| In the thesis,the lattice constants,crystal mass density,formation enthalpy,cohesive energy,elastic properties and electronic structures of 9 kinds of intermetallic compounds of Al-Pr intermetallic(Al4Pr?I4/mmm?,?-Al11Pr3?Immm?,Al3Pr?P63/mmc??Al2Pr?Fd???m?,?-AlPr?Pm???m?,?-AlPr?Cmcm?,AlPr2?Pnma?,?-AlPr3?P63/mmc?,?-AlPr3?Pm???m?)and crystals of Al and Pr were calculated by using the first-principles program CASTEP based on density functional theory.The calculated equilibrium lattice constant and mass density are in good agreement with the experimental values of previous studies.With the increase of the proportion of Pr atoms,the mass density of intermetallic compounds increases.And the alloying ability of Al-Pr intermetallic compounds first increased and then decreased.Their thermal stability decreases in order?-AlPr?Pm ???m?,?-AlPr?Cmcm?,Al2Pr?Fd???m?,?-AlPr3?P63/mmc?,AlPr2?Pnma?,?-AlPr3?Pm???m?,Al3Pr?P63/mmc?,?-Al11Pr3?Immm?,Al4Pr?I4/mmm?;It is found that the elastic properties of Al-Pr intermetallic compounds are better than that of matrix,and they are brittle.The elastic modulus of intermetallic compound single crystal of Al-Pr binary system shows anisotropy in space.Particular,?-Al11Pr3?Immm?,?-AlPr?Pm???m?and AlPr2?Pnma?single crystal Poisson's ratio in some particular direction will show a negative Poisson's ratio effect.The band structure calculation shows that Al-Pr binary intermetallic compounds are all conductors,their energy band structure is between-37 eV?-15 eV energy level,the contribution of Pr atomic orbital dominates,while between-15 eV?15 eV,the molecular orbital is composed of the hybrid of Al atomic orbital and Pr atomic orbital.Between energy levels -15 eV and 15 eV,the molecular orbitals of Al-Pr binary intermetallic compounds are mainly contributed by the Al-p,Pr-d and Pr-f orbitals.From the population distribution analysis and DOS,the Al-Pr intermetallic compounds are covalent and metallic. |
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