Interface analysis of 7B52 Al alloy laminated composite fabricated by hot-roll bonding

The bonding interface of 7B52 Al alloy laminated composite （ALC） fabricated by hot rolling was investigated using optical microscopy （OM）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, ultrasonic flaw detection （UFD）, and bonding strength tests. The results show that metallurgical bonding is achieved at the interface after composite rolling. The TEM analysis and tensile tests indicate that the 7B52 ALC plate combines high strength of the hard individual layer and good toughness of the soft individual layer. However, UFD technology and SEM analysis prove that the defects （thick oxide films, acid washed residues, air, oil and coarse particles） existing in the bonding interface are harmful to the bonding strength. To sum up, the composite roiling process is suitable for 7B52 ALC plate, and the content and size of the defects should be controlled strictly. Advanced surface treatment of each individual layer would be beneficial to further improve the bonding quality.

Force-displacement characteristics of simply supported beam laminated with shape memory alloys

As a preliminary step in the nonlinear design of shape memory alloy（SMA） composite structures,the force-displacement characteristics of the SMA layer are studied.The bilinear hysteretic model is adopted to describe the constitutive relationship of SMA material.Under the assumption that there is no point of SMA layer finishing martensitic phase transformation during the loading and unloading process,the generalized restoring force generated by SMA layer is deduced for the case that the simply supported beam vibrates in its first mode.The generalized force is expressed as piecewise-nonlinear hysteretic function of the beam transverse displacement.Furthermore the energy dissipated by SMA layer during one period is obtained by integration,then its dependencies are discussed on the vibration amplitude and the SMA＇s strain（Ms-Strain） value at the beginning of martensitic phase transformation.It is shown that SMA＇s energy dissipating capacity is proportional to the stiffness difference of bilinear model and nonlinearly dependent on Ms-Strain.The increasing rate of the dissipating capacity gradually reduces with the amplitude increasing.The condition corresponding to the maximum dissipating capacity is deduced for given value of the vibration amplitude.The obtained results are helpful for designing beams laminated with shape memory alloys.

Oxidation Resistance of Fe-13Cr Alloy with Micro-Laminated (ZrO_2-Y_2O_3)/(Al_2O_3-Y_2O_3) Films

The micro-laminated （ZrO2-Y2O3）/（Al2O3-Y2O3） composite films were prepared on the surface of Fe-13Cr alloy by an electrochemical process and a sintering process alternately. High-resolution field emission scanning electron microscopy （FE-SEM） was used to characterize the laminated films, indicating that the micro-laminated （ZrO2-Y2O3）] （Al2O3-Y2O3） films have nano-structures. SEM, EDS and mass gain measurement were adopted to study the oxidation resistance of films on Fe-13Cr alloy. It is proved that such micro-laminated films are more effective than ZrO2-Y2O3 or Al2O3-Y2O3 films to resist the oxidation of the alloy, and the oxidation resistance is increased with increasing layers in micro-laminated films. These beneficial effects can be contributed to the mechanism, by which such micro-laminated （ZrOE- YEO3）/（Al2O3-Y2O3） composite film combines all the beneficial effects and overcomes all the disadvantages of both ZrOE- Y2O3 film and Al2O3-Y2O3 film during oxidation of alloy.

Internal friction peak and damping mechanism in high damping aluminium alloy laminate

A new aluminium alloy laminate characterized by high damping, corrosion resistance and weldablity was developed. The laminate designed for required aforesaid functions was actually a composite material, which was made of two anti corrosive layers (Al), two damping layers (ZnAl alloy) and one reinforcing layer (AlMg alloy) by hot rolling. The damping characteristics were studied and it was found that there was an internal friction peak at about 50 ℃ on internal fraction vs temperature curve for the laminate. For this reason, the activation energy of the peak was calculated. The origin and damping mechanism for this peak was researched by means of SEM, TEM, X ray and DSC. It is considered that the peak is caused by the interaction between dislocations and point defects in damping layers (AlZn alloy). i.e. by the movement of dislocations dragging point defects under the action of thermal activation. The laminate is remained at room temperature for a long time, it will weaken or even disappear with the restoration of the crystal microstructure and the reduction of the dislocation density in the ZnAl alloy layers. The mechanism of the peak is in conformity with that of the dislocation induced damping. [

