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Posts Tagged ‘TWINNING (Crystallography)’

Room and elevated temperature mechanical properties in the as-extruded mg–al–ca–mn alloys






Abstract: Fine DRXed grains are formed in conjunction with coarse unrecrystallized regions in the as-extruded Mg–4Al–3Ca–0.3Mn (mass%) alloy produced by gravity casting technology. The unrecrystallized region exhibits strong basal texture whose basal plane is parallel to the extrusion direction. Yield anisotropy is appeared in the compressive test sample measured at ambient temperature due to formation of tensile twinning in the unrecrystallized region. The obtained 0.2% proof stresses in tension and compression are 331 and 285MPa, respectively. The yield anisotropy is improved when the test temperature increases, leading to remarkable elevated temperature mechanical properties. The room and elevated temperature mechanical properties are comparable to those in WE43A Mg and T6-treated A4032 Al alloys. [Copyright &y& Elsevier]


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Formation of multiple twins and their strengthening effect in nanocrystalline cu/zr multilayer films

Abstract: Multiple twins are experimentally observed within Cu grains in nanostructured Cu/Zr multilayer films. Formation of the multiple twins occurs through the sequential emission of partial dislocations not only from the grain boundaries but also from the Cu/Zr interfaces, which are driven by extremely high internal stresses and highly complex stress state caused by the inhomogeneous microstructures. The multilayers with multiple twins exhibit hardness higher than those with single or coplanar twins, indicative of a significant strengthening effect of the multiple twins. [Copyright &y& Elsevier]

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