First-principles Study Carbon Nanotubes Enhancing The MoSi₂ Matrix Composites

MoSi₂ is a structural material with great potential using in high-temperature field,with a attribute of high melting point,light density,good conductivity and thermal conductivity.But MoSi₂ inherent in the low temperature brittle and soft strength in high temperature limited in their field of aerospace applications. Therefore,in recent years,the MoSi₂ toughening of low-temperature and high temperature reinforcement materials has become a hot academic research all over the world.The main of the study is enhancing the material based on the theory of micro-alloy particles or based on the theory of fiber-reinforced whisker reinforced. Carbon nanotubes,since its excellent mechanical properties of composite materials is the first choice for reinforcements,in recent years,scholars take a lot time in the carbon nanotubes to enhance MoSi₂.In this paper,inventive use of first principles to systematic study the model of carbon atoms and carbon nanotubes enhancing the mechanical properties of MoSi₂ and electronic features.First of all,the mechanical properties of MoSi₂ single crystal with C11b structure,including elastic modulus,strain,breaking strength and electronic characteristics,had been study using first-principle.After that both carbon atoms and carbon nanotubes enhance MoSi₂ had been in-depth study,the attribue including characteristics of the plastic,electronic features.The mechanism of enhanced features and electronic effects no enhancment also had been analysis.The study focused on the fracture strength of composites,which was make up by carbon nanotubes enhancing the MoSi2 matrix.In fanal,a comparative study was taked between the results of first-principle and the experimental results.The study show that the key factor to improve low-temperature brittle of MoSi₂-based ceramic is raising the metal bond and improving the slip of <001> direction.Embedded carbon atoms in MoSi₂ can improve the crystal plastic,as a result,the covalent bond strength reducing combined with an increase of the system of metal,with little improvement in slip of single-crystal materials.The main roles of carbon nanotubes enhancing ceramic composite of MoSi₂ are deformation strain energy absorption,crack hinder and reducing the stress level of crack tip,with little improvement in slip of single-crystal materials.Through numerical analysis,fracture strength of the composites with carbon nanotubes enhancing increased with the CNTs percent,and consistent with experimental measured very well at low percent.Consquently,first-principle calculation studies have shown that the adoption of carbon atoms and carbon nanotube composites to enhance the role of MoSi₂ will have good results.