Ambient and cryogenic surface mechanical attrition treatments (SMAT) are applied to bcc iron plate. Both processes result in significant surface grain refinement down to the ultrafine-grained regime; the cryogenic treatment results in a 45% greater grain size reduction. However, the refined region is shallower in the cryogenic SMAT process. The tensile ductility of the grain size gradient remai...

a review on the microstructural evolution in magnesium alloys during severe plastic deformation waspresented. the challenges deserved to achieve ultrafine/ nanostructured magnesium were discussed.the characteristics of the processed materials are influenced by three main factors, including i)difficult processing at low temperatures, ii) high temperature processing and the occurrence ofdynamic r...

An ultrafine grain surface layer with average crystallite size of 28 nm was produced on annealed mild steel through a wire brushing process. The effects of grain size reduction on the inhibition performance of sodium phosphate were investigated using polarization and electrochemical impedance spectroscopy (EIS) measurements. The crystal grain size of wire brushed surface was analyzed by X-ray d...

Ultrafine-grained (UFG) Ti for improved mechanical performance as well as its surface modification enhancing biofunctions has attracted much attention in medical industries. Most of the studies on the surface etching of metallic biomaterials have focused on surface topography and wettability but not crystallographic orientation, i.e., texture, which influences the chemical as well as the physic...

Micro-forming with ultrafine-grained (UFG) materials is a promising direction for the fabrication of micro-electro-mechanical systems (MEMS) components due to the improved formability, good surface quality, and excellent mechanical properties it provides. In this paper, micro-compression tests were performed using UFG pure aluminum processed by equal-channel angular pressing (ECAP) with subsequ...

Materials with ultrafine grain sizes are attractive for use in micro-forming operations. High-pressure torsion (HPT) is an effective technique that allows disc materials subjected to torsional deformation to generate microstructures with significant grain refinement. Generally, ultrafine-grained materials exhibit high strength but their ductility is limited because they have both a low rate of ...

Ultrafine-grained (UFG) nanostructured materials having grain sizes of tens and hundreds of nanometers recently have aroused interest among researchers in the materials science field. With respect to their mechanical properties, one would hope to be able to obtain the extremely strong states that can be expected in the case of strong grain refinement according to the Hall-Petch relationship (Gl...

9 = 0.6 I / s ' 7 = 6.0 0 7 = 2 4 i ti 3 = 6 0 Through close control over green-state powder processing, pure alumina ceramics of 0.5-pm grain size were obtained by sintering at 1250°C. The static grain growth of this material was modest at temperatures below 1300°C. However, dynamic grain growth occurred rapidly during superplastic deformation. Therefore, although the ultrafine-grained alumina...

This work has two primary goals. The first is to advance our fundamental understanding of grain boundaries by making direct measurements of grain boundary thermodynamic properties using ultrafine-grained materials. The second is to explore possible deviations from conventional behavior at ultrafine grain sizes, specifically in regards to grain boundary thermodynamic properties and solute segreg...

Dynamic recrystallization (DRX) is an important grain refinement mechanism to fabricate steels with high strength and high ductility (toughness). The conventional DRX mechanism has reached the limitation of refining grains to several microns even though employing high-strain deformation. Here we show a DRX phenomenon occurring in the dynamically transformed (DT) ferrite, by which the required s...