Aero-Elastic Flutter Characteristics of Laminated Composite Panel Embedded with Shape Memory Alloy Wires

The effects of shape memory alloy( SMA) wires on the natural frequency,flutter boundary and amplitude of limit cycle oscillation( LCO) of a laminated composite panel are investigated. The classical plate theory as well as von-Karman strain-displacement relation are used to formulate the nonlinear dynamic model of the smart laminated panel. The aerodynamic loadings are simulated by the third order piston theory. The thermomechanical behavior of SMA wires is estimated according to one-dimensional Brinson SMA model. The effects of SMA wires temperature,pre-strain,volume fraction and orientation on flutter boundary and amplitude of LCO of the panel are analyzed in detail.

Corrosion damage evolution and mechanical properties of carbon fiber reinforced aluminum laminate

Fiber metal laminates(FMLs),a kind of lightweight material with excellent comprehensive performance,have been successfully applied in aerospace.FMLs reinforced with carbon fiber have better mechanical properties than those with glass or aramid fiber.However,carbon fiber binding metal may lead to galvanic corrosion which limits its application.In this paper,electrochemical methods,optical microscope and scanning electron microscope were used to analyze the corrosion evolution of carbon fiber reinforced aluminum laminate(CARALL)in corrosive environment and explore anti-corrosion ways to protect CARALL.The results show that the connection between carbon fiber and aluminum alloy changes electric potential,causing galvanic corrosion.The galvanic corrosion will obviously accelerate CARALL corroded in solution,leading to a 72.1%decrease in interlaminar shear strength,and the crevice corrosion has a greater impact on CARALL resulting in delamination.The reduction of interlaminar shear strength has a similar linear relationship with the corrosion time.In addition,the adhesive layers between carbon fiber and aluminum alloy cannot protect CARALL,while side edge protection can effectively slow down corrosion rate.Therefore,the exposed edges should be coated with anti-corrosion painting.CARALL has the potential to be used for aerospace components.

Bonding interface zone of Mg-Gd-Y/Mg-Zn-Gd laminated composite fabricated by equal channel angular extrusion

In order to improve the mechanical properties and corrosion resistance of Mg alloys,the equal channel angular extrusion (ECAE)was employed to fabricate the Mg-5Gd-5Y/Mg-2Zn-1Gd(GW55/ZG21)laminated composites.After fabrication and annealing treatment,the microstructural evolution,phase constitution,microhardness,and bonding strength were investigated on the bonding interface zone of GW55/ZG21 laminated composites.The bonding interface zone of GW55/ZG21 laminated composites comprises a lot of Mg3(Y,Gd)2Zn3 particles along the bonding interface,some rod Mg24(Y,Gd)5 phases on GW55 side,and a precipitation free zone(PFZ)on ZG21 side.After annealing treatment,Mg3(Y,Gd)2Zn3 particles along the bonding interface increase, rod Mg24(Y,Gd)5 phases on GW55 side decrease,and PFZ is broadened.Meanwhile,the hardness on the bonding interface zone decreases and the bonding strength increases from 126 MPa to 162 MPa.

ANALYSIS AND MEASUREMENT ONRESIDUAL STRESS OF ARAMIDALUMINIUMLAMINATE

Residual stresses of the ordinarily cured and pre-stressed unidirectionallaminate are analyzed quantitatively. In order to examine the analyzing formulations,strain gages were embedded in the uni-directional aramid aluminium laminates (ordi-narily cured and pre-stressed) to determine the residual stresses in the aluminiumlayers. The calculated residual stresses are in good agreement with the experimental val-ues in the longitudinal direction. Therefore, the work in this paper can be used to calcu-late, determine and design the longitudinal residual stresses according to the manufac-ture and application demands.

