Search

Atomic oxygen in the low Earth orbit (LEO) environment is highly oxidizing. Due to the high flight speed of spacecraft, the relative kinetic energy of high-flux atomic oxygen bombarding the spacecraft surface can reach up to about 5 eV. Therefore, atomic oxygen is one of the most dangerous space environment factors in LEO, which seriously affects the safe operation and service life of spacecraft in orbit. In order to meet the requirements for the high reliability and long lifetime of spacecraft, effective protection measures must be taken on their sensitive surfaces. Siloxane is a coating with an organic–inorganic hybrid structure. Compared with SiO2 and other inorganic atomic oxygen protective coatings, it has better flexibility and is better at anti-atomic oxygen performance. In this paper, the plasma polymerization deposition technique was used to prepare large-area siloxane coatings on different substrates with different thicknesses for improving atomic oxygen resistance by optimizing the process parameters. The thickness of the coating was measured by different methods, and the results showed that the thickness distribution was consistent. By observing the surface morphology of the coating, it was uniform and compact without obvious defects, so the uniformity of large-area coating was also ideal. The adhesion and heat/humidity resistance of siloxane coatings were examined by pull-off testing and damp-heat testing, respectively. The results showed that the siloxane coatings with a thickness of about 400 nm exhibited better physical properties. At the same time, the ground simulation testing of atomic oxygen confirmed that siloxane coatings with a thickness of 418 nm presented the best performance of atomic oxygen resistance. The atomic oxygen erosion yield of siloxane coatings with a thickness of 418 nm was as low as 5.39 × 10−27 cm3/atoms, which was three orders of magnitude lower than that of the uncoated Kapton substrate and presented a good anti-atomic oxygen performance. Meanwhile, it has also successfully passed the damp-heat test. The coating thickness is only several hundred nanometers and does not increase the weight of the spacecraft, which makes it a relatively ideal LEO atomic oxygen protection material. Furthermore, a possible mechanism was proposed to explicate the physicochemical process of atomic oxygen attacking the coating materials.

The microstructure evolution and impact toughness of the coarse grain heat-affected zone (CGHAZ) of TiNbV microalloyed steels were investigated by using a thermal simulation test. The samples were treated with various simulated welding thermal cycles. The phase constituents and grain sizes were analyzed by using electron backscatter diffraction analysis. The microstructure of the CGHAZ of the treated samples consisted of ferrite, acicular ferrite, pearlite, and bainite. The samples have a higher impact toughness under a lower welding heat input. This is because the microstructure of the CGHAZ is dominated by the higher volume fraction of the high-angle grain boundaries of acicular ferrites. The presence of bainite and coarsening grains are two key factors deteriorating the toughness of the CGHAZ of TiNbV microalloyed steels. The volume fraction of bainite sharply increased as the welding heat input increased, leading to a decrease in the impact toughness of the CGHAZ. For a higher welding heat input, both the severe coarsening of the grain size and a higher bainite content would result in poor impact toughness.

A soft body area sensor network presents a promising direction in wearable devices to integrate on-body sensors for physiological signal monitoring and flexible printed circuit boards (FPCBs) for signal conditioning/readout and wireless transmission. However, its realization currently relies on various sophisticated fabrication approaches such as lithography or direct printing on a carrier substrate before attaching to the body. Here, we report a universal fabrication scheme to enable printing and room-temperature sintering of the metal nanoparticle on paper/fabric for FPCBs and directly on the human skin for on-body sensors with a novel sintering aid layer. Consisting of polyvinyl alcohol (PVA) paste and nanoadditives in the water, the sintering aid layer reduces the sintering temperature. Together with the significantly decreased surface roughness, it allows for the integration of a submicron-thick conductive pattern with enhanced electromechanical performance. Various on-body sensors integrated with an FPCB to detect health conditions illustrate a system-level example.

The ultrasonic-assisted brazing of 30 vol.% Si3N4/6061Al composites in air using a filler metal comprising a Zn-Al alloy was investigated. Effects of the ultrasonic action duration and brazing temperature on the microstructure and mechanical properties of the brazed joints were focused on. The surface oxide layer between the composites and filler metals appeared to be broken and gradually removed by the ultrasonic action, and a composite bond with uniformly distribution of the reinforcements was formed eventually. As the ultrasonic action duration and brazing temperature increased, the proportion of Si3N4 particles and the atomic percentage of Al in the bond layer increased. Increasing the brazing temperature led to grain coarsening of the α-Al phase. The maximum shear bond strength of the joints was 183 MPa, and fracture occurred on the Al metal matrix composites side. The higher strength was attributed to the α-Al phase and Si3N4 particles being uniformly distributed in the bond layers.

