the full annealing aa6061 aluminum alloy was subjected to severe plastic deformationvia the combination of equal channel angular pressing (ecap) and cold rolling (cr) in order torefine its microstructure and to improve its mechanical properties. according to the results of hotand cold tensile tests, the combination of ecap and cr significantly affected the final strengthand ductility of studied...

The tensile properties and deformation response of an ultrafine-grained (UFG) Al–Mg alloy with bimodal grain structure were investigated using a micro-straining unit and a strain mapping technique. Atomized Al 5083 powder was ball-milled in liquid N2 to obtain a nanocrystalline (NC) structure, then blended with 50 wt.% unmilled coarse-grained (CG) powder, and consolidated to produce a bimodal g...

Commercially pure nickel was processed by equal channel angular pressing (ECAP) through route Bc for 12 passes to obtain an ultrafine grained (UFG) microstructure and further subjected to an ultrasonic treatment (UST) which introduced a maximum amplitude equivalent to anormal stresses of 100 MPa in a steady state regime. It was observed that the microstructure of UFG Ni can be differently alter...

To gain insight into the origin of the ultra-high strength of ultrafine-grained (UFG) alloys, the solute clustering, precipitation phenomena, and microstructural evolutions were studied in an UFG Al-4.63Cu-1.51Mg (wt.%) alloy (AA2024) processed by high-pressure torsion (HPT). The thermal analysis was performed using differential scanning calorimetry. The microstructures, internal microstrains a...

Ultrafine-grained (UFG) pure copper of 280 nm grain size was prepared by equal-channel angular pressing. Tensile tests, strain-rate change tests and temperature change tests were conducted on UFG Cu in the temperature range between 77K and 373K. As usual, tensile strength increased as temperature decreased and strain rate increased. The activation energy of deformation increased linearly with t...

in the present study, the effect of grain size on the austenite stability was studied by nanoindentationtests in a 304l stainless steel. thermomechanical processing based on cold rolling and annealing wasused to produce two different types of austenite: ultrafine grained (ufg) austenite with the averagegrain size of 0.65 μm and coarse grained (cg) austenite with the average grain size of 12 μm....

Tensile tests were performed in situ on an ultrafine-grained (UFG) Al-Mg alloy using a micro-tensile module in a scanning electron microscope (SEM). The micro-strain evolution was tracked and measured using digital image correlation (DIC). A fine random speckle pattern was required to achieve high resolution and accuracy of strain measurement using DIC. To produce the speckle pattern, a pattern...

Ultrafine-grained (UFG) metallic materials processed by severe plastic deformation (SPD) techniques often exhibit significantly higher strengths than those calculated the well-known Hall-Petch equation. These result from fact that SPD processing not only forms UFG structure but also leads to formation of other nanostructural features, including dislocation substructures, nanotwins and nanosized...

The influence of Mo alloying on the thermal stability of grain size, dislocation density and hardness of ultrafine-grained (UFG) Ni alloys was studied. The UFG microstructure in alloys with low (∼0.3 at.%) and high (∼5 at.%) Mo contents was achieved by high-pressure torsion (HPT) performed for 20 turns at room temperature. The thermal stability of the two alloys was studied by calorimetry. A Cu...

Two different aspects of the thermal stability of grains were studied – (i) thermal stability of grain structure evolution during friction stir processing (FSP), and (ii) thermal stability of grains after FSP. It was concluded that Al3(Sc,Zr) dispersoids are effective in limiting grain growth to ultrafine grained regime (UFG) by stabilizing the microstructure during FSP. The presence of these d...