Electron Beam-Physical Vapor Deposited TiAl-based Laminated Composite Sheet with Nb Layer Toughening

The TiAl-based laminated composite sheet of 150 mm × 100 mm × 0.2 mm, with 24 TiAl layers and 23 Nb layers laid alternately one on another, was successfully fabricated using the electron beam-physical vapor deposition （EB-PVD） method. The microstructure and properties of the sheet were investigated on an atomic force microscope （AFM）, a scanning electron microscope （SEM） and a tensile testing machine. The results indicate that the evenly distributed Nb layers are well joined with the TiAl layers, and the interfaces between layers are transparent, and every interlayer spacing is of about 8μm. The fractures appear to be a mixture of intergranular fractures and somewhat ductile quasi-cleavage ones. Despite its slight influence on ultimate tensile strength, the inserts of Nb layers efficiently increase the room temperature ductility of TiAl-based alloys due to the crack deflection effect.

Mechanical Properties of Laminated Aluminum-Based Plates with Gradient Interface

Two laminated composites, 2024/3003 and 7075/6009 aluminum alloys were prepared by double-stream-pouring continuous casting (DSPCC) followed by plastic deformation and heat treatment. The interface characteristics between the external and internal layers of the composites in the as-cast and plastic deformation conditions were analyzed. The results show that the macrostructure difference between the external and internal layers of both composite ingots in the as-cast condition can be clearly clarified but the gradient interfaces are not distinct. However, the macro-scale gradient layers can be demonstrated from the hardness distribution in the cross sections of the composite ingots. After plastic deformation, the gradient characteristic of the interface in the laminated composites maintains except for the decrease in the interface thickness. After plastic deformation and T6 heat treatment, the ultimate strength, yield strength and elongation of 2024/3003 composite plate are 2.35, 3.10 and 0.9 times of that of 3003 aluminum alloy, respectively. The ultimate strength and yield strength of 7075/6009 composite plate increase 47 % and 82 % of that of 6009 aluminum alloy, respectively and the elongation of the composite is still as high as 15.3 %.

Fabrication, microstructure and properties of electron beam-physical vapor deposited TiAl sheet and TiAl/Nb laminated composites

The TiAl-based alloys sheet with 150 mm×100 mm×0.4 mm and the TiAl/Nb laminated composites with 150 mm×100 mm×0.2 mm were fabricated by using electron beam-physical vapor deposition(EB-PVD) method, respectively. The microstructure and properties of the sheet were investigated by AFM, SEM and EDS. The results show that the TiAl based alloys sheet has a good surface quality, and its microstructure is columnar crystal. The component of the alloys indicates a regular and periodical gradient change which leads to the spontaneous delamination along the normal direction of substrate. In the TiAl/Nb laminated composites alternating overlaid by TiAl of 24 layers and Nb of 23 layers, the interface of each layer evenly distributed throughout the cross-section is transparent, and the interlayer spacing is about 8μm. The component of TiAl layers also changes regularly along the normal direction of substrate, but no delamination phenomenon is found. The TiAl/Nb laminated composites have better ductility than the TiAl-based alloys sheet.

Crystallization microstructure of Mg_(65)Cu_(25)Y_(10) bulk amorphous alloy

Mg65Cu25Y10 bulk amorphous alloy specimens prepared by conventional copper mould method were heated at 200 °C for different time and the phase contents as well as microstructure were studied.The XRD results show that the crystallization of Mg65Cu25Y10 bulk amorphous alloy specimen becomes complete as the treating time increases and Mg2Cu,Mg24Y5 and HCP-Mg crystalline phases are found.Snowflake-like morphology is found in different specimens through SEM observation.The EDS patterns show that the composition of the snowflake-like structure is close to that of the as-cast alloy.Laminated structures are observed from the TEM images of the snowflake-like structure.From the electron diffraction patterns,it is seen that the snowflake-like structure is the combination of Mg24Y5 and amorphous matrix.The FCC-Mg phase in the matrix transforms into HCP-Mg during the heat-treating process.

