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In this paper, PP (polypropylene) microstructures were manufactured by micro injection molding (MIM). The surface topography and internal defect under different process conditions were studied. An internal defect named ''hollow'' was observed in microstructures made without vacuum. To investigate the morphology (crystal and phase), the microstructures samples were cut to slices with 10 lm thickness along the filling direction. Results of polarized light microscopic observation reveal that these microstructures also represent ''skin-core'' morphology, i.e. a highly oriented non-crystalline skin layer, a shear zone with column crystal essentially parallel to the injection direction and a spherulites core. However the morphology distribution of microstructures is different from the macroscopic structure: the non-crystalline layer is much thinner, the ratio of skin layer (non-crystalline and column crystal layer) to core thickness is very big, there is no change of spherulites dimension from skin to center. So the microstructures must have a special mechanical performance differ from the macroscopic parts.

The superplastic deformation behaviour of a Ni-1 mass%SiC nanocomposite produced by pulse electrodeposition was investigated at temperatures of 410 C and 450 C and strain rates ranging from 8:3 Â 10 À4 to 5:0 Â 10 À2 s À1 . A maximum elongation of 836% was obtained at 450 C and a strain rate of 1:67 Â 10 À2 s À1 , which is the first observed result of the high strain rate and low temperature superplasticity for Ni-SiC nanocomposites. Scanning electron microscopy and transmission electron microscopy were employed to examine the microstructure of the asdeposited and deformed samples. The superplastic behaviour of the Ni-1%SiC nanocomposite was analysed through observations of its fracture surfaces and microstructures. The results showed that SiC nanoparticles play an important role in the stability of the microstructure of the Ni-SiC nanocomposite. A low volume fraction of cavity is necessary for a large elongation. The mechanisms of high strain rate and low temperature superplasticity of the composite are discussed in the paper.

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In this paper, the superplasticity of an electrodeposited nanocrystalline nickel with a grain size of 65 nm was examined under different strain rates and temperatures. A maximum elongation of 550% was obtained at a relatively low temperature of 450uC and a strain rate of 1 . 67610 23 s 21 . The strain rate sensitivity index is found to be .0 . 5 demonstrating its good superplasticity. The fracture surfaces and the deformed microstructures reveal that significant grain growth occurs during deformation, and it is found that the addition of SiC particles can effectively improve the superplasticity of the material. Experimental results further illustrate that the deformed microstructure is dependent on the strain rate, and the surface morphology of the material is relating to its oxidation phenomenon during deformation.

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5083 aluminium alloy superplastic forming adopted resistance heating can not only improve efficiency and cut energy but also generate electroplastic/electrosuperplastic effect to make the material deformation possess lower flow stress and higher plasticity. By analysing the influence of current on dislocation slipping, grain boundary migration and dynamic recrystallisation, it is found that the electron wind force can enhance the mobility of dislocations; meanwhile, the current also can reduce the activation heat of dislocation motion by joule heating effect. What is more, the grain size of resistance heating forming sample is significantly smaller than furnace heating, and the cavities in the sample become small and dispersive, so the resistance heating forming specimen possesses better performance.