Simulation Study Of Mechanical Behavior And Deformation Mechanism Of Nanostructural Al With High Stacking Fault Energy

Aluminum and its alloys are widely used in aviation,aerospace and electronic technology due to their excellent mechanical and physical properties such as high specific strength,lightweight and corrosion resistance.The construction of nano-structure or nano-twin structure is an effective method to improve the properties of metal materials,and also an important direction of the study on metal nanomaterials.However,the current research on the mechanical behavior and deformation mechanism of Al nanostructures with high dislocation energy is still very limited,due to the difficulty of experimental preparation.The mechanical behavior and deformation mechanism of Al nanostructures with higher dislocation energy under different loading directions,and the effects of twin spacing on mechanical properties and deformation mechanism of Al nanocrystals and temperature on Al nanocrystalsss.The main conclusions are as follows:（1）The mechanical properties and deformation mechanism of Al nanowires are different with different crystal orientation.It is found that the elastic module of Al nanowire along different crystal orientations displays the relationship of E^[111]>E^[110]>E^[100],which is generally true.The yield stress along different crystal orientations displays the relationship ofσ_y^[100]>σ_y^[111]>σ_y^[110],which is not generally true.Furthermore,the deformation mechanism of Al nanowire along crystal orientations is clarified according to the evolution of microstructures.And it is compared with the nanowires of Ni,Cu,Au and Ag.It is also found that it difficult to predict the deformation mechanism accurately by the Schmid factor and the stacking fault energy for Al nanowire with high fault energy in such small scale.（2）The mechanical properties and deformation mechanism of Al nanowires are different with different twin spacing.It is found that the transition from strengthening to softening occurs as the dislocation slips from inclined to twinning boundary to parallel to twinning boundary with the decrease of twinning spacing at small grain size,which is consistent with the pattern in nanotwin Ni and Cu.It is also found that there is a continuous strengthening effect due to strain localization.This is due to the nanotwin Al with higher dislocation energy,and the difficulty of dislocation nucleation affects the dependence of mechanical behavior on twin spacing with the decrease of twin spacing at large grain size.（3）The mechanical properties and deformation mechanism of Al nanowires are different with different temperature.It is found that the elastic modulus of Al with higher dislocation energy increases with the decrease of temperature.It is also found that the dislocation slips along the twin boundary and changes to slip along the twin boundary,so there is a transition from strengthening to softening as the twin spacing decreases,at high temperature.However,there is a continuous strengthening effect due to strain localization at low temperature.In addition,the critical temperature（T_s）of the average flow stress from continuous strengthening to strengthening-softening relationship decreases with the decrease of average grain size and twin spacing.