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Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 165-171页

作者： Dan Chen Jinglong Li Huaxia Zhao Zhejun Tan jiangtao xiong State Key Laboratory of Solidifi cation Processing Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical UniversityXi’an 710072China AVIC Manufacture Technology Institute Beijing 100024China

Friction stir lap welding was conducted on 2 mm + 2 mm sheets of aluminum alloy 2 A12-T4. The plunge depth(PLD) was designed as 2.45–2.58 mm, which was varied in submillimeters as 2.45, 2.50, 2.53, 2.55, and 2.58 mm, and the axial force was recorded in the welding process. The results show that the PLD fluctuation in submillimeters causes significant variation in the axial force and affects the voids(i.e., Void I and Void II), hook, and effective sheet thickness(EST), among which Void I is the main factor that affects the EST. The fracture load–PLD function in the tensile shear test of the joints follows the rule of the EST–PLD function. An optimized PLD is approximately 2.55 mm, at which the EST reaches 1.71 mm, corresponding to a peak fracture load of 11.03 kN. Thus, a PLD of 2.55 mm is suggested with a tolerance of 0.02 mm, corresponding to a fracture load of 9.6–11.0 kN, i.e., within a fluctuation of 12%.

关键词： Submillimeter Plunge depth Mechanical properties Friction stir lap welding

A New Spot Welding Technique for Fuselage

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材料导报 2019年第10期33卷 1595-1596页

作者： CHEN Dan CHAI Peng ZHAO Huaxia xiong jiangtao LI Jinglong State Key Laboratory of Solidification Processing Northwestern Polytechnical University School of Mechanical Engineering Henan University of Engineering AVIC Manufacturing Technology Institute Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University

High strength aluminum alloys(series 2XXX and 7XXX)are kinds of precipitation-hardening alloys,which have been widely applied in manufacturing of fuselage for their high strength-to-weight ratio,good fatigue performance and damage tolerance[1-2].These structures mostly adopt lap *** traditional joining methods include riveting and bolting,which cost weight-increase and *** disadvantages could be overcome by a new joining technique—friction stir spot welding(FSSW)developed from friction stir welding(FSW).However,after wel-ding,FSSW normally leaves the workpiece with a keyhole,which decreases mechanical properties and corrosion resistance of the *** fill the keyhole,refill friction stir spot welding(RFSSW,Refill-FSSW)was invented by GKSS in *** designs a special welding tool for RFSSW,consisting of pin,sleeve and clamping ring,which are precisely assembled with indepen-dent driving systems[3].In a typical RFSSW process,the pin and sleeve move in opposite direction at a given speed ***,the speeds are set inverse proportional to their cross-sectional *** 2011,GKSS performed RFSSW on aluminum alloy and obtained the joint with good ***,RFSSW was highlighted in research,which was expected to apply in fuselage manufacturing and to replace the traditional joining methods.

关键词： High strength aluminum alloys kinds

Microstructure and mechanical properties in the TLP joint of FeCoNiTiAl and Inconel 718 alloys using BNi2 filler

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Journal of Materials Science & Technology 2021年第2期61卷 176-185页

作者： Lin Yuan jiangtao xiong Yajie Du Jin Ren Junmiao Shi Jinglong Li State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical UniversityXi'an 710072China

High entropy alloy(HEA) of Fe Co Ni Ti Al and Inconel 718 superalloy were firstly transient liquid phase(TLP) bonded by BNi2 filler due to the diffusion of Si and B in the filler to the base metals. The effects of bonding time on microstructure evolution and mechanical properties of the TLP joints were *** to the complete isothermal solidification of the joints bonded for 30 min 120 min at 1100°C,no athermally solidified zones(ASZs) formed by eutectic phases were observed in the welded zone. Thus the TLP joints were only composed by the isothermally solidified zone(ISZ) and two diffusion affected zone(DAZ) adjacent to the dissimilar base metals and the negative effect of the ASZ on joint properties can be avoided. In addition, the increase of the bonding time can also make the Ti B2 borides precipitated in the DAZ near HEA and the brittle borides or carbides in the DAZ near IN718 alloy decrease and reduce the possibility of the stress concentration happened in the joints under loading. Therefore, the highest shear strength(632.1 MPa) of the TLP joints was obtained at 1100°C for 120 min, which was higher than that of the joint bonded for 30 min, 404.2 MPa. Furthermore, the extension of the bonding time made the fracture mechanism of the joint be transformed from the intergranular fracture to the transgranular fracture. However, as the brittle borides in the DAZ near IN718 can not be eliminated completely and refining of grains also happened in such region, all the TLP joints fractured inner the DAZ near IN718 alloy.

