摘要
In situ tensile tests in a transmission electronmicroscope(TEM)show that dislocations emitted from a modelⅡcrack tipwill form a inverse piled-up group after equilibrium or a doublepiled-up group when they meet a obstruction, e.g., grain boundary orsecond phase. A microcrack can initiates in front of the piled-upgroup of dislocations. Micromechanics analysis shows thatdislocations emitted from a modelⅡblunt crack tip can form a inversepiled-up or double piled-up group, depending upon the applied stressintensity factor K_Ⅱa, lattice friction stressτ_f and the distanceof the obstruction from the crack tip L.
In situ tensile tests in a transmission electronmicroscope(TEM)show that dislocations emitted from a modelⅡcrack tipwill form a inverse piled-up group after equilibrium or a doublepiled-up group when they meet a obstruction, e.g., grain boundary orsecond phase. A microcrack can initiates in front of the piled-upgroup of dislocations. Micromechanics analysis shows thatdislocations emitted from a modelⅡblunt crack tip can form a inversepiled-up or double piled-up group, depending upon the applied stressintensity factor K_Ⅱa, lattice friction stressτ_f and the distanceof the obstruction from the crack tip L.
基金
[This project was financially supported by the special funds for the Major State Basic Research Projects (G19990650), Visiting Scholar Foundation of Key Laboratory of the Ministry of Education PRC and by the NNSF of China.]
