Investigation On Consolidation Processing Of Sub-micron/micron Aluminum Powders And Microstructure And Mechanical Properties Of The Consolidated Bulk Materials

This paper reports a study on the synthesis of a fully dense micrometric grained Alvia consolidation of spherical sub-micron/micron Al powders under a quasi-hydrostatichigh pressure of5GPa for3h at a temperature as high as560C and the investigation onmicrostructure and mechanical properties of the consolidated bulk materials.Micron/submicron aluminum powders were characterized using SEM. It is shown thatthese powders are spherical particles and the average powder size is (1.00.15) μm. It isshown by SEM analysis that the average grain size of as-HP materials is1.2μm,indicating a slight grain growth as compared with the average powder size. Duringconsolidation, oxide films on powder surfaces can be effectively disrupted into nano-scaleoxide particles (average size of～25nm) at grain boundaries. The as-consolidated Alexhibits both high strength (ultimate tensile strength of～130MPa) and ductility(uniform elongation of～10%).This paper also reports investigation on microstructure and mechanical properties ofbulk materials after cold rolling deformation and subsequent annealing which wereacquired by consolidating sub-micron/micron Al powders via SPS sintering. It is shown byTEM analysis that grain size of90%reduction of the rolling sample, with the increase oftemperature, decreased along the direction of length and broadened along the direction ofthickness slightly, subdivided continuously in the length. In addition, microstructureexhibited uniform lamellar state during250℃～400℃, the grain boundaries of partialregion had bowed at500℃, but some regions appeared broadening phenomenon and themost was still “bamboo” microstructure. Based on the spread of X ray diffraction peak, tocalculate the dislocation density of the90%reduction of the rolling sample under differentannealing temperature, the results shown that with the increasing of temperature,dislocation density of specimens of deformation decreased constantly. It is also shown byTEM analysis that as the strain accumulated, when the reduction of95%, dynamicrecovery happened, partial region recrystallized at500℃. Partial of the microstructurerecrystallized at600℃and partial of recrystallizition grains had grown up. Mechanical properties were shown by Vickers Microhardness, the results showed that VickersMicrohardness of90%reduction of the rolling sample is74HV and decreased withincreasing of the annealing temperature，in addition，Vickers Microhardness of95%reduction of the rolling sample is75HV and decreased rapidly with increasing of theannealing temperature, but they remained high hardness at high temperature。...