Texture evaluation in AZ31/AZ31 multilayer and AZ31/AA5068 laminar composite during accumulative roll bonding

This article presents the texture development of magnesium AZ31 alloy in the accumulative roll bonded(ARB) AZ31/AZ31 multilayer and AZ31/AA5086 laminate composite.The comparative study demonstrates that the texture evolution in AZ31 in a multilayer system is strongly influenced by the interfaces.A typical basal texture of AZ31 has been observed in AZ31/AZ31 multilayer with texture intensity increased with the rolling deformation.Presence of AZ31/AA5086 interface in the laminate composite leads to a tilted basal texture along the rolling direction(RD) in AZ31 alloy.The texture intensity of composite increased initially with rolling reduction and weakened at the higher rolling strain.Weakening of texture in AZ31 during the laminate processing at higher strain has been attributed to the development of wavy interfaces in AZ31/AA5086 laminate.

Thermo-mechanical Behaviors of Functionally Graded Shape Memory Alloy Timoshenko Composite Beams

This paper focuses on the thermo-mechanical behaviors of functionally graded(FG)shape memory alloy(SMA)composite beams based on Timoshenko beam theory.The volume fraction of SMA fiber is graded in the thickness of beam according to a power-law function and the equivalent parameters are formulated.The governing differential equations,which can be solved by direct integration,are established by employing the composite laminated plate theory.The influences of FG parameter,ambient temperature and SMA fiber laying angle on the thermo-mechanical behaviors are numerically simulated and discussed under different boundary conditions.Results indicate that the neutral plane does not coincide with the middle plane of the composite beam and the distribution of martensite is asymmetric along the thickness.Both the increments of the functionally graded parameter and ambient temperature make the composite beam become stiffer.However,the influence of the SMA fiber laying angle can be negligent.This work can provide the theoretical basis for the design and application of FG SMA structures.

热处理对1060/7N01/1060轧制复合板显微组织及力学性能的影响

利用475℃单道次热轧的方式制备界面结合良好的1060/7N01/1060层状复合板。通过扫描电子显微镜、透射电子显微镜及电子背散射衍射结合硬度和拉伸实验研究层厚比对热轧复合板显微组织和力学性能的影响。此外,对比研究冷轧前热处理(固溶处理及峰值时效)对冷轧复合板显微组织和力学性能的影响。结果表明,层厚比对热轧复合板各层显微组织特征影响不大,其力学性能与混合法则理论预测结果一致。相比而言,额外的热处理对冷轧板纯铝层的晶粒尺寸无明显影响,却有助于细化7N01层的晶粒尺寸及弥散、细小析出物的形成,使其具有更显著的细晶强化、析出强化及位错强化效应。

钛合金扩散连接技术及其层合结构疲劳裂纹扩展研究进展

本文主要对钛合金的扩散连接及层合结构疲劳裂纹扩展行为的研究进展进行了综述,总结了扩散连接钛合金界面的微观组织演变和疲劳裂纹扩展特性。首先概述了超塑成形/扩散连接技术的应用背景和优势,以及提高钛合金扩散连接界面质量的辅助技术(如添加中间层、热氢处理、脉冲电流加热和表面改性)。从钛合金扩散连接和钛合金与其他合金扩散连接两方面综述了界面组织和力学性能,指出组织演变严重依赖界面处合金元素种类和元素相互扩散能力。扩散连接技术可用来制备同种和异种合金的层合结构,且可灵活控制界面焊合与未焊合区域的形状与分布。最后,简述了同种或异种钛合金扩散连接层合结构可降低疲劳裂纹扩展速率,从而优化钛合金构件的疲劳损伤容限性能。

