Deformed jadeite grains in the UHP jadeite-quartzites from the Dabie Mountains, eastern China show evidence (by transmission electron microscopy, TEM) of plastic deformation: free dislocations, dislocation loops, dislocation networks, dislocation arrays and regularly spaced subgrain boundaries by dislocation walls. Electron energy-loss spectroscopy and TEM studies reveal the existence of water-rich bubbles within dislocations and imply a relationship with water-defect dislocation by water weakening in the jadeites. These observations suggest that the water-rich bubbles are a major weakening effect facilitating plastic deformation of jadeite by dislocation creep.

This article aims to provide a fundamental understanding of the deformation mechanisms of NiTi shape memory alloy (SMA) during the wear process at different temperatures when different microstructures are present. Three temperature regimes were selected namely, T < Mf, As < T < Af, and T > Af, where fully martensitic, martensite co-existing with austenite, and fully austenitic microstructures were formed, respectively. When T < Mf, it was observed that the coefficient of friction had decreased initially and thereafter stabilized at a lower value with increasing wear cycles. More decrease was found when the temperature was near to As. Furthermore, when tested above Af, the coefficient of friction had decreased more significantly under higher load. Difference in the trend of coefficient of friction at different temperatures is originated from the different deformation mechanisms involved in the wear process, particularly the martensite detwinning process, the stress-induced phase transformation process, and the plastic deformation of martensite.

Deformation mechanisms of a ZrTiAlV alloy with two ductile phases including a hexagonal close-packed (hcp) structure phase were investigated. A ZrTiAlV alloy was prepared via smelting, breakdown, forging, and suitable heat treatments. X-ray diffraction results show that the proposed ZrTiAlV alloy has two ductile phase structures, namely, hcp structure α-phase and bcc (body-centered cubic) structure β-phase. Scanning electron microscopy (SEM) results show that the plastic deformation of the examined ZrTiAlV alloy starts from the α-phase. Transmission electron microscopy (TEM) analysis shows that only dislocation slips can be found near fractured areas, and the main slip plane in the α-phase is the (0001) lattice plane. Both of the SEM and TEM results show the inexistence of deformation twin in the examined ZrTiAlV alloy including a hcp structure α-phase. Reasons for the abnormal deformation behavior of the hcp structure α-phase are also discussed.

The effects of temperature and alloying elements on deformation in the high-strain-rate regime were investigated by testing fine-grained magnesium alloys with an average grain size of 2 ∼ 3 μm by a nanoindentation technique. The dynamic hardness measurements aligned well with existing quasistatic data, together spanning a wide range of strain rates, 10−3 ∼ 150/s. The high-rate hardness was influenced by various alloying elements (Al, Li, Y and Zn) to different degrees, consistent with expectations based on solid solution strengthening. Transmission electron microscopy observations of the indented region revealed no evidence for deformation twins for any alloying elements, despite the high strain-rate. The activation energy for deformation in the present alloys was found to be 85 ∼ 300 kJ/mol within the temperature range of 298 ∼ 373 K, corresponding to a dominant deformation mechanism of dislocation glide.