Simulation Of Effect Of Twin On Mechanical Property Of α-Fe

In this paper,nanostructured Bcc metal iron was selected and the deformation behavior of nano-twined iron under tensile loading was studied by means of molecular dynamics simulation.The effects of twins thickness,temperature,rotation angle of the twin boundary on the tensile properties were investigated.In addition,the influence of twin boundaries on crack propagation was studied.At the same time,the microscopic deformation mechanism of the nano-twinned iron was analyzed by visualization software(OVITO).The main research in this paper are listed as follow:(1)In this paper,the deformation behavior of the nano-twinned iron with different twin thickness and different temperature under tensile loading were studied.The results indicated that the young’s modulus and the yield strength of the nano-twinned iron increases with the increase of twin thickness,showing a inverse Hall-Petch relation.At the same time,the deformation mechanism is dominated by the deformation twins in the twin boundary,which deformation mechanism is coincident with the single crystal.The temperature has no effect on the deformation mechanism of nano twinned iron.The higher the temperature,the smaller the yield strength.(2)The effects of rotation angle and temperature on the mechanical behavior of nano twinned iron were studied.The results show that when the twin boundaries rotate a certain angle the yield stress decreases and the deformation is mainly detwinning and twinning,because of the increase of the Schmidt factor,the twin boundary is easier to slip.The temperature has no obvious effect on the deformation mechanism.(3)The deformation behavior of the crack vertical to the twin boundary and parallel to the twin boundary is studied.The results show that the introduction of twin boundaries could decrease the peak stress of the material and reduce the mechanical properties of the material.The deformation mechanism of the material is mainly dominated by the crack tip emission dislocation and crack propagation.When the twin boundary is perpendicular to the crack,the twin boundary hinders the crack propagation.