关键词： FeCoNiTiAl alloy Inconel 718 alloy Microstructure evolution Mechanical properties Fracture mechanism

Interfacial Microstructure Evolution and Mechanical Properties of TC4/MgAl_(2)O_(4)Joints Brazed with Ti-Zr-Cu-Ni Filler Metal

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Acta Metallurgica Sinica(English Letters) 2024年第12期37卷 2057-2067页

作者： Jiafen Song Wei Guo Shiming Xu Ding Hao Yajie Du jiangtao xiong Jinglong Li State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical UniversityXi’an710072China

In the present study,Ti-Zr-Cu-Ni amorphous filler metal was used to braze MgAl_(2)O_(4)ceramic and Ti-6Al-4V(TC4)at 875,900,925,950,975 and 1000℃for 10 *** effects of brazing temperature on interfacial microstructure and mechanical properties of the joints were *** results showed that typical microstructure of the TC4/MgAl_(2)O_(4)joint was solid solution(SS)α-Ti,acicularα-Ti+(Ti,Zr)_(2)(Ni,Cu)layer,metallic glasses and *** the increase in brazing temperature,(Ti,Zr)_(2)(Ni,Cu)layer gradually dispersed at bonding interface,a continuous layer of TiO appears near MgAl_(2)O_(4)*** the increase in brazing temperature,the hard and brittle(Ti,Zr)_(2)(Ni,Cu)layer gradually dispersed,resulting in the maximum shear strength of 39.5 *** high-resolution TEM revealed the presence of amorphous structure,which is composed of Ti,Zr,Cu,Ni and *** values ofδandΔH_(mix)are calculated to be about 8%and−39.82 kJ/mol for the amorphous phase.

关键词： Brazing TC4 titanium alloy MgAl_(2)O_(4) Microstructure High-entropy metallic glasses

Quasi-in-situ Observation of Interfacial Behaviours:Recrystallization and Grain Recombination during Micro-deformed Diffusion Bonding Process

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Acta Metallurgica Sinica(English Letters) 2023年第12期36卷 2031-2044页

作者： Yu Peng Shiwei Li Feng Jin Yipeng Chen Wei Guo jiangtao xiong Jinglong Li State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical UniversityXi'an 710072China

The interfacial behaviours of micro-deformed diffusion bonded joints were systematically *** were two typical bonding interfacial characteristics:“bond line”and migrated grain boundaries.“Bond line”was featured as fine grains and phases on the *** critical temperature of joint characterized by“bond line”was 950℃.The increased temperature 1000℃was a critical temperature which interfacial characteristic“bond line”*** second type was characterized by interfacial migration over 1000℃,in which the bonding interfaces were composed of straight grain boundaries,triple junctions,and protruding and expanding interfacial migrated ***,two different interface migration and joint forming mechanisms were observed with elevated bonding temperature:recrystallization and grain *** first one was the discontinuous dynamic recrystallization mechanism,which was observed in the joints bonded at 950℃and 1000℃.The second mechanism was the grain boundary migration mechanism based on the grain growth mechanism,of which the typical bonding temperature was 1050℃.The joint was bonded under two kinds of grain boundary migration,including strain-induced interface grain boundary migration and interface grain boundary migration at triple junction.

