First-principles calculations based on the density functional theory（DFT） and ultra-soft pseudopotential are employed to study the atomic configuration and charge density of impurity P in Ni Al Σ5 grain boundary（G...First-principles calculations based on the density functional theory（DFT） and ultra-soft pseudopotential are employed to study the atomic configuration and charge density of impurity P in Ni Al Σ5 grain boundary（GB）. The negative segregation energy of a P atom proves that a P atom can easily segregate in the Ni Al GB. The atomic configuration and formation energy of the P atom in the Ni Al GB demonstrate that the P atom tends to occupy an interstitial site or substitute a Al atom depending on the Ni/Al atoms ratio. The P atom is preferable to staying in the Ni-rich environment in the Ni Al GB forming P–Ni bonds. Both of the charge density and the deformation charge imply that a P atom is more likely to bond with Ni atoms rather than with Al atoms. The density of states further exhibits the interactions between P atom and Ni atom, and the orbital electrons of P, Ni and Al atoms all contribute to P–Ni bonds in the Ni Al GB. It is worth noting that the P–Ni covalent bonds might embrittle the Ni Al GB and weakens the plasticity of the Ni Al intermetallics.展开更多
In this paper,we employ the first-principle total energy method to investigate the effect of P impurity on mechanical properties of NiA1 grain boundary(GB).According to"energy",the segregation of P atom in N...In this paper,we employ the first-principle total energy method to investigate the effect of P impurity on mechanical properties of NiA1 grain boundary(GB).According to"energy",the segregation of P atom in NiA1E5 GB reduces the cleavage energy and embrittlement potential,demonstrating that P impurity embrittles NiA1E5 GB.The first-principle computational tensile test is conducted to determine the theoretical tensile strength of NiA1E5 GB.It is demonstrated that the maximum idea/tensile strength of NiA1E5 GB with P atom segregation is 144.5 GPa,which is lower than that of the pure NiA1E5 GB(164.7 GPa).It is indicated that the segregation of P weakens the theoretical strength of NiA1E5 GB.The analysis of atomic configuration shows that the GB fracture is caused by the interfacial bond breaking.Moreover,P is identified to weaken the interactions between A1-A1 bonds and enhance Ni-Ni bonds.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51201181)the Scientific Research Fund of Civil Aviation University of China(Grant No.08QD14X)
文摘First-principles calculations based on the density functional theory（DFT） and ultra-soft pseudopotential are employed to study the atomic configuration and charge density of impurity P in Ni Al Σ5 grain boundary（GB）. The negative segregation energy of a P atom proves that a P atom can easily segregate in the Ni Al GB. The atomic configuration and formation energy of the P atom in the Ni Al GB demonstrate that the P atom tends to occupy an interstitial site or substitute a Al atom depending on the Ni/Al atoms ratio. The P atom is preferable to staying in the Ni-rich environment in the Ni Al GB forming P–Ni bonds. Both of the charge density and the deformation charge imply that a P atom is more likely to bond with Ni atoms rather than with Al atoms. The density of states further exhibits the interactions between P atom and Ni atom, and the orbital electrons of P, Ni and Al atoms all contribute to P–Ni bonds in the Ni Al GB. It is worth noting that the P–Ni covalent bonds might embrittle the Ni Al GB and weakens the plasticity of the Ni Al intermetallics.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11404396 and 51201181)the Subject Construction Fund of Civil Aviation University of China(Grant No.000032041102)
文摘In this paper,we employ the first-principle total energy method to investigate the effect of P impurity on mechanical properties of NiA1 grain boundary(GB).According to"energy",the segregation of P atom in NiA1E5 GB reduces the cleavage energy and embrittlement potential,demonstrating that P impurity embrittles NiA1E5 GB.The first-principle computational tensile test is conducted to determine the theoretical tensile strength of NiA1E5 GB.It is demonstrated that the maximum idea/tensile strength of NiA1E5 GB with P atom segregation is 144.5 GPa,which is lower than that of the pure NiA1E5 GB(164.7 GPa).It is indicated that the segregation of P weakens the theoretical strength of NiA1E5 GB.The analysis of atomic configuration shows that the GB fracture is caused by the interfacial bond breaking.Moreover,P is identified to weaken the interactions between A1-A1 bonds and enhance Ni-Ni bonds.