Multilayer films with high-density layer interfaces have been studied widely because of the unique mechanical and functional properties. Magnetron sputtering is widely chosen to fabricate multilayer films because of the convenience in controlling the microstructure. Essentially, the properties of multilayer films are decided by the microstructure, which could be adjusted by manipulating the deposition parameters, such as deposition temperature, rate, bias, and target–substrate distance, during the sputter process. In this review, the influences of the deposition parameters on the microstructure evolution of the multilayer films have been summarized. Additionally, the impacts of individual layer thickness on the microstructure evolution as well as the irradiation behavior of various multilayer films have been discussed.

MoaMnTi10Ox (a= 0.2, 0.4, 0.6 and 0.8) catalysts have been prepared by sol-gel and applied in the NH3-SCR of NO reaction. These catalysts were characterized by XRD, H2-TPR, NH3-TPD, XPS and in situ DRIFTS. Among the MoaMnTi10Ox catalysts, Mo0.6MnTi10Ox exhibits the excellent NH3-SCR performance with a broaden activity temperature window even in presence of 5 vol.% H2O, together with an excellent resistance of H2O and SO2. Compared with MnTi10Ox, the Mo addition leads to the reduction of redox ability, improvement of the surface acid sites and inhibition of NO adsorption. A serial of characterizations confirms that the synergistic effect between redox property and surface acidity plays a key role in the much better NH3-SCR activity over Mo0.6MnTi10Ox. Furthermore, the in situ DRIFTS studies reveal the NH3-SCR reaction is following the E-R mechanism over Mo0.6MnTi10Ox at 210 °C. In addition, the effects of H2O on the NH3-SCR reaction are investigated by in situ DRIFTS.

Transparent electrodes for flexible and wearable devices require considerable stretchability and patterned conductive materials. Transparent and stretchable polydimethylsiloxane (PDMS) films with patterned cavities were prepared by laser processing and transfer printing. Transparent conductive ionic liquids (ILs) and aqueous solution (AS) were injected into the cavities, obtaining electrodes with transmittance in the visible range of 99.94% (relative to blank PDMS films) and 92.80% (relative to air). This transmittance was almost identical to that of a blank PDMS film. The maximum tensile strain applied to the electrodes was 117.23%, and the resistance of the electrodes with network patterns measured by the four-probe method was 3.20 kΩ. After 10,000 stretching/releasing cycles under strain of 0–50%, these electrodes still performed optimally. The ILs and AS showed various transmittance and electrical properties. The electrodes with ILs had higher transmittance, while those with AS showed increased conductivity. These electrodes with five patterns (serpentine, circle, straight line, fold line, and rhombus) were analyzed. The pattern containing curves with a large curvature would result in a severe local stress concentration in the stretching process. Patterns containing parallel curves could optimize electrical conductivity. And patterns containing complex curves had a certain effect on the transmittance. In addition, taking advantage of the fact that the elastomer and the liquid can deform at will, these electrodes were used to fabricate two pressure sensors and two strain sensors, which were employed to demonstrate their sensitivity stability during cycling.

A series of CeaMnOx hollow microsphere like arbutus with hierarchical structure are prepared by redox co-precipitation method and applied for catalytic toluene combustion. The Ce0.03MnOx shows a better catalytic performance for toluene combustion with high stability, water resistance, even under the condition of 5vol.% H2O. The results of XRF, XRD, Raman, N2 adsorption-desorption, SEM, TEM prove that the doping of Ce can affect the structure of CeaMnOx such as much smaller particle size and higher specific surface area. The characterizations of H2-TPR, O2-TPD, XPS certify the strong interaction between Ce and Mn oxides that leads to more surface adsorbed oxygen and Mn4+ species due to oxidation reduction cycle of Mn3+ + Ce4+ ↔ Mn4+ + Ce3+ after Ce addition. Meanwhile, the Toluene-TPD in different conditions confirms the introduction of water promoted the catalytic oxidation of toluene. In situ DRIFTS is used to investigate the reaction process of toluene oxidation. And the results reveal that the Ce0.03MnOx catalyst has much stronger ability to adsorb and activate toluene compared with MnOx catalyst, especially under with H2O. That may be the main reason that the Ce0.03MnOx catalyst exhibits the special catalytic activity for toluene combustion.

