The results of tensile test in TEM for a brittle material, Ti-24Al-11Nb alloy, show that a lot of dislocations can also be emitted from a brittle crack tip and a dislocation-free zone (DFZ) is formed. The DFZ is an el...The results of tensile test in TEM for a brittle material, Ti-24Al-11Nb alloy, show that a lot of dislocations can also be emitted from a brittle crack tip and a dislocation-free zone (DFZ) is formed. The DFZ is an elastic zone with large strain and the stress in the DFZ may reach the cohesive strength of the material provided that the crack tip is sharp enough and the applied stress is large enough, resulting in initiating of a nanocrack in the DFZ or sometimes at the crack tip. The nanocrack formed in the DFZ is stable and will propagate into a deavage microcrack through multiplication and movement of dislocations in the plastic zone. Increasing the applied stress, the crack can stably propagate continuously or discontinuously.展开更多
TiAl can undergo severe corrosion, called cathodic corrosion, when cathodically charged with hydrogen in aqueous solutions or molten salt at 160℃. The mechanism of this phenomenon is experimentally discussed, and the...TiAl can undergo severe corrosion, called cathodic corrosion, when cathodically charged with hydrogen in aqueous solutions or molten salt at 160℃. The mechanism of this phenomenon is experimentally discussed, and the results are analysed.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘The results of tensile test in TEM for a brittle material, Ti-24Al-11Nb alloy, show that a lot of dislocations can also be emitted from a brittle crack tip and a dislocation-free zone (DFZ) is formed. The DFZ is an elastic zone with large strain and the stress in the DFZ may reach the cohesive strength of the material provided that the crack tip is sharp enough and the applied stress is large enough, resulting in initiating of a nanocrack in the DFZ or sometimes at the crack tip. The nanocrack formed in the DFZ is stable and will propagate into a deavage microcrack through multiplication and movement of dislocations in the plastic zone. Increasing the applied stress, the crack can stably propagate continuously or discontinuously.
文摘TiAl can undergo severe corrosion, called cathodic corrosion, when cathodically charged with hydrogen in aqueous solutions or molten salt at 160℃. The mechanism of this phenomenon is experimentally discussed, and the results are analysed.