关键词： Diffusion bonding Critical bonding temperature Interfacial microstructure Dynamic recrystallization Grain recombination

Effect of Ti-Hf-Zr-Cu-Ni high entropy alloy addition on laser beam welded joint of Ti2AlNb based intermetallic alloy

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Journal of Materials Science & Technology 2022年第25期120卷 214-226页

作者： Mirza Zahid Hussain jiangtao xiong Jinglong Li Farah Siddique Lin Jie Zhang Yajie Du Xian Rong Zhou State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical UniversityXi’an 710072China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710072China

TiAlNb based intermetallic alloys,a potential competitor for next-generation super alloys,are susceptible to high-temperature embrittlement due to nucleation of a metastable single B2 phase in the fusion zone(FZ)during laser beam welding(LBW).In this study,a high entropy alloy(HEA),Ti-Hf-Zr-Cu-Ni,was self-developed and introduced as an interlayer into laser beam welded joint(LBWJ)of Ti-22 Al-27 Nb to analyze its impact on the evolution of microstructure in the weld zone(WZ)and subsequently on joint *** examination was carried out through electron probe micro analysis(EPMA),electron backscattered diffraction(EBSD)analysis,high-resolution scanning transmission electron microscopy(HRSTEM)comprising bright field(BF),selective area electron diffraction(SAED)and high angle annular dark-field(HAADF)*** of the HEA into FZ of LBWJ triggered heterogenous nucleation during solidification,resultantly,fine-grained B2 with a greater proportion of high angle grain boundaries(HAGBs)was *** of Ti-22 Al-27 Nb LBWJ,prepared with an interlayer of HEA,was composed of planar,cellular,columnar and equiaxed dendritic grains;a solidification mode which was different from that observed in LBWJ prepared without adulteration of the *** impact of heterogenous nucleation during epitaxial solidification on mechanical properties was established through micro vickers hardness mapping and tensile test,conducted at room *** average hardness,343.5 HV,in the FZ of LBWJ prepared with an interlayer of HEA,was compatible with that of base material(BM),345 *** ultimate tensile strength(UTS),1062 MPa,and percentage elongation,11.2%,of the HEA tempered LBWJ were found in close approximation with that of BM,1060 MPa and 13.4%,respectively.A ductile mode of failure was observed during tensile test of the Ti-Hf-Zr-Cu-Ni supplemented LBWJ of Ti-22 Al-27 Nb,while quasi-cleavage mode of fracture was apparent in the joint of Ti-22 Al-27 Nb welded with

关键词： Laser beam welding Ti2Al Nb based intermetallics High entropy alloy Heterogenous nucleation

Microstructure and mechanical properties of transient liquid phase bonding DD5 single-crystal superalloy to CrCoNi-based medium-entropy alloy

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Journal of Materials Science & Technology 2022年第1期96卷 140-150页

作者： Shiwei Li Jinglong Li Junmiao Shi Yu Peng Xuan Peng Xianjun Sun Feng Jin jiangtao xiong Fusheng Zhang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical UniversityXi’an 710072China

This study focuses on the transient liquid phase(TLP)bonding of DD5 single-crystal superalloy to Cr Co Nibased medium-entropy alloy(MEA)using a BNi-2 filler *** microstructure and mechanical properties of the TLP-bonded DD5/MEA joint were evaluated,and the microstructural evolution mechanism was *** formation of the isothermal solidification zone(ISZ)depended on the diffusion of the melting-point depressants(Si and B elements)from the liquid filler into the DD5 and MEA substrates,as well as the dissolution of the *** diffused along theγchannel of DD5 and reacted to form M_(5)B_(3)boride,herein referred to as the diffusion-affected zone(DAZ I).Similarly,the Cr_(5)B_(3)boride precipitated in the Ni-rich MEA matrix adjacent to the MEA substrate(i.e.,DAZ II).Additionally,a coherent orientation of[0]_(BCY)//[011]_(FCC)and(002)_(BCY)//(200)_(FCC)was detected between M_(5)B_(3)boride with a body-centered tetragonal(BCT)structure and the face-centered cubic(FCC)*** performance of the joint was dominated by the properties of the bonding *** the bonding time increased from 20to 80 min,the athermal solidification zone(including eutectic microstructure)was gradually replaced by the ISZ exhibiting excellent plastic deformation capability,and the shear strength of the joint was *** maximum shear strength(752 MPa)was achieved when the eutectic-free joint was bonded at 1050℃ for 80 *** fracture morphology revealed a mixture mode,indicating the initiation of cracks in the DAZ II,mainly propagating in the ISZ,and passing through the DAZ I.

