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Abstract: SiCp/AZ91 magnesium matrix composite was fabricated by stir casting. The as-cast ingots were cut into cylindrical billets, and then forged at different temperatures (320, 370, 420, 470 and 520°C) at a constant RAM speed of 15mm/s with 50% reduction. The microstructure evolution of the composites during forging was investigated by optical microscope, scanning electron microscope, and transmission electron microscope. The texture of the forged composites was measured by neutron diffraction. Mechanical properties of the composite at different forging temperatures were tested by tensile tests at room temperature. It was found that a strong basal plane texture formed during forging, and the intensity of basal plane texture weakened as forging temperatures increased. The particle distribution in the composite was significantly improved by hot forging. Typical microstructures were obtained after forging at different temperatures and the composite with different microstructures offered different mechanical properties during tensile test. [Copyright &y& Elsevier]

Abstract: Carbon nanotube (CNTs) reinforced Mg matrix composites were successfully fabricated by a novel approach. After hot extrusion, the influence of CNTs on microstructure and mechanical properties of Mg–6Zn matrix was investigated. The results showed that most CNTs distributed uniformly and individually in the composites, and good interfacial bonding was achieved. CNTs significantly refined the grains of Mg–6Zn matrix, and the CNTs evidently improved the ultimate tensile strength (UTS), yield strength (YS) and Young's modulus. Grain refinement, load transfer mechanism and Orowan strengthening mechanism play important roles on the increase of the yield strength. [Copyright &y& Elsevier]

Abstract: The dynamic recrystallization (DRX) of a 10μm10% SiCp/AZ91 composite during hot compression was studied using optical microscope and transmission electron microscope. In the as-cast composite, SiC particles were segregated along grain boundaries, which was like necklaces along the grain boundaries. Thus, particles aggregated at transgranular areas while particles were almost absent at the grain interiors. During hot compression, particle deformation zones (PDZs) were formed near particles due to the mismatch between SiC particles and Mg matrix. DRX preferentially started near particles due to “particle-stimulated nucleation (PSN)” in PDZs. Therefore, this necklace particle distribution caused initiation of DRX along the pre-existing (initial) grain boundaries. As a result, the initial grain boundaries were entirely covered by new and fine DRX grains, and necklace structure of DRX grains was formed along the grain boundaries. As DRX further proceeded, DRX extended from the intergranular areas of the initial grains to the initial grain interiors. According to the microstructure investigations and analysis, the necklace mechanism for DRX was established for Mg matrix composites with necklace particle distribution. [Copyright &y& Elsevier]

sAbstract: The Mg/Al laminated composites were fabricated by the accumulative roll bonding (ARB) at ambient temperature using the pure magnesium and commercial pure Al sheets. Mg grains were refined after the primary sandwich preparation and then homogenized during the following ARB process while the grain size of Al layer decreased with increasing of the accumulated strains. Both the yield strength and ultimate strength along rolling direction and transverse direction increased gradually while the elongation to failure along both directions decreased with increasing of the ARB cycles. Formation of the Mg17Al12 phase indicated that the ARB process at ambient temperature could lead to a metallurgic bonding of the Mg/Al interface. [Copyright &y& Elsevier]