Formation of the dislocation hoe zone(DFZ),and initiation and propagation of microcracks have been investigated by in situ transmission electron microscope(TEM)tensile test for NiAlFe intermetallics.When TEM foils are...Formation of the dislocation hoe zone(DFZ),and initiation and propagation of microcracks have been investigated by in situ transmission electron microscope(TEM)tensile test for NiAlFe intermetallics.When TEM foils are strained,a great number of dislocations are found to emit from a crack tip during microcrack propagation and drive out of the crack tip area,leaving behind a DFZ.The maximum normal stress exists in the DFZ, thus nanocracks initiate discontinuously ahead of the crack tip in the highly stressed DFZ. Connection of the main crack and nanocracks results in steady propagation of cracks.Cleavage fracture and bluntness of the crack tip indicate that propagation of the crack is a leaping process. The second phase in the NiAlFe alloy obstructs propagation of the crack, which results in deviation of the crack path.展开更多
文摘Formation of the dislocation hoe zone(DFZ),and initiation and propagation of microcracks have been investigated by in situ transmission electron microscope(TEM)tensile test for NiAlFe intermetallics.When TEM foils are strained,a great number of dislocations are found to emit from a crack tip during microcrack propagation and drive out of the crack tip area,leaving behind a DFZ.The maximum normal stress exists in the DFZ, thus nanocracks initiate discontinuously ahead of the crack tip in the highly stressed DFZ. Connection of the main crack and nanocracks results in steady propagation of cracks.Cleavage fracture and bluntness of the crack tip indicate that propagation of the crack is a leaping process. The second phase in the NiAlFe alloy obstructs propagation of the crack, which results in deviation of the crack path.