热压工艺参数对TA2/CF/PEEK层板弯曲性能的影响

以TA2箔、碳纤维和PEEK材料体系为基础,探索钛箔-碳纤维布-PEEK薄片直接复合的热压法制备工艺。在对初始材料进行超声清洗除油、砂纸打磨等预处理后,手工铺层并放入自行设计的热压模具,基于不同温度(370和390℃)、压力(0.8、1.6和2.5 MPa)与保压时间(20和40 min)的热压法制备了TA2/CF/PEEK层板。利用三点弯曲实验方法探究了热压工艺参数对层板弯曲性能的影响。结果表明,较佳的热压工艺为:成形温度390℃、热压压力1.6 MPa、保压时间40 min且每侧铺设两片树脂薄膜。在此工艺下制备的TA2/CF/PEEK层板弯曲强度为681.68 MPa,弯曲模量为69.5 GPa。

基于电热耦合分析 SMA-CFRP 复合材料层合板雷击烧蚀损伤

为了研究形状记忆合金(SMA)材料对碳纤维增强聚合物(CFRP)复合材料层合板的雷击损伤防护效果,基于常用的雷击电热耦合模型建立含形状记忆合金丝的层合板的雷击损伤有限元分析模型,与参考结果进行对比以验证模型的合理性,并与传统层合板的雷击损伤进行对比来分析SMA丝的雷击防护作用。此外,分析了不同峰值电流、SMA丝不同数量、嵌入SMA丝区域之间的不同间距和层合板不同铺层顺序等因素对SMA-CFRP层合板烧蚀损伤结果的影响,并分析影响规律。结果表明:SMA对CFRP层合板的雷击损伤防护有显著的效果,其中峰值25 kA雷击电流导致的烧蚀损伤面积降低至无防护层合板的57.43%。此外,SMA丝数量、嵌入SMA丝区域之间的不同间距和层合板的铺层顺序对SMA-CFRP层合板的烧蚀损伤的面积和深度具有较大影响。

层状铝合金复合板钎焊工艺的研究

采取简便改进措施,探索4343/3003层状铝合金复合板在普通箱式炉中的钎焊工艺。结果表明:在普通箱式炉中,用预热的钢块使试样快速升温,同时将热电偶探头与试样表面直接接触进行测温,用木炭覆盖试样表面防止氧化,在这些改进措施实施后,可以获得质量良好的钎焊接头。讨论了钎焊温度、保温时间及载荷压力对钎缝宏观形貌和微观组织的影响,得出结论:在普通箱式炉中,均匀施加1.5 N载荷,在610℃下保温8 min或620℃下保温6 min, 4343/3003层状铝合金复合板钎焊接头质量良好。

Progress on the glassy-crystal laminates:From design,microstructure to deformation and future solutions

The development of new design strategies to create innovative structural materials,refine existing ones,and achieves compatible combinations of strength and plasticity remains a worldwide goal.Promising alloys,such as shape memory alloys(SMAs),bulk metallic glasses(BMGs),high entropy alloys(HEAs),and heterogeneous pure metals such as Cu,have excellent mechanical responses,but they still fall short of meeting all the requirements of structural materials due to specific flaws,such as lack of tensile de-formation for BMGs and low yielding strength for HEAs.To address these shortcomings,proposals such as integrating glassy matrices and crystallized alloys,such as HEAs/SMAs,have been suggested.However,these solutions have unresolved issues,such as the challenging control of B2 phase formation in BMG composites.Recently,glass-crystal(A/C)laminated alloys with alternating layers have been reported to exhibit improved mechanical properties and activated work-hardening behaviors,but they still face press-ing issues such as bonding interfaces and unknown deformation mechanisms.This review focuses on design routes such as the selection of alloy components and processing techniques,exploration of micro-structural evolution and deformation modes with an increase in strain,and future solutions to address pressing and unsolved issues.These prominent advantages include diversified deformation mechanisms,such as deformation twinning,martensitic phase transformation,and precipitation hardening,as well as tuned interactive reactions of shear bands(SBs)near the A/C interfaces.Thus,this review provides a promising pathway to design and develop structural materials in the materials field community.