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Coarsening behavior of γ' particles in a nickel-base superalloy

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Rare metals 2009年第2期28卷 197-201页

作者： li, hongyu Zuo, lingli song, xiping wang, yanli chen, guoliang state key laboratory for advanced metals and materials University of Science and Technology Beijing Beijing 100083 China

The coarsening behavior of γ particles in a nickel-base superalloy FGH95 was investigated by means of experimental observations and growth kinetics calculations. The results show that when aging at 1000,1080 and 1140°C for different times,the relation of average particle size to time obeys the cube law ( a /2)3= kt,where k is 15.49 × 103,77.5 × 103 and 230.04 × 103 nm3/min,respectively. The particle size distributions are better fit to the LSW theoretical distributions when aging at 1000°C within 1440 min....

关键词： nickel-base superalloys γ particles coarsening behavior particle size distribution activation energy

MEAM Potential with Angular Dependence for TiAl

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Rare metals 2001年第1期20卷 13-17页

作者： Xiaodong Ni, Xitao wang, guoliang chen (Physics Department, university of science and technology beijing, beijing 100083, china state key laboratory for advanced metals and materials, university of science and technology beijing, beijing 100083, china) Univ Sci & Technol beijing Dept Phys Beijing 100083 Peoples R China Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China

The modified embedded atom method (MEAM) is an empirical extension of the embedded atom method (EAM) that includes angular forces. By fitted to the lattice constants, the cohesive energy, the APE (anti-phase boundary) energy, and the vacancy formation energy of TiAl, an accurate MEAM potential is obtained for the TiAl system with L10 structure. The calculation results of the properties of TiAl are in good agreement with experiments and the results of first principle (F.P.) calculations.

关键词： embedded atom method TiAl alloy angular dependence potential intermetallics

Mechanism of High Temperature Deformation in Cast Ti46Al8.5Nb0.2W Alloy

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Journal of university of science and technology beijing 2001年第4期8卷 290-294页

作者： Zicheng liu, Junpin lin, yanli wang, Zhi lin, guoliang chen state key laboratory for advanced metals and materials, university of science and technology beijing, beijing 100083, china Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China

Compression tests A ere conducted in the two phase Ti46Al8.5Nb0.2W alloy with a cast microstructure under the strain rates ranging from 2x10(-5) s(-1) to 10(-2) s(-1) at temperatures ranging front 900degreesC to 1100degreesC. It was found that there exist approximately linear relationships between the flow stress and the logarithm of strain rate at different temperatures. The strain rate dependence was analzed by the thermal activation theory and dislocation climbing is regarded as the controlling mechanism during high temperature compression tests.

关键词： Ti46%Al8.5%Nb0.2%W high temperature compression strain rate dislocation climbing

New Phase Ti_3Co_2Si in the Ti-Co-Si Ternary System at 1100℃

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Journal of materials science & technology 2000年第1期16卷 91-93页

作者： Xianhua HU, guoliang chen, Cinca Ion and Kequan NI (state key lab. for advanced metals and materials, university of science and technology beijing, beijing 100083, china) state key lab. for advanced metals and materials University of Science and Technology Beijing Beijing 100083 China

A new phase with the appropriate composition of Ti_3Co_2Si is found to exist at 1100℃. The X-ray diffraction of this phase can not be indexed by any other phase in the Ti-Co-Si ternary system and show this phase to b... 详细信息

关键词： Ti Co New Phase Ti3Co2Si in the Ti-Co-Si Ternary System at 1100 Si

Deformation-induced α_2/γ Interfaces in a Hot-deformed Ti-45Al-10Nb Alloy

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Journal of materials science & technology 1998年第2期14卷 132-138页

作者： Jinguo wang lichun ZHANG and guoliang chen (state key lab. for advanced metals and materials, university of science and technology beijing, beijing 100083, china )Henqiang YE(lab. of Atomic Imaging of Solids, Institute of Metal Research, Chinese Academy state key lab. for advanced metals and materials University of Science and Technology Beijing Beijing 100083 China lab. of Atomic Imaging of Solids Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

The structure change of α2/γ interface in a Ti-45Al-10Nb alloy induced by hot deformation was investigated by conventional and high-resolution transmission eIectron microscopy. Two types of hot deformation induced special α2/γ intedeces, coherent intedeces with high density of ledges and semi-coherent α2/γ intedeces were found to be due to the absorption of mobile dislocations into the α2/γ inteface. For the misoriented semi-coherent α2/γ interfaces, the densities of dislocation ledges increase with the misoriented angle between (111)γ and (0001)α2 planes, and 1/3[111] Frank partial dislocations were involved in the dislocation ledges. Formation mechanism of these deformation-induced α2/γ interfaces was discussed to be related to the role of α2/γ interface5 adjusting the deformation as a dislocation sink absorbing the slipping dislocations in the γ phase

关键词： Al Ti Interfaces in a Hot-deformed Ti-45Al-10Nb Alloy Deformation-induced

EAM Analysis of the Lattice Parameter Effect in Order-Disorder Transformation

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Journal of university of science and technology beijing 2001年第3期8卷 189-194页

