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Cyclic oxidation behavior of Ni_(3)Al-based single crystal alloy IC21

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Rare Metals 2023年第5期42卷 1656-1662页

作者： Tian-Tian Yang Xin Zhou shu-suo li Yan-ling Pei Sheng-Kai Gong School of Materials Science and Engineering Beihang UniversityBeijing100191China

In this study,the cyclic oxidation tests of the Ni3Al-based single-crystal super alloy IC21 were carried out at 800,900,950,1000,1050 and 1100℃in *** present study shows that the complex oxide scale on the surface of the alloy is made up of an outer columnar NiO layer,an intermediate mixture of NiO and NiAl2O4layer with a small amount of Mo oxides and an inner continuous layer ofα-Al_(2)O_(3).The cyclic oxidation kinetics curves show that oxidation resistance at 800,900,950,1000 and1050℃seems to follow a similar law and is better than that at 1100℃.The overall weight changes at 1100℃follows a parabolic *** and severe rumpling of the oxide scale are observed on the surface of the alloy at1100℃,revealing the occurrence of disastrous oxidation.

关键词： Ni_(3)Al Thermal cycling Oxidation Microstructure

Partitioning behavior and lattice misfit of γ/γ’phases in Ni-based superalloys with different Mo additions

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Rare Metals 2021年第4期40卷 920-927页

作者： Zhe Ma Yan-ling Pei liang Luo Lu Qin shu-suo li Sheng-Kai Gong School of Materials Science and Engineering Beihang UniversityBeijing 100191China

A low-density single crystal(LDS) alloy with the composition of high Mo content was *** extra 1.5 wt% Mo was added in the Alloy A with the composition of Ni-6.5 Al-8.0 Mo-2.4 Cr-6.2 Ta-4.9 Co-1.5 Re-(0.01-0.05) Y(wt%) to study the influence of Mo on the lattice parameter and partitioning *** electron microscope(SEM) with energy-dispersive spectrometer(EDS),transmission electron microscopy(TEM)and high-temperature X-ray diffraction(HT-XRD) were used to observe the microstructure,analyze the elemental content and measure the lattice parameter of the *** natural lattice misfit was calculated by lattice constants which were measured by HT-XRD at the temperature from 25 to 1150℃,and the results showed that the lattice misfit would be more and more negative with temperature *** was found that 1.5 wt% addition of Mo will increase the absolute value of the lattice misfit of γ/γ’phases and the volume fraction of γ’,and at the same time,influence the elemental distribution in γ and γ’ phases,especially Re and *** has a higher partitioning ratio(k) after the addition of Mo.

关键词： Ni-based superalloys Mo Lattice misfit High-temperature X-ray diffraction(HT-XRD) Partitioning behavior

Effect of trace Ce on high-temperature oxidation behavior of an Al-Sicoated Ni-based single crystal superalloy

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Journal of Iron and Steel Research International 2019年第1期26卷 78-83页

作者： Xiao-juan Pang shu-suo li Lu Qin Yan-ling Pei Sheng-kai Gong School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Ni-based single crystal superalloy IC21 with different Ce con tents was prepared by screw selection method,and Al-Si coatings were prepared by pack *** oxidation and transient oxidation were carried out at 1150℃ to investigate the effect of Ce on the high-temperature oxidation behavior of Al-Si *** cyclic oxidation at 1150℃,the addition of trace Ce decreased the mass gain of the Al-Si-coated samples and effectively improved oxidation perform a nee and spallation *** specimens without Ce doping,microstructure examinatio n revealed that bulkyγ-Ni3Al precipitated in oxidized coating because of high Al con sumption,and this finding suggests that Ce inhibits the consumption of Al in the coating during *** slows down the Ininsformation of O-Al2O3 to oc-Al2O3 and improves the adhesion of the oxide scale.

