Effect of Ru on the Electronic Structure of the [100](010) Edge Dislocation in NiAl
Liqun CHEN1, Zhengchen QIU1, Tao YU2
1 College of Sciences, Central South University of Forestry & Technology, Changsha 410004, China ; 2 Division of Functional Materials, Central Iron and Steel Research Institute, Beijing 100081, China
Cite this article:
Liqun CHEN, Zhengchen QIU, Tao YU. Effect of Ru on the Electronic Structure of the [100](010) Edge Dislocation in NiAl. Acta Metall Sin, 2019, 55(2): 223-228.
NiAl intermetallics have potential application in the aerospace industry as a new high temperature structure material due to its high melting temperature, good thermal conductivity, low density, and good oxidation resistance. However, possible technological applications of NiAl are limited by its poor ductility at low temperatures and brittle grain boundary fracture at elevated temperature. Different methods have been dedicated to manage the brittle behavior of NiAl. Micro-alloying is a effective method. Dislocation is a complicated and widely existing crystal defect. The interaction between dislocation and impurity can greatly influence the mechanical properties of materials. However, the mechanism of interaction between the dislocation and alloying element is not clear. In the work, using the DMol and the discrete variational method within the framework of density functional theory, the site preference and alloying effect of Ru in the [100](010) edge dislocation core (DC) of NiAl are studied. The results of the impurity formation energy show that Ru exhibits a strong Al site preference. The analyses of the interatomic energy, the charge distribution and the partial density of states show that the strong bonding states are formed between the impurity atom and neighboring host atoms. Meanwhile, the bonds keep the atoms in the DC as a whole, which will benefit formation of kink. In addition, in the doped DC system, the interactions between the pair of atoms across the slip plane are weaker, while along the slip direction the interactions are stronger than those in the clean DC system. This bond characters may be in favor of the motion of [100](010) edge dislocation, which will improve the ductility of NiAl.
Fig.1 Atomic model of the [100](010) edge dislocation core in NiAl (Atoms denoted by solid circles and open circles construct two adjacent planes (plane A and plane B, respectively) in the stacking sequence along [001])
Atomic-pair
E / eV
E′ / eV
ΔERu / eV
Atom1-Ni6
-1.35
-1.45
-0.10
Atom1-Ni10
-1.03
-1.32
-0.29
Atom1-Al3
-0.71
-1.44
-0.73
Al2-Al8
-0.25
-0.14
0.11
Al2-Al3
-1.03
-0.82
0.21
Al3-Al4
-1.50
-1.78
-0.28
Ni10-Ni11
-0.93
-1.10
-0.17
Table 1 Interatomic energies for selected atomic pairs in the dislocation core (DC) with and without impurity
Fig.2 Charge density difference of the (001) plane including impurity in the doped dislocation system (The contour spacing is 0.002e/(a.u)3. Solid and dashed lines mean a gain and loss of charge, respectively)
Fig.3 Partial densities of state (PDOS) curves for impurities and neighboring host atoms in the clean DC (a) and the Ru-doped DC (b) (The Fermi level is shifted to zero. The Arabic numbers correspond to those in Fig.1)
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