| Aluminum alloy is one of the most important engineering materials,which is widely used in aerospace,automobile and other fields because of its excellent properties such as light weight,plastic,low price and easy to conduct heat and electricity.However,the low mechanical strength limits the further expansion of its application range.Alloying is an important way to improve the performance of A1 alloy.Therefore,it is of practical significance to study the influence of alloying elements on the properties of A1 alloy.It is found that the interstitial interstitial solid solution formed by B,C,O and other small atomic elements can not only avoid the reduction of the toughness and corrosion resistance of the film due to high alloy content,but also show its unique growth structure and extraordinary strengthening efficiency,and at the same time reduce the preparation cost of the film.Therefore,doping B,C,O and other small atoms is one of the effective methods to improve the performance.In this paper,the first principle method is used to study the influence mechanism of solid solution structure and properties of Al-X(B,C,O)alloy.According to the analysis of solid solution binding energy,the binding energy of Al-X(B,C,O)is negative when the content does not exceed 3at.%,and the structure has thermodynamic stability.By comparing three forms of permutation solution,octahedral gap solution and tetrahedral gap solution,the atoms of B and C are solidly dissolved in Al crystals in the form of octahedral gaps with the largest spatial gaps,while O atoms are solidly dissolved in A1 crystals in the form of tetrahedral gapsThe mechanical properties of interstitial solid solution Al-X(B,C,O)alloys are complex.With the addition of B atoms,the elastic constant and elastic modulus of the alloy generally show a downward trend,and the degree of anisotropy is obviously weakened,while the ideal shear strength of Al-B is slightly reduced.Moreover,through the calculation of generalized stratification energy,it is found that the doping of B atom makes the maximum generalized stratification increase by 2 times,dislocation slip will be difficult in alloy deformation.With the addition and increase of C atoms,the elastic constants and elastic modulus of Al-C alloy tend to decrease,the degree of anisotropy was obviously reduced;moreover,the doping of C atoms not only improves the ideal strength of Al-C alloy,but also increases the maximum strain;in addition,the addition of C atoms reduced the maximum staggered energy of the alloy(by 10.26%)and made it relatively easy for the dislocation slip during deformation.The solid solution of O atoms is similar to that of C atoms,the solid solution of O atoms makes the overall elastic modulus of Al alloy slightly decrease and the degree of anisotropy significantly decrease,the ductility of the alloy reached its peak at 0.9at.%O.In the process of ideal shear deformation,when the strain value is 0.231,the maximum shear stress(3.37GPa)is obtained for Al-0 alloy,compared with pure Al,the ideal shear strength is obviously improved.In addition,solid solution O atoms reduced the maximum dislocation energy by 13.97%.By studying the density of States and the total density of states of Al-X(B,C,O),the electron at Fermi level is not zero,which shows that Al-X alloy shows obvious metallicity.We found that the mixed bond between B-Al is mainly covalent,while the mixed bond between C and O and Al is mainly ionic.The density of states at Fermi level is low,which further shows that Al-X(B,C,O)is a stable structure.These theoretical results play a very good guiding role in optimizing the composition of the new Al alloy,and can obtain the performance parameters that cannot be obtained in the experiment,and also provide some valuable research results for the study of Al alloy materials. |
