Ru对NiAl[100](010)刃型位错电子结构的影响
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摘要
利用DMol和离散变分法,研究了Ru在NiAl [100](010)刃型位错中择优占位和合金化效应。杂质偏聚能的计算结果表明,Ru会优先占据Al心位错芯中的Al格位。原子间相互作用能、电荷密度和态密度的分析表明,杂质原子和相邻基体原子之间形成了较强的化学键,使Ru原子与位错芯区近邻基体原子间因强相互作用形成一个整体。此外,在掺杂体系中,穿过滑移面的基体原子间相互作用减弱,而沿滑移方向基体原子间的相互作用加强。这样的成键特性有利于位错线沿滑移面的移动形成扭折,扭折的成核及迁移促使位错运动,从而改善NiAl合金的韧性。
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.
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.
引文
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[19]Ponomareva A V,Vekilov Y K,Abrikosov I A.Effect of Re content on elastic properties of B2 NiAl from ab initio calculations[J].J.Alloys Compd.,2014,586:S274
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[24]Guenzburger D,Ellis D E.Magnetism of Fe impurities in alkalineearth metals and Al[J].Phys.Rev.,1992,45B:285
[25]Wang C Y,Yue Y,Zeng Y P,et al.Electronic structure of edge dislocation in Iron[J].Sci.China,1993,36A:1261
[26]Stoloff N S,Koch C C,Liu C T,et al.High-temperature ordered intermetallic alloys II[A].MRS Symposia Proceeding No.82[C].Pittsburgh:Materials Research Society,1987:175
[27]Balasubramanian M,Pease D M,Budnick J I,et al.Site-occupation tendencies for ternary additions(Fe,Co,Ni)in b-phase transition-metal aluminides[J].Phys.Rev.,1995,51B:8102
[28]Daniel M,Balasubramanian M,Brewe D,et al.Site selectivity and bonding in the b-phase aluminides:Studies of RuAl,PdAl,and Pd and Ru dopants in NiAl[J].Phys.Rev.,2000,61B:6637
[29]Wang C Y.Energetics of metallic defect and electronic structure of doped grain boundary[J].Acta Metall.Sin.,1997,33:54(王崇愚.金属缺陷能量学基础及掺杂晶界电子结构[J].金属学报,1997,33:54)
[30]Wang C Y.Electronic structure of impurity-defect complexes in metals[J].Defect Diffus.Forum,1995,125-126:79
[2]Grabke H J.Oxidation of NiAl and FeAl[J].Intermetallics,1999,7:1153
[3]Darolia R,Walston W S,Noebe R,et al.Mechanical properties of high purity single crystal NiAl[J].Intermetallics,1999,7:1195
[4]Dong H X,Jiang Y,He Y H,et al.Formation of porous Ni-Al intermetallics through pressureless reaction synthesis[J].J.Alloys Compd.,2009,484:907
[5]Jiang D T,Guo J T.Preliminary investigation of in-situ multi-phase composite NiAl/Cr(Mo)-TiC[J].Mater.Lett.,1998,36:33
[6]Ishide K,Kainuma R,Ueno N,et al.Ductility enhancement in NiAl(B2)-base alloys by microstructural control[J].Metall.Trans.,1991,22A:441
[7]Wei H,Liang J J,Sun B Z,et al.Comparison of valence-band structures of NiAl alloy containing Cr and Ti:Photoelectron spectrum and first-principles calculations[J].Intermetallics,2010,18:1062
[8]Zhang J F,Shen J,Shang Z,et al.Microstructure and room temperature fracture toughness of directionally solidified NiAl-Mo eutectic in situ composites[J].Intermetallics,2012,21:18
[9]Adharapurapu R R,Zhu J,Dheeradhada V S,et al.Effective Hf-Pd Co-doped b-NiAl(Cr)coatings for single-crystal superalloys[J].Acta Mater.,2014,76:449
[10]Sheng L Y,Guo J T,Lai C,et al.Effect of Zr addition on microstructure and mechanical properties of NiAl/Cr(Mo)base eutectic alloy[J].Acta Metall.Sin.,2015,51:828(盛立远,郭建亭,赖琛等.Zr添加对NiAl/Cr(Mo)基共晶合金微观组织和力学性能的影响[J].金属学报,2015,51:828)