作者： Timoth■e Nsongo, Xiaodong Ni, guoliang chen state key laboratory for advanced metals and materials, university of science and technology beijing, beijing 100083, china Faculty of science, Physics Department, P. O. Box 69, Brazzaville (CONGO) Applied Scie Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Fac Sci Dept Phys Brazzaville Rep Congo Univ Sci & Technol beijing Appl Sci Sch Beijing 100083 Peoples R China

The embedded atom method (EAM) was used to theoretically analyze the effect of the lattice parameter variation on the order-disorder transformation in binary alloys. Based on EAM, it is found that only one kind of order-disorder transition (second-order transition) exists for AB alloy. Three groups of order-disorder transformation can be observed for the A(3)B or AB(3) compounds. For group I, the order-disorder is a completely first-order transition. For group II, the order-disorder transformation is a classical first-order transition. For group III, the order-disorder transformation is found to be a second-order transition. The lattice parameter variations have a significant effect on E-2 coefficient, which is related to the ordering energy. These results are in good agreement with experiments.

关键词： order-disorder transformation embedded atom method (EAM) phase transformation binary alloy

Order-disorder Transformation for TiAl with L1_0 Structure at Stoichiometrical Composition

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Rare metals 2001年第3期20卷 147-151页

作者： Timothé e Nsongo, Xiaodong Ni,guoliang chen,Keh-Minn Chan 1) state key laboratory for advanced metals and materials, university of science and technology beijing, beijing 100083, china 2) Faculty of science (Physics Department, P.O. Box 69 Brazzaville, Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Fac Sci Dept Phys Brazzaville Rep Congo Univ Sci & Technol beijing Dept Phys Beijing 100083 Peoples R China W Virginia Univ Dept Mech & Aerosp Engn Morgantown WV 26506 USA

The embedded atom method (EAM) was used to study the order-disorder transformation in gamma -TiAl alloy with L1(0). structure at stoichiometrical composition, and the effect of lattice constants was also investigated. It was found that the gamma -TiAl alloy at stoichiometrical composition exhibits a second-order transition, and the relations between lattice constants a, c and the long-range order sigma are not linear. The lattice constant a decreases whereas c increases with the increase of the long-range order parameter. In this case the ordering induces the transformation from cubic to tetragonal. The change of the lattice constant during the ordering processes can be interpreted in terms of bond length.

关键词： order-disorder transformation TiAl long-range order intermetallic

Influence of Aluminum Content in γ-TiAl with L1_0 Structure during Ordering Processes

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Rare metals 2001年第4期20卷 230-235页

作者： Timothée Nsongot1,2 Xiaodong Ni1,3 guoliang chen1, Keh-Minn Chang4 1) state key laboratory for advanced metals and materials, university of science and technology beijing, beijing 100083, china 2) Faculty of science, P. 0. Box 69, Brazzaville, Congo Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Fac Sci Brazzaville Rep Congo Univ Sci & Technol beijing Dept Phys Beijing 100083 Peoples R China W Virginia Univ Dept Mech & Aerosp Engn Morgantown WV 26506 USA

Based on EAM (embedded atom method) interatomic potential, the effect of aluminum content on the type of order-disorder transformation (ODT) and the structure properties (lattice constants, volume, c/a ratio and configu- ration energy) during ordering processes was investigated for γ-TiAI based alloys. Results show that for the alloys with lower than 50%Al (all composition is in atom number fraction), the ODT is the first order transition, and the second order transition for the alloys with equal or higher than 50% Al. The increase of aluminum content results in the critical temperature increasing. The aluminum content has a very little effect on the lattice constants, the volume and the c/a ratio, but has a significant effect on the configuration energy. A metastable disordered state was found for the alloys with less than 50%Al.

关键词： TiA1 order-disorder transformation long-range order

Application of the Embedded-atom Method to liquid Binary Cu-Ni Alloys

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Journal of materials science & technology 1997年第2期13卷 117-122页

作者： Hongbo liU Kuiying chen Zhuangqi HU (state key lab. of RSA, Institute of Metal Research, Chinese Academy of sciences, Shenyang 110015, china)Geying AN(School of materials science and Engineering, Harbin Institute of technology, Harbin 150001, china) state key lab. of RSA Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China School of materials science and Engineering Harbin Institute of Technology Harbin 150001 China

A simple analytic embedded-atom model of monoatoms that includes more than nearest neighbours has been extended to study properties of binary liquid Cu-Ni alloys, here the two-body potential between different species of atoms is taken as a function of the two-body potential for the pure metals with a unique form which yields alloy models with the same invariance to electron density transformations as monoatomic models. Faber-Ziman structure factors have been computed by molecular dynamics simulation on the base of this model. The results are in good agreement with experimental data given by Waseda, thus supporting the overall validity of the approach, especially for cross potential of Cu-Ni pair. Further, a detailed description of structure of binary liquid Cu-Ni alloys with different compositions have been performed using pair analysis and bond orientational order method etc., and then the chemical short range order has also been examined to reveal the structural characterization.

关键词： Rev li Application of the Embedded-atom Method to liquid Binary Cu-Ni Alloys Cu Ni