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Rare Metals 2023年第11期42卷 3859-3869页

作者： Cheng-Yang Jiang Min Feng Chun-Tang Yu Ze-Bin Bao Sheng-Long Zhu Fu-Hui Wang Shenyang National Laboratory for Materials Science Northeastern UniversityShenyang110819China Institute of Metal Research Chinese Academy of SciencesShenyang110016China

Two thermal barrier coating(TBC)systems comprising NiCoCrAlY bond coat onto a second-generation Ni-based single crystal superalloy and nano structured4 mol%Y_(2)O_(3)-stabilized ZrO_(2)(4YSZ)and conventional yttria-stabilized zirconia(YSZ)top coats upwardly were deposited by approaches of arc ion plating(AIP)and air plasma spray(APS).As indicted by the experimental results,the 4YSZ TBCs exhibited superior thermal cycling resistance compared with conventional YSZ TBCs at 1100℃.The 4YSZ top coat exhibited higher toughness due to its intrinsic property of nanocrystalline structure,homogeneously distributed and diverse directions of pores and preexisted cracks.The cracks and spallation in 4YSZ TBCs occurred at the interface of top coat and thermally grown oxide(TGO)layer.Instead,the crack initiation and propagation started along the lamellar interface in the top coat of conventional YSZ TBCs,leading to the rapid crack bridging and subsequent spalling of top coat.Additionally,before and after oxidation,the 4YSZ top coat showed higher hardness compared to conventional YSZ top coat.Degradation mechanism and distribution of residual stress in TGO for the 4YSZ TBCs were investigated in the current study.

关键词： TBC Nanocrystalline TGO thermal cycling Toughness

Composition optimization, high-temperature stability, and thermal cycling performance of Sc-doped Gd_(2)Zr_(2)O_(7) thermal barrier coatings: Theoretical and experimental studies

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Journal of Advanced Ceramics 2022年第3期11卷 454-469页

作者： Lei GUO Bowen LI Yuxian CHENG Lu WANG School of Materials Science and Engineering Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Advanced Joining Technology Key Lab of Advanced Ceramics and Machining Technology of Ministry of EducationTianjin 300072China AECC Shenyang Liming Aero-Engine Co. Ltd.Shenyang 110043China

Sc was doped into Gd_(2)Zr_(2)O_(7) for expanding the potential for thermal barrier coating (TBC) applications. The solid solution mechanism of Sc in the Gd_(2)Zr_(2)O_(7) lattice, and the mechanical and thermophysical properties of the doped Gd_(2)Zr_(2)O_(7) were systematically studied by the first-principles method, based on which the Sc doping content was optimized. Additionally, Sc-doped Gd_(2)Zr_(2)O_(7) TBCs with the optimized composition were prepared by air plasma spraying using YSZ as a bottom ceramic coating (Gd-Sc/YSZ TBCs), and their sintering behavior and thermal cycling performance were examined. Results revealed that at low Sc doping levels, Sc has a large tendency to occupy the lattice interstitial sites, and when the doping content is above 11.11 at%, Sc substituting for Gd in the lattice becomes dominant. Among the doped Gd_(2)Zr_(2)O_(7), the composition with 16.67 at% Sc content has the lowest Pugh’s indicator (G/B) and the highest Poisson ratio (σ) indicative of the highest toughness, and the decreasing trends of Debye temperature and thermal conductivity slow down at this composition. By considering the mechanical and thermophysical properties comprehensively, the Sc doping content was optimized to be 16.67 at%. The fabricated Gd-Sc coatings remain phase and structural stability after sintering at 1400 ℃ for 100 h. Gd-Sc/YSZ TBCs exhibit excellent thermal shock resistance, which is related to the good thermal match between Gd-Sc and YSZ coatings, and the buffering effect of the YSZ coating during thermal cycling. These results revealed that Sc-doped Gd_(2)Zr_(2)O_(7) has a high potential for TBC applications, especially for the composition with 16.67 at% Sc content.