关键词： Single crystal superalloy Trace Ce Al-Si coating Oxidation behavior AlO3

Improved mechanical properties of Ni-rich Ni3Al coatings produced by EB-PVD for repairing single crystal blades

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Rare Metals 2017年第7期36卷 556-561页

作者： Jing-Yong Sun Yan-ling Pei shu-suo li Hu Zhang Sheng-Kai Gong School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Active control of turbine blade tip clearance for aircraft engine continues to be a concern in engine opera- tion, because turbine blades are subjected to wear and therefore cause an increasing tip clearance between the rotating blades and the shroud and also reduce the engine efficiency. In this work, a Ni-rich Ni3A1 coating with γ＇/γ two-phase microstructure was deposited by electron beam physical vapor deposition （EB-PVD）, which worked as repairing the worn blade tips of single crystal blades. Nb molten pool was used to increase the molten pool tem- perature and thus to enhance the deposition rate. The microstructures and mechanical properties can be modified by the deposition temperatures and the following heat treatments. All coatings consist of γ＇ and γ phases. At deposition temperature of 600 ℃, a dense microstructure can be achieved to produce a coating with grain size of 1 μm and microhardness of -HV 477. After being heated for 4 h at a temperature of 1,100 ℃, the coatings have a more uniform microstructure, and microhardness maintains at a high level of -HV 292. Effect of Hf and Zr on EB-PVD Ni3Al repair coating will be further investigated.

关键词： Repair coating Ni3A1 Electron beamphysical vapor deposition Blades tips Single crystal Heat treatment

Effect of applied stress on r'-rafting behavior in a Ni-based singlecrystal superalloy:experiments and finite element analysis

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Journal of Iron and Steel Research International 2019年第3期26卷 259-267页

作者： Yuan-chao Yu Yi Ru Yong Shang Yan-ling Pei shu-suo li Sheng-kai Gong School of Materials Science and Engineering Beihang University Beijing 100191 China

The effect of applied tensile stress on the r'-rafting behavior for a Ni-based single-crystal superalloy with more negative misfit was *** conducting interrupted creep tests at high temperature,it indicated that the increase in the applied stress accelerates the r'-rafting(directional coarsening of yr phase).In the early stage of rafting,the r'-cubes start interconnecting at the ends of the parallel-to-applied-stress r'-*** distributions of misfit stress,coherent strain and strain energy density of the r/r'phases are then calculated by finite element *** calculation results show that the rafting acceleration is mainly ascribed to the reduced strain energy density in the parallel-to-applied-stress r'-channel that is driven from the couple interaction of external load and misfit *** dislocation network formation,resulting from the misfit-induced increase in resolved shear stress,also contributes to the r'-rafting.

关键词： Ni-based superalloy High lattice misfit Rafting Finite element analysis Misfit stress Strain energy density

Effects of Ru on microstructure stability and mechanical properties of Ni3Al single crystal alloy

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Progress in Natural Science:Materials International 2011年第4期21卷 286-292页

作者： shu-suo li,Xiao-ying XIE,li-wu JIANG,Ya-fang HAN School of Materials Science and Engineering,Beihang University,Beijing 100191,China School of Materials Science and Engineering Beihang University Beijing 100191 China

The effect of Ru on microstructure stability and stress rupture properties of a Ni3Al single-crystal alloy was investigated. The experimental results showed that the addition of 2%Ru(mass fraction) improved the microstructure stability due to the restraint of harmful Y-NiMo phase formation during the thermal exposure at the high temperature above 1 000℃.And the reason may be that the addition of Ru increased the degree of Mo supersaturation in bothγandγ’ phases,and hence suppressed the precipitation of Y-NiMo *** results of stress rupture tests under the testing condition of 1100℃,120 MPa showed that the addition of 2% Ru in the alloy improved the stress rupture lives significantly for thermal exposed *** improvement of the stress rupture properties may be attributed to the restraint of Y-NiMo phase precipitation and growth by the addition of the proper amount Ru.

关键词： Ni3Al microstructure stability Ru Y-NiMo phase stress rupture

Directional solidification behavior of turbine blades in DZ125 alloy:design of blade numbers on assembly

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Rare Metals 2021年第5期40卷 1134-1144页

作者： Yong Shang Yan-ling Pei Sheng-Kai Gong Yi Ru Yuan-Chao Yu Ru-Hao Zhou shu-suo li Hui-Bin Xu School of Materials Science and Engineering Beihang UniversityBeijing 100191China

The influence of blades assembly,i.e.,the blade number on the solidification process,heat exchange and grain structure on a directionally solidified Ni-based superalloy DZ125 was investigated by combining the experimental and simulation *** casting process was simulated thermodynamically by ProCAST software,where the interface heat transfer coefficient was precisely determined by a measurement with *** is a good agreement between experimental and simulation *** was interestingly found that with the number of blades increasing from 6 to 10,due to the decrease in radiation absorption efficiency,the maximum temperature and the heating rate decrease in the mold,during the preheat *** the withdrawal procedure,increased assembly numbers reduce the radiation exchange from mold to the enclosure,resulting in the decrease in cooling rate and temperature gradient of the *** the end of withdrawal,the slower cooling rate of the outside balances the temperature distribution of internal and external surfaces on the rabbet of blade.

