An Al-Zn-Mg-Cu alloy without Sc or Zr additions was subjected to overaging and processing by equal channel angular pressing, obtaining a grain size of ∼160 nm and a fraction of high-angle boundaries of 56%. The high elongations attained at high strain rate (10-10 s) and low test temperature (250-300 oC) are attributed to the formation of new recrystallized grains, ∼500 nm in size, during heatin...

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The intriguing possibility of frictionless gliding of one solid surface on another has been predicted for certain incommensurate interfaces in crystals, based on Aubry's solution to the Frenkel-Kontorova model of a harmonic chain in a periodic potential field. Here we test this prediction for grain boundaries by comparing atomistic simulations with direct experimental observations on the struct...

Room-temperature tensile experiments on sub-micrometer freestanding thin films deposited at varied base pressures reveal two distinct classes of mechanical response. Samples that contain sufficient impurity concentrations to stabilize the microstructure against an applied stress show strong but brittle response. However, films that were deposited at lower vacuum base pressures that still allow ...

This paper investigates the microstructural evolution and grain refinement kinetics of a solution-treated Cu-0.1Cr-0.06Zr alloy during equal channel angular pressing (ECAP) at a temperature of 673 K via route BC. The microstructural change during plastic deformation was accompanied by the formation of the microband and an increase in the misorientations of strain-induced subboundaries. We argue...

Cyclically loaded disordered particle systems, such as granular packings and amorphous media, display a non-equilibrium phase transition towards irreversibility. Here, we investigate numerically the cyclic deformation of a colloidal polycrystal with impurities and reveal a transition to irreversible behavior driven by the displacement of dislocations. At the phase transition we observe enhanced...

Grain refinement through severe plastic deformation enables synthesis of ultrahigh-strength nanostructured materials. Two challenges exist in that context: First, deformation-driven grain refinement is limited by dynamic dislocation recovery and crystal coarsening due to capillary driving forces; second, grain boundary sliding and hence softening occur when the grain size approaches several nan...

A tensile sample of an Al-0.1Mg alloy was in-situ tested in a SEM followed by insitu annealing to develop recrystallizing nuclei/grains. The evolution of microstructure and crystallographic orientations were characterized using the EBSD technique. Changes in the same area within the sample during deformation and annealing steps were closely followed. During the deformation process the original ...

Hydrogen distribution in high-purity-based polycrystalline Al-5%Mg alloys prepared by changing the melting atmosphere was visualized by means of hydrogen microprint technique with electron backscattering pattern analysis after a tensile deformation at room temperature. The number of hydrogen atoms observed as silver particles on the slip lines was increased when the applied strain was increased...