关键词： thermal barrier coating(TBC) first-principles calculation solid solution mechanism high-temperature stability thermal cycling

thermal cycling performance of La_(2)Ce_(2)O_(7)/YSZ TBCs with Pt/Dy co-doped NiAl bond coat on single crystal superalloy

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Rare Metals 2021年第9期40卷 2568-2578页

作者： Zi-Min Zhou Hui Peng Lei Zheng Hong-Bo Guo Sheng-Kai Gong School of Materials Science and Engineering Beihang UniversityBeijing 100191China Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology Beihang UniversityBeijing 100191China Key Laboratory of Aerospace Materials and Performance(Ministry of Education) Beihang UniversityBeijing 100191China

thermal barrier coatings(TBCs) consisting ofLa_(2)Ce_(2)O_(7)(LCO) and Y_(2)O_(3)-stabilized-ZrO_(2)(YSZ) doubleceramic layer and Dy/Pt co-doped NiAl bond coat were produced by electron beam physical vapor deposition(EBPVD). thermal cyclic performance of the TBCs was evaluated by flame shock testing at 1300 ℃. For comparison, the TBCs with a undoped NiAl bond coat were also studied. The microstructural evolution and failure mechanisms of the above TBCs during thermal cycling were investigated. Spallation failure of the TBCs with the undoped bond coat occurs after around 500 cycles by cracking at the interface between YSZ ceramic layer and thermally grown oxides(TGO) layer. The TBCs with Pt/Dy modified bond coat reveal improved interface bonding even after 1200 thermal cycles, whereas some delamination cracks are presented in the LCO layer. On the other hand,the Pt/Dy modified bond coat effectively suppresses the formation of the needle-like topologically closed packed phases(TCP) in the single crystal superalloy.

关键词： thermal barrier coatings NiAl bond coat Pt/Dy co-doping Electron beam physical vapor deposition thermal cycling Interdiffusion

Microstructure,wetting property of Sn-Ag-Cu-Bi-xCe solder and IMC growth at solder/Cu interface during thermal cycling

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Rare Metals 2021年第3期40卷 714-719页

作者： Yuan Wang Xiu-Chen Zhao Ying Liu Yong Wang Dong-Mei Li School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Center of Packaging and Testing Beijing Microelectronics Technology InstituteBeijing 100076China

The effects of adding small amounts of cerium(Ce) to Sn-3.3 Ag-0.2 Cu-4.7 Bi solder on microstructure,wettability characteristic,interfacial morphology and the growth of interfacial intermetallic compound(IMC) during thermal cycling were investigated by optical microscopy(OM),scanning electron microscopy(SEM) and solderability tester.It is found that the p-Sn phase,Ag_(3)Sn phase and Cu6 Sn5 phase in the solder are refined and the wetting force increases.Ce is an active element;it more easily accumulates at the solder/flux interface in the molten state,which decreases the interfacial surface energy and reduces the driving force for IMC formation on Cu substrate;therefore,the thickness of IMC at the solder/Cu interface decreases when appropriate Ce was added into the solder.Moreover,the Ce-containing solders have lower growth rate of interfacial IMC than solders without Ce during the thermal cycling between-55 and 125℃.When the Ce content is 0.03 wt% in the Sn-3.3 Ag-0.2 Cu-4.7 Bi solder,the solder has the best wettability and the minimum growth rate of interfacial IMC layer.

关键词： Lead-free solder Rare earth element Microstructure Wettability Intermetallic compound thermal cycling

Microstructural Evolution and Cracking of Pb-free Ball Grid Array Assemblies under thermal cycling

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Journal of Materials Science & Technology 2007年第1期23卷 85-91页

作者： Wei WANG Zhongguang WANG Aiping XIAN Jianku SHANG Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA

