摘要
Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of Hafnium （Hf） and explore the influence of lattice misfit on the ductility effect of Hr. It is found that though Hf prefers to substitute A1 rather than Ni in Ni3A1 phase within most of the investigated misfit range, its stronger preferring to Ni phase than NiaA1 phase makes it impossible to go into Ni3A1 phase to occupy A1 site in Ni-Ni3A1 alloys. Bond order analysis in Hf-free case shows that lattice misfit has different effects on the Griffith work of interfacial cleavage 27int/E and the maximum theoretical shear stress Zmax of Ni and Ni3A1, contributing to the existence of anomalous strength-temperature phenomena in NiaA1 alloys. However, the addition of Hf will make the 27int/E （or Zmax） of both Ni3A1 and Ni decrease （or increase） with lattice misfit, indicating that the addition of Hf may make the anomalous strength-temperature relationship in Ni3A1 region disappear locally.
Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of Hafnium （Hf） and explore the influence of lattice misfit on the ductility effect of Hr. It is found that though Hf prefers to substitute A1 rather than Ni in Ni3A1 phase within most of the investigated misfit range, its stronger preferring to Ni phase than NiaA1 phase makes it impossible to go into Ni3A1 phase to occupy A1 site in Ni-Ni3A1 alloys. Bond order analysis in Hf-free case shows that lattice misfit has different effects on the Griffith work of interfacial cleavage 27int/E and the maximum theoretical shear stress Zmax of Ni and Ni3A1, contributing to the existence of anomalous strength-temperature phenomena in NiaA1 alloys. However, the addition of Hf will make the 27int/E （or Zmax） of both Ni3A1 and Ni decrease （or increase） with lattice misfit, indicating that the addition of Hf may make the anomalous strength-temperature relationship in Ni3A1 region disappear locally.
基金
Acknowledgments The authors acknowledge the financial support from the National Natural Science Foundation of China （Nos. 51001001 and 51201002）. Prof. Y.M. Wang and Dr. H. Li are kindly thanked for helpful discussion and proof reading.
