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Deformable SiCp/Al composites with lower volume fractions (15%, 20%, 25%) of the SiC particle reinforcement were fabricated by a squeeze casting technique. The volume fraction of the SiC particle was controlled by adding aluminum powder into the preform. The deformability of the SiCp/Al composites was studied by hot extrusion and the effect of the hot extrusion on microstructure and properties of the composites was investigated. The results show that the SiCp/Al composites fabricated by the modified squeeze casting method used here could be extruded successfully by the extrusion ratios of 9:1, 16:1, 25:1, 36:1, respectively. The strength, modulus and tensile elongation of the composites were improved by the hot extrusion. The resulting microstructure of the composites in both as cast and extrusion states was observed and analyzed by using SEM and TEM.

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The compressive properties characterized as a function of the true stress-strain response of the ferritic oxide dispersion strengthened (ODS) alloys, fabricated by mechanical alloying, were examined at strain rates ranging from 0.01 to 0.5s-1. Based on the differential scanning calorimeter (DSC) analysis, the solidus temperature of the ferritic ODS alloys is 1446oC. Therefore, the compressive temperatures were chosen to be from 1050oC to 1300oC. Transmission electron microscopy (TEM) observation is indicative of the homogeneous distribution of the nano-yttria particles with the granularity of 100~200nm, which may exert a strong pinning effect on subgrains. The results indicate that flow stress of the ferritic ODS alloys enhances with decreasing compressive temperature and increasing strain rate. Investigation of the strain rate sensitivity exponent and apparent activation energy of the ferritic ODS alloys has been carried out in detail.

The compressive properties characterized as a function of the true stress-strain response of -Si3N4 whisker reinforced 4032 aluminum alloy composite were examined at strain rates ranging from 10-3 to 100s-1 in the temperature interval 500~620oC. The effect of compressive deformation parameters such as strain rate and temperature on the mechanical behavior was systematically investigated. The strain rate sensitivity exponent and activation energy were calculated. The activation energy is 126 KJmol-1 at 500oC to 540oC, close to that for lattice self-diffusion in aluminum (142KJmol-1), and is 210 KJmol-1 at 540oC to 580oC ( =0.37s-1). The compressive deformation behavior of the composite can be described quantified by the Zener-Hollomon parameters (Z) for the solid state and the Non Newton-fluid for the semi-solid state of the composite. It is demonstrated that a linear equation of the logarithmic Z fits the flow stress of the composite at elevated temperatures. The compressive deformation mechanisms of the -Si3N4w/4032Al composite were discussed preliminarily.