Two kinds of CBGA （ceramic ball grid array） assemblies were made by reflow soldering process using two different Pb-free solders. Microstructural evolution and cracks induced by thermal cycling in CBGA assemblies were examined by scanning electron microscopy （SEM） and finite element method （FEM）. Before thermal cycling, intermetallic compounds （IMCs） Cu6Sn5 and Ag3Sn were observed at the solder interface between Cu and Ag metallizations, respectively. After thermal cycling, another IMC Cu3Sn was observed near the Cu pad in both two assemblies and the layers of Cu6Sn5 and Ag3Sn became thicker. As a result of thermal cycling, cyclic stress and strain were accumulated in the solder joint leading to fatigue cracking. Both experiments and FEM revealed that cracks preferred to initiate at the corner of each solder joint. Multi-modes of the crack propagation were found in the two assemblies. Based on Coffin-Manson equation, the thermal fatigue life was calculated and the predicted life showed good agreement with the experimental results.

关键词： CBGA thermal cycling FEM Assembly Cracking

Mechanical property and structural changes by thermal cycling in phase-separated metallic glasses

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Journal of Materials Science & Technology 2021年第19期78卷 144-154页

作者： Y.Tang H.B.Xiao X.D.Wang Q.P.Cao D.X.Zhang J.Z.Jiang International Center for New-Structured Materials(ICNSM) Laboratory of New-Structured MaterialsState Key Laboratory of Silicon Materialsand School of Materials Science and EngineeringZhejiang UniversityHangzhou310027China State Key Laboratory of Modem Optical Instrumentation Zhejiang UniversityHangzhou.310027China

Nondestructive cryogenically thermal cycling has been a simple but effective treatment to enhance mechanical properties of glassy materials.However,how the structural heterogeneities on nanometer scales are affected by thermal cycling is still an issue.Here,we report the response of spatial heterogeneities in three selected Ti_(41)Zr_(25)Be_(28)Fe_(6),Zr_(56)Co_(14)Cu_(14)Al_(16)and Zr_(42)Y_(14)Co_(22)Al_(22)(at.%)metallic glasses(MGs)with different compositions to the thermal cycling,which show significantly different structure and properties after the same treatments and could be ascribed to the joint contribution of relaxation and rejuvenation induced by thermal cycling.The rejuvenation is initially prevailed in a Zr-Y-containing MG,whereas the relaxation is dominant in a Cu-Co-containing MG,both eventually entering into a dynamic equilibrium state.By employing nanometer-scale structural models,the intrinsic correlation between the spatial heterogeneity and thermal cycling is proposed.The discovery could provide the fundamental understanding of the role of spatial heterogeneity in influencing the macroscopic properties of MGs via thermal cycling and help design high-performance glassy materials by tailoring their atomic structures with suitable thermal treatments.

关键词： thermal cycling Metallic glass Spatial heterogeneity Relaxation Rejuvenation

Effect of thermal cycling on Properties and Microstructure of SnAgCuCe Soldered Joints in QFP Devices

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 561-566页

作者： ZHANG Liang XUE Songbai GAO Lili ZENG Guang YU Shenglin SHENG Zhong College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China School of Mechanical ＆ Electrical Engineering Xuzhou Normal University Xuzhou 221116 China The 14th Research Institute China Electronics Technology Group Corporation Nanjing 210013 China

Increasing global concern about the environment is bringing regulatory （European directives） and consumer （＂green products＂） pressure on the electronics industry in Europe and Japan to reduce or completely eliminate the use of lead （Pb） in products. Among all lead-free solder alloys, SnAgCu solder system, which has better thermo-mechanical properties compared with those of SnPb solder, is proven to be one of the promising candidates for electronic assembly. Previous work also revealed that adding a small amount of rare earth Ce into SnAgCu solder can visibly improve the properties and inhibit the excessive growth of the intermetallic compound layer. thermal fatigue properties of SnAgCuCe soldered joints in QFP devices under thermal conditions have been investigated by finite element method and experiments. Based on creep model of low stress and high stress, corresponding creep subroutine was established for simulating the stress and strain response of SnAgCuCe soldered joint from -55 ℃ to 125 ℃, and fatigue life was calculated using creep fatigue life prediction equation. Moreover, thermal cycling experiments were conducted, the experimental results were found to be close to the simulated results. In addition, the tensile force of SnAgCuCe soldered joints decreased with increasing number of thermal cycles, and the fracture mechanism transformed from toughness fracture to brittle intergranular fracture. Moreover the tensile force changes and fracture microstructure evolution could benefit the quantitative evaluations of the mechanical performances of lead-free soldered joints under thermal cycling loadings.

