Study On The Structure And Stability Of {111}Edge Dislocation、Screw Dislocation、60°Dislocation In FCC Metal Aluminum At Finite Temperature

With the continuous development of aluminum industry,aluminum in all industrial application has been played an important role.As an important and basic metal materials,aluminum has been the subject worth further studying.In particular has now entered a new era of science and technology,high-precision aluminum needs and breakthrough of related core technology has been the driving force of continuous in-depth research and discussion on the fine structure and properties of aluminum materials.The properties of materials are determined by its structure,the application of the material is depended on its properties.Dislocation is a common defect in crystal materials,affecting the properties of materials.It is a basic premise of studying defect’s structure and properties for learning material’s performance.In this work,temperature effects on the core structure,core energy,Peierls stress etc.are comprehensively investigated for the edge dislocation,the screw dislocation and the 60°dislocation in metal aluminum by using fully discrete Peierls model.For the edge dislocation,the core clearly dissociates into partial dislocations with the separating distance D～12(?).The Peierls stress is very smalls_p(27)1KP a due to the large characteristic width and the small step length of the edge dislocation.The temperature effect is so weak for the edge dislocation that can be neglected.For screw dislocation,the weak dissociation with the separating distance D～5(?)is observed at low temperature.The screw dislocation gradually transformed into a compact one as temperature increase.There are two different core structures of screw dislocation at temperature T(29)700K,and thermal transition occurs between the two core structures,that is,the core structure can change from one structure to another.The Peierls stress of screw dislocation has a minimums_p～6.0MPaat the temperature T(28)700K,that is much smaller thans_p～.30MPa at room temperature.The 60°dislocation dissociates into 30°and 90°partial dislocation with the separating distance D～11(?),and the Peierls stress is abouts_p～1MPa.The temperature effect on the core structure of 60°dislocation is also weak.The core structures predicted theoretically are confirmed by numerical simulation based on the electronic density functional theory.