关键词： Directional solidification Superalloy ProCAST Interfacial heat transfer coefficient

Effect of trace Zn,P and Mg additions on microstructure and mechanical properties of Nb-Si-Ti alloys

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Progress in Natural Science:Materials International 2011年第2期21卷 139-145页

作者： Mei-ling WU,shu-suo li,li-wu JIANG,Sheng-kai GONG,Ya-fang HAN School of Materials Science and Engineering,Beihang University,Beijing 100191,China School of Materials Science and Engineering Beihang University Beijing 100191 China

The effects of Zn,P and Mg additions on the microstructure and mechanical properties of Nb-22Ti-3Si alloys were studied. The phases of Nbss and Nb3Si presented in Nb-22Ti-3Si(AC1),Nb-22Ti-3Si-0.2Zn(AC2) and Nb-22Ti-3Si-0.2Mg alloys(AC3). The Nb-22Ti-3Si-0.2P(AC4) alloy consisted of Nbss,Nb3Si network and eutectic cell of Nbss/α-*** the addition of Zn,the Nb3Si network was broken and the volume fraction of Nbss increased from 92%to 96%.The values of fracture toughness of the alloy AC2 at ambient temperature increased from 22,58 MPa·m1/2to 26.41 MPa·m1/*** values of compressive strength for the Zn-added alloy at ambient temperature and 1 250℃increased from 1 525.10 MPa to 1 652.44 MPa,and from 268.52 MPa to 284.18 MPa,*** with the alloy AC1,the addition of P promoted the formation ofα-Nb5Si phase but the values of fracture toughness and compressive strength of alloy at room temperature and 1 250℃*** contrast,the addition of Mg improved the compressive strength at ambient temperature and 1250℃from 1 525.10 MPa to 1 618.08 MPa and from 268.52 MPa to 348.28 MPa,*** relationship between the microstructure and the mechanical properties was discussed.

关键词： Nb-Si-Ti alloy Zn addition P Mg microstructure mechanical property

Single-stage Posterior Spondylectomy, Circumferential Decompression and Reconstruction Using Mesh Cage for Spinal Tumors

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Chinese Medical Sciences Journal 2009年第3期24卷 172-177页

作者： Yong Zhu Hong Zhao Giu-xing Qiu Jian-guo Zhang Ye Tian shu-gang li suo-mao Yuan Department of Orthopedics Peking Union Medical College Hospital Chinese Academy of Medical Sciences ＆ Peking Union Medical College Beijing 100730 China

Objective To explore the feasibility and clinical results of circumferential decompression and three column reconstruction through single-stage posterior transpedicular approach for spinal tumor treatment. Methods Totally, 24 patients with spinal tumor underwent tumor resection and spinal reconstruc tion through single-stage posterior transpedicular approach. Preoperatively, according to the Frankel classification, 12 patients were grade E, 9 grade D, and 3 grade C. Anterior column was reconstructed with non-expandable titanium cages. Posterior segmental instrumentation was used to maintain the stability of spine in all cases. Anterior and posterolateral fusion was performed with autograft and allogenic bone. The following data were followed up in these patients: deformity angle, local recurrence, neurological function, and spinal bony fusion. Results The average operating time and blood loss was 5.6 hours and 3 400 ml respectively. No intraoperative and postoperative complications were observed in this group. Postoperatively, 21 patients were Frankel grade E, 2 grade D, and 1 grade C. Four patients reported significant functional restoration and twenty patients reported complete resolution of pain. At follow-up (range, 6-42 months), implant failure or recurrent neurological symptoms was not found. Conclusions The tumor resection and spinal reconstruction through single-stage posterior transpedicular approach is a safe and effective technique for the treatment of spinal tumor. It can fully decompress the neurological structures, correct the kyphosis, and achieve early weight-bearing. This technique can improve life quality for the patients with spinal tumor.

关键词： spinal tumor vertebrectomy spinal reconstruction