In this paper, cyclic flaring and sinking (CFS) as a new severe plastic deformation (SPD) method was employed to produce the ultrafine grain (UFG) copper tubes. The extra friction has eliminated in the CFS method that provided the possibility for production of longer UFG tubes compared to the other SPD methods. This process was done periodically to apply more strain and consequently finer grain...

the development of nano/ultrafine bainitic structure in aisi 52100 steel was the goal of this study. for this purpose,the aisi 52100 the specimens were austenitized at 1050 °c for 60 min followed by low-temperature austemperingtreatment at different temperatures and times. the austempered samples were characterized using field emissionscanning electron microscopy (fesem), x-ray diffraction (xrd...

Crushing and grinding of materials are the most common processes sample preparation for subsequent analysis industrial application. Recently, has become one popular methods producing nano-sized powders. This study investigates certain features grain transformation in process ores with finely dispersed valuable components order to liberate them, as well specifics metallurgical raw materials, met...

The influence of nanoscale reinforcement on the mechanical behavior of ultrafine-grained composites was studied. Al 5083 (Al– 4.5 Mg–0.57Mn–0.25Fe) composites, with grain size of 115 nm and B4C reinforcement size of 38 nm, were fabricated via cryomilling and consolidation. The result reveals that the presence of nanoparticles enhances strength by interacting with dislocations, while simultaneou...

A kinetic model for the diffusion-controlled annealing of excess vacancies under the experimentally relevant, non-isothermal condition of time-linear heating is presented and applied to dilatometry. The evolution of the vacancy concentration with time is quantitatively analyzed, considering as ideal sinks either dislocations or grain boundaries of spherical- or cylindrical-shaped crystallites. ...

Microwave sintering (MWS) of commercially available 15-nm-size nanocrystalline TiN powder was studied. Densification kinetics and grain growth mechanisms of nano-TiN were evaluated using non-isothermal heating up to 1500 °C with variable heating rates. A true nanocrystalline ceramic with ~80-nm-size grains and 94.5 % theoretical density was obtained via MWS consolidation at 1400 °C. At higher t...

An AM30 magnesium alloy was processed through ECAP method at 200 °C. Optical and transmission electron microscopy as well as electron back scattered diffraction (EBSD) technique were employed to characterize the deformed microstructure. A partially recrystallized microstructure including ultrafine/nano structures was obtained. The area fraction of 49% was measured for the recrystallized regions...

A 0.4C-2Si-1Cr-1Mo steel with an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure was fabricated by multipass caliber rolling at 773 K and subsequent annealing at 973 K. A static three-point bending test was conducted at ambient temperature and at 77 K. The strength-toughness balance of the developed steels was markedly better than that of conventionall...

Nano/submicron austenitic stainless steels have attracted increasing attention over the past few years due to fine structural control for tailoring engineering properties. At the nano/submicron grain scales, grain boundary strengthening can be significant, while ductility remains attractive. To achieve a nano/ submicron grain size, metastable austenitic stainless steels are heavily cold-worked,...

We report on molecular-dynamics (MD) simulations of tensile loading of nano-crystalline Al modeled by an embedded-atom method (EAM) potential. Usage of two different sample preparation methods of the nano-crystalline material allows us to compare mechanical properties for different sample qualities. A Voronoi-constructed polycrystal exhibits nearly no pores and has different mechanical properti...