关键词： finite element method creep equation thermal cycling fatigue life

Study on the thermal Expansion and thermal cycling of AlNp/Al Composites

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Journal of Materials Science & Technology 2002年第1期18卷 62-65页

作者： Qiang ZHANG, Gaohui WU, Dongli SUN and Bofeng LUANSchool of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China [ Manuscript received January 8, 2001, in revised form April 13, 2001] Sch. of Mat. Sci. and Eng. Harbin Inst. of Technol. Harbin 150001 China

The AIN particle reinforced aluminum matrix composites with 50% volume fraction were fabricated by squeeze-casting technology. The thermal expansion behavior and its response to thermal cycling were studied between 20℃ and 400℃. Compared with four theoretical models, the measured CTEs of the composite lie within the elastic bounds derived by Schapery’s analysis. Schapery’s model and Kerner’s model agree well with the CTEs of the composites at lower temperature and elevated temperature, respectively. Strain hysteresis was observed between heating and cooling curves during cycling. This was attributed primarily to the anelastic behavior of the matrix induced by matrix residual stresses.

关键词： AIN Aluminum matrix composite thermal expansion thermal cycling

Oxidation and thermal Fatigue Behaviors of Two Type Hot Work Steels During thermal cycling

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Journal of Iron and Steel Research(International) 2013年第11期20卷 90-97页

作者： MIN Yong-an Bergstrm Jens WU Xiao-chun XU Luo-ping School of Materials Science and Engineering Shanghai University Department of Materials Engineering Karlstad University

thermal fatigue test has been carried out on widely used hot work steel 4Cr5MoSiV1 and a low alloyed steel 3Cr3MoV in temperature range of 200 to 700 ℃. Tempering resistance, as well as high temperature hardness/ strength of steel specimens, works as a dominating material parameter on thermal fatigue resistance. During the heating period, high hardness can depress the inelastic deformation. This deformation is the origination of tensile stress, which acts as the driving [orce o{ heat checking during the cooling period. The cyclic strain-oxidation interac- tion can speed up the damage on surface defects, which plays an obvious role in initiation of thermal cracks. On 4CrSMoSiV1 steel specimens, borders between the matrix and inclusions such as titanium compounds, or lager car- bides such as primary carbides, are focused by strain and attacked by oxidation, and are main initiating places of cracks. While on 3Cr3MoV steel specimens, larger strain causes plastic deformation concentrating around grain boundaries. Then the following oxidation accelerates this grain boundary damage and creates cracks.

关键词： thermal fatigue hot work steel oxidation heat checking thermal cycling tempering resistance

Life Prediction of Ball Grid Array Soldered Joints under thermal cycling Loading by Fracture Mechanics Method

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Journal of Materials Science & Technology 2001年第1期17卷 165-166页

作者： Hongyuan FANG Li WANG Yiyu QIAN National Key Laboratory of Advanced Welding Production Technology Harbin Institute of TechnologyHarbin 150001China

Fatigue crack propagation life of ball grid array (BGA) soldered joints during thermal cycling loading was investigated by fracture mechanics approach using finite element analysis. The relationships between the strain energy release rate (G) and crack size (a), thermal cycle numbers (N) can be derived.’ Based on the relationships, fatigue life of the soldered joints was determined. The results showed that crack propagation life was higher than crack initiation life. Therefore, it appears that it is more appropriate to predict the fatigue life of soldered joints using the fracture mechanics method.

关键词： Fracture Mechanics thermal cycling Soldered Joints soldered joints fracture mechanics crack propagation strain energy release rate fatigue life finite element analysis crack initiation thermal cycling ball grid array