A compressive split-Hopkinson pressure bar and transmission electron microscope (TEM) are used to investigate the mechanical behavior and microstructural evolution of biomedical Ti alloy deformed at strain rates ranging from 8 · 10 2 s -1 to 8 · 10 3 s -1 at temperatures between 25°C and 900°C. In general, the results indicate that the mechanical behavior and microstructural evolution of the alloy are highly sensitive to both the strain rate and the temperature conditions. The flow-stress curves are found to include both a work-hardening region and a work-softening region. The strain-rate-sensitivity parameter, b, increases with increasing strain and strain rate but decreases with increasing temperature. The activation energy varies inversely with the flow stress and has a low value at high deformation strain rates and low temperatures. Microstructural observations reveal that the strengthening effect evident in the deformed alloy is a result primarily of dislocations and the formation of a phase. The dislocation density increases with increasing strain rate but decreases with increasing temperature. Additionally, the square root of the dislocation density varies linearly with the flow stress. Correlating the mechanical properties of the biomedical Ti alloy with the TEM observations, it is inferred that the precipitation of a phase dominates the fracture strain. Transmission electron microscope observations reveal that the amount of a phase increases with increasing temperature below the b-transus temperature. The maximum amount of a phase is formed at a temperature of 700°C and results in the minimum fracture strain observed under the current loading conditions.

This study investigates the multiwalled carbon nanotube as potential mechanical reinforcement in epoxy polymer. It is found that, by adding various concentrations of nanotube, both flow stress and fracture strain increased. Furthermore, the presences of the multiwalled carbon nanotubes are found to nucleate crystallization in the epoxy. This crystal growth is thought to enhance the strength of composite. The fracture surface analysis of the composite reinforced by carbon nanotube is used the scanning electron microscopy.

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In this study, the high strain rate deformation behavior and the microstructure evolution of Zr-Cu-Al-Ni metallic glasses under various strain rates were investigated. The influence of strain and strain rate on the mechanical properties and fracture behavior, as well as microstructural properties was also investigated. Before mechanical testing, the structure and thermal stability of the Zr-Cu-Al-Ni metallic glasses were studied with X-ray diffraction (XRD) and differential scanning calorimeter. The mechanical property experiments and microstructural observations of Zr-Cu-Al-Ni metallic glasses under different strain rates ranging from 10−3 to 5.1 × 103 s−1 and at temperatures of 25 °C were investigated using compressive split-Hopkinson bar (SHPB) and an MTS tester. An in situ transmission electron microscope (TEM) nanoindenter was used to carry out compression tests and investigate the deformation behavior arising at nanopillars of the Zr-based metallic glass. The formation and interaction of shear band during the plastic deformation were investigated. Moreover, it was clearly apparent that the mechanical strength and ductility could be enhanced by impeding the penetration of shear bands with reinforced particles.