was reduced by cladding AlMg3 with aluminium. Lamellar composites were thus prepared. Their structure was studied by electron backscatter diffraction and transmission electron microscopy; hardening was evaluated by microhardness measurements and tensile tests. Composite grain sizes are coarser than in the mono-material sheets. Accordingly, the evolution of strength with ARB-cycling in both materials differs. AlMg3 composite layers exhibit less work hardening than the mono-material; the composite strength is between that of the two mono-material ARB-sheets while the ductility does not differ substantially.

The influence of plastic deformation and heat-treatment on the precipitation of Al3(Sc, Zr) particles and the effect of these precipitates on hardening and softening processes of dilute ternary Al-0.2wt.%Sc-0.1wt.%Zr alloy was investigated. Behaviour of two differently prepared alloys (mold cast and prepared by powder metallurgy – PM) was investigated in as-prepared and in cold rolled state. Both alloys exhibit the same peak age hardening, PM one reaches it already during extrusion at 350°C. Both cold rolled alloys are highly resistant against recovery, which proceeds without rapid hardness decrease at high temperatures. Evolution of hardness agrees well with that of resistivity and with TEM observation.

EBSD investigation of the grain boundary distributions in ultrafine-grained Cu and Cu-Zr polycrystals prepared by equal-channel angular pressing Ultrafine-grained copper and cooper-zirconium polycrystals prepared by equal-channel angular pressing following the route Bc to various strain (1, 2, 4 and 8 passes) were investigated using electron back-scatter diffraction. Equalchannel angular pressing resulted in significant grain-size reduction. The original course-grained structure evolved from prolate bands of cells/subgrains enclosed by lamellar nonequilibrium grain boundaries (after the first two passes) towards an equiaxed homogeneous microstructure with equilibrium grain boundaries (after 8 passes). Significant changes in the volume fraction and the character of grain boundaries were observed both in Cu and in Cu -Zr alloy. Pronounced evolution of twin-related boundaries (R3 n grain boundaries) with strain (number of ECAP passes) was found in Cu while only a weak increase of R3 and R9 grain boundaries was observed in Cu -Zr alloys.

Ultra-fine grained (UFG) materials can be produced by several techniques involving severe plastic deformation (SPD). Accumulative Roll Bonding (ARB) is one of the SPD methods that enable the production of large amounts of UFG sheets. UFG sheets were prepared by up to six cycles of ARB at ambient temperature from an Al-0.22Sc-0.13Zr alloy in two states: a non-agehardened and a peak-aged. The effect of Al3(Sc1-xZrx) precipitates on the thermal stability of the UFG structures produced by ARB was investigated by isochronal annealing at temperatures between 200 and 550 °C. Additionally, the non-age-hardened ARB material was peak-aged prior to annealing and annealed together with both as-ARB-processed materials. The changes of microstructure and hardness due to annealing were studied. Annealing at 300 °C induces an additional strengthening in both non-pre-aged ARB materials that may be ascribed to precipitation and growth of coherent Al3(Sc1-xZrx) particles. This result suggests that the hardness decrease introduced by ARB in the peak-aged specimen is due to dissolution of precipitates during deformation. The annealing response of the materials above 300 °C does not depend on their thermal pre-treatment. However, the finely dispersed Al3(Sc1-xZrx) precipitates stabilise the refined deformed microstructure suitable for superplastic forming up to relatively high temperatures.

Study of the recrystallization of AW-5049 and AW-5754 twin-roll cast alloys by EBSD The paper presents the results of an investigation of the annealing response of sheets prepared from two twin-roll continuous cast aluminium -magnesium alloys. Sheets of 1 mm thickness prepared by cold rolling with 80 % reduction in thickness were annealed using an industrial regime with slow heating, holding at 350 8C and slow cooling. Hardness measurements and tensile tests allowed estimation of the magnitude of deformation recovery at different annealing stages. The evolution of the grain structure was studied by electron backscatter diffraction in a scanning electron microscope. The recrystallization in AW-5754 occurs at lower temperatures than in the AW-5049 material. The recrystallized grains are finer in the former alloy. The tensile properties of both AW-5754 and AW-5049 sheets are isotropic. Soft AW-5754 sheets exhibit less pronounced texture than AW-5049 ones.