[11]Levit V I,Bul I A,Hu J,et al.High tensile elongation of b-NiAl single crystals at 293K[J].Scr.Mater.,1996,34:1925
[12]Han P,Qi Y H,Guo J T.Microstructure and elevated temperature tensile behavior of directionally solidified Ni-rich NiAl-Mo(Hf)alloy[J].J.Mater.Sci.Technol.,2011,27:437
[13]Wang L,Shen J,Shang Z,et al.Microstructure and mechanical property of directionally solidified NiAl-Cr(Mo)-(Hf,Dy)alloy at different withdrawal rates[J].Mater.Sci.Eng.,2014,A607:113
[14]Kontsevoi O Y,Gornostyrev Y N,Freeman A J,et al.Electronic mechanism of impurity-dislocation interactions in intermetallics:NiAl[J].Philos.Mag.Lett.,2001,81:455
[15]Chen L Q,Yu T,Peng X F,et al.The site preference of refractory element W in NiAl dislocation core and its effects on bond characters[J].Acta Phys.Sin.,2013,62:117101(陈丽群,于涛,彭小芳等.难熔元素钨在NiAl位错体系中的占位及对键合性质的影响[J].物理学报,2013,62:117101)
[16]LüB L,Chen G Q,Qu S,et al.Effect of alloying elements on<111>dislocation in NiAl:A first-principles study[J].Physica,2013,417B:9
[17]Bochenek K,Basista M.Advances in processing of NiAl intermetallic alloys and composites for high temperature aerospace applications[J].Prog.Aerosp.Sci.,2015,79:136
[18]Ning L K,Tong J,Liu E Z,et al.Effect of Ru on the solidification microstructure of a Ni-based single crystal superalloy with high Cr content[J].Acta Metall.Sin.,2017,53:423(宁礼奎,佟健,刘恩泽等.Ru对一种高Cr镍基单晶高温合金凝固组织的影响[J].金属学报,2017,53:423)
[19]Ponomareva A V,Vekilov Y K,Abrikosov I A.Effect of Re content on elastic properties of B2 NiAl from ab initio calculations[J].J.Alloys Compd.,2014,586:S274
[20]Wang Y L,Jones I P,Smallman R E.The effects of iron on the creep properties of NiAl[J].Intermetallics,2006,14:800
[21]Delley B.An all-electron numerical method for solving the local density functional for polyatomic molecules[J].J.Chem.Phys.,1990,92:508
[22]Delley B.Analytic energy derivatives in the numerical localdensity-functional approach[J].J.Chem.Phys.,1991,94:7245
[23]Ellis D E,Painter G S.Discrete variational method for the energyband problem with general crystal potentials[J].Phys.Rev.,1970,2B:2887
[24]Guenzburger D,Ellis D E.Magnetism of Fe impurities in alkalineearth metals and Al[J].Phys.Rev.,1992,45B:285
[25]Wang C Y,Yue Y,Zeng Y P,et al.Electronic structure of edge dislocation in Iron[J].Sci.China,1993,36A:1261
[26]Stoloff N S,Koch C C,Liu C T,et al.High-temperature ordered intermetallic alloys II[A].MRS Symposia Proceeding No.82[C].Pittsburgh:Materials Research Society,1987:175
[27]Balasubramanian M,Pease D M,Budnick J I,et al.Site-occupation tendencies for ternary additions(Fe,Co,Ni)in b-phase transition-metal aluminides[J].Phys.Rev.,1995,51B:8102
[28]Daniel M,Balasubramanian M,Brewe D,et al.Site selectivity and bonding in the b-phase aluminides:Studies of RuAl,PdAl,and Pd and Ru dopants in NiAl[J].Phys.Rev.,2000,61B:6637
[29]Wang C Y.Energetics of metallic defect and electronic structure of doped grain boundary[J].Acta Metall.Sin.,1997,33:54(王崇愚.金属缺陷能量学基础及掺杂晶界电子结构[J].金属学报,1997,33:54)
[30]Wang C Y.Electronic structure of impurity-defect complexes in metals[J].Defect Diffus.Forum,1995,125-126:79