关键词： Microstructure Mechanical properties Transient liquid phase bonding Single-crystal superalloy Medium-entropy alloy

Additive manufacturing of a high-strength ZrC-SiC and TC4 gradient structure based on a combination of laser deposition technique and brazing

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Journal of Materiomics 2021年第4期7卷 766-779页

作者： Qian Wang Junmiao Shi Lixia Zhang jiangtao xiong Jinglong Li Ninshu Ma Jicai Feng Joining and Welding Research Institute Osaka UniversityIbarakiOsaka567-0047Japan State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an710072China Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical UniversityXi’an710072China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin150001China

A ZrC-SiC and TC4 gradient structure(ZTGS)was additively manufactured through the laser deposition technique and brazing *** research results indicated that SiC-reinforced TC4-based gradient layers could be obtained on the TC4 surface by laser ***-SiC and TC4 coated with gradient layers were brazed using an AgCuTi filler to fabricate the *** effects of the gradient structure and brazing parameters on the ZTGS strength were *** an increase in Layer II and Layer III thickness,the ZTGS shear strength *** brazing temperature and holding time affected the ZTGS shear strength by controlling the formation and distribution of the Cu4Ti phase in the brazing *** strengthening mechanism of the ZTGS was revealed by analyzing the residual stress distribution in the *** residual stress was formed in ZrC-SiC adjacent to the TC4 substrate or the deposited gradient layer,which was found to negatively affect the properties of the *** increase in gradient layer thickness reduced the maximum residual stress in ZrC-SiC,and the effect of Layer III on the residual stress was more significant than that of Layer *** calculated residual stress evolution matched the ZTGS property values well,revealing the strengthening mechanism.

关键词： Gradient structure Laser deposition Brazing Residual stress

真空扩散焊热循环对2A14铝合金接头界面演变的影响

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焊接学报 2007年第3期28卷 41-44页

作者：李京龙熊江涛张赋升西北工业大学摩擦焊接陕西省重点实验室西安710072

分别选取500,530,560℃焊接温度,进行2A14铝合金真空扩散焊,保温时间为60 min,焊接压力为4 MPa,真空压力低于3.4×10-3Pa。焊后用扫描电镜(SEM)观察接头的焊合率、界面和母材组织形貌。结果表明,在500℃固溶线以下温度进行2A14铝合金扩... 详细信息

分别选取500,530,560℃焊接温度,进行2A14铝合金真空扩散焊,保温时间为60 min,焊接压力为4 MPa,真空压力低于3.4×10-3Pa。焊后用扫描电镜(SEM)观察接头的焊合率、界面和母材组织形貌。结果表明,在500℃固溶线以下温度进行2A14铝合金扩散焊时,主要是界面微区塑性变形破碎氧化膜,实现局部微量的金属之间连接,焊合率很低。温度继续升高到530℃,超过固溶线温度,但小于Al-Cu共晶温度时,增加了界面CuAl2相结合机理,焊合率有明显提高。焊接温度在Al-Cu共晶温度以上,达到560℃时,CuAl2相完全溶解并在晶界生成共晶液相。该液相挤压、破碎界面氧化膜,并填充界面微孔,焊接接头界面呈正弦波状界面形貌,因而焊合率显著提高。根据这一分析结果,建立了晶界液相生成与界面氧化膜的破碎模型。

关键词：扩散焊 2A14 共晶温度焊合率铝合金

Kinetic limit for incubation period of primary phase produced by the combination reaction between two solid heterogeneous pure metals

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Science China(Technological Sciences) 2008年第12期51卷 2232-2243页

作者： xiong jiangtao1,2,LI JingLong1,ZHANG FuSheng1,LIN Xin2 & HUANG WeiDong2 1 Shaanxi Key Laboratory of Friction Welding Technologies,Northwestern Polytechnical University,Xi’an 710072,China 2 State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an 710072,China Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Xi’an 710072 China State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi’an 710072 China

An irreversible thermodynamics model was constructed to study the combination reaction of two heterogeneous pure metals in diffusion bonding based on the theorem of minimum entropy production and the Curie *** correlation between the irreversible reaction and diffusion was discussed,which provided the kinetic inevitability of an incubation period of a primary *** analytical descriptions of the incubation period and the kinetically critical grain size of the primary phase were *** of the experimental results of Al/Mo interfacial reaction with the calculations indicated that the performed theoretical analysis was reliable.

关键词： incubation period primary phase interfacial reaction irreversible thermodynamics