Two different types of shear bands generate in ultrafine-grained (UFG) CoCrFeMnNi high-entropy alloys deformed at 77 K, i.e. commonly-observed low angle grain boundary (LAGB) type and unusual twin-coupled type. Twin-coupled exhibit a misorientation 56–67° with the matrix, contrast to LAGB band 6–12°. Both annealing twins deformation can act as precursor for bands, where dislocation accumulation...

Al 5083 alloy powder was mechanically milled in liquid nitrogen to achieve a nanocrystalline (NC) structure having an average grain size of 50 nm with high thermal stability, and then consolidated by quasi-isostatic (QI) forging. The consolidation resulted in ultrafine grains (UFG) of about 250 nm, and the bulk material exhibited enhanced strength compared to conventionally processed Al 5083. T...

The monotonic and cyclic deformation behavior of ultrafine-grained metastable austenitic steel AISI 304L, produced by severe plastic deformation, was investigated. Under monotonic loading, the martensitic phase transformation in the ultrafine-grained state is strongly favored. Under cyclic loading, the martensitic transformation behavior is similar to the coarse-grained condition, but the cycli...

Recent studies have shown that nanotwinned copper (NT Cu) exhibits a combination of high strength and moderate ductility. However, most engineering and structural applications would also require materials to have superior fracture toughness and prolonged subcritical fatigue crack growth life. The current study investigates the effect of twin density on the crack initiation toughness and stable ...

Equal channel angular pressing (ECAP) was performed on ZK60 alloy and pure Mg in the temperature range 150-250 °C. A significant grain refinement was detected after ECAP, leading to an ultrafine grain size (UFG) and enhanced formability during extrusion process. Comparing to conventional coarse grained samples, fracture elongation of pure Mg and ZK60 alloy were significantly improved by 130% an...

ABSRACT A comparative study of the surface microstructural changes after fatigue in an ultrafine grained and coarse grained aluminum alloy was performed using orientation imaging microscopy (OIM). The fraction of low angle boundaries with misorientation less than 2.5 ̊ increased for both the coarse and ultrafine grained alloys. A consistent decrease in the fraction of low angle boundaries, with ...

fabrication of ultrafine grained materials by imposing severe plastic deformation for improvement of mechanical and physical properties of metals has been the focus of many researches over the past few years. in this process, a sheet is subjected to repetitive shear deformation conditions by utilizing asymmetrically grooved and flat dies through alternate pressing. in this study, a 2mm thick co...

The service life of technical components is often limited by the fatigue strength deployed materials. accumulative roll bonding (ARB) process, which has ability to produce ultrafine‐grained (UFG) laminated metal composites with tailored properties, offers a unique method significantly enhance materials that are cyclically loaded in three‐point bending. Detailed microstructural investigations re...

In this paper, the study of efficient bonding characteristics of AA6014 and AA1050 metal strips is carried out for Accumulative Roll Bonding (ARB) process. Among various Severe Plastic Deformation (SPD) techniques, ARB process is widely used due to its ability to produce ultra-fine grained ( UFG) or nanostructured bulk material. It has been observed that, if the experimental pressure and corres...

Equal channel angular pressing results in ultrafine-grained (approximately 200-500 nm) Ti with superior mechanical properties without harmful alloying elements, which benefits medical implants. To further improve the bioactivity of Ti surfaces, Ca/P-containing porous titania coatings were prepared on ultrafine-grained and coarse-grained Ti by micro-arc oxidation (MAO). The phase identification,...