Carbon nanotube (CNT)-reinforced magnesium (Mg) matrix composites were fabricated through a three-step preparation process which consists of mixed ball-milling, melt processing, and hot extrusion process. The results show that mechanical ball-milling well-dispersed CNTs on zinc flakes and uniform distribution of CNTs were obtained in the composites after melt processing and hot extrusion process. Aluminum (Al) with a mass fraction of 0.3% was added into the composite melt before casting so as to induce interfacial reaction on the surface of CNTs. Consequently, in comparison with Mg-6Zn/CNT composites, the yield strength and ultimate strength of Mg-6Zn-0.3Al/CNT composites increased by 21.1% and 9.3%, respectively. Unlike CNTs in the Mg-6Zn/CNT composites, a great amount of nanosized aluminum phases which were validated to be aluminum oxide (Al2O3) were found on the surface of CNTs in the Mg-6Zn-0.3Al/CNT composites. The interfacial reaction transformed the physical combination of CNT-Mg interface into reaction bonding which increased the efficiency of load transfer contributed by CNTs.

A series of Ce0.1TiOx, Cu0.1Ox and CumCe0.1-mTiOx (m = 0.01, 0.02, 0.03) catalysts are prepared via a sol-gel method for the selective catalytic reduction (SCR) of NO with NH3. The samples are mainly characterized by X-ray diffraction (XRD), Raman, H2-TPR, NH3-TPD, separated NO/NH3 oxidation, X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to investigate the properties of the catalysts. Among the CumCe0.1-mTiOx (m = 0.01, 0.02, 0.03) catalysts, Cu0.01Ce0.09TiOx displays much better catalytic activity in the range of 170 °C–425 °C (> 90% NO conversion), N2 selectivity and resistance of SO2 and H2O even at high gas hourly space velocity. The XPS results verify that the introduction of Cu leads to a copper species enrichment environment and the formation of more surface Ce3+ and absorbed oxygen (Oα), which are in favor of the oxidation of NO to NO2, enhancing the activity at low temperature. Furthermore, in situ DRIFTS results confirm that the Langmuir-Hinshelwood (L-H) mechanism is predominant in the NH3-SCR process for the Cu0.01Ce0.09TiOx catalyst at 150 °C.

Citric acid method was employed to prepare a series of Nb-promoted Fex-Nb0.5-x-Ce0.5 (x = 0.45, 0.4, 0.35) oxides for selective catalytic reduction with NH3 (NH3-SCR) of NO process. The structure, redox ability and reactivity of NH3 and absorbed NO species on the catalysts were explored by using various characterization techniques such as X-ray diffraction (XRD), temperature program reduction with H2 (H2-TPR), temperature program desorption of NH3 (NH3-TPD), temperature program desorption of NO (NO-TPD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS). It was found that the Nb promoted Fex-Nb0.5-x-Ce0.5 (x = 0.45, 0.4, 0.35) oxides catalysts showed outstanding NH3-SCR of NO activity, excellent N2 selectivity and remarkable SO2/H2O resistance, meanwhile, Fe0.4-Nb0.1-Ce0.5 exhibited above 90% NO conversion in the range of 180–400 °C, together with near 100% N2 selectivity. The characterization results point out that the excellent catalytic performance of Fe0.4-Nb0.1-Ce0.5 can be ascribed to the strong interaction among Nb, Fe and Ce oxides. The strong interaction not only increases the BET surface area and redox ability of the catalyst, but also significantly improves the acid amount leading to the enhancement of the adsorption and activation of NH3, which is advantage of the reactivity of adsorbed nitrate together with the adsorbed NH3 species.

A convenient sol-gel method was used to prepare a series of MnaCe0.3TiOx (a = 0.1, 0.2, 0.3) catalysts and applied in selective catalytic reduction with NH3 (NH3-SCR) for NO removal. XRD, BET, Raman, H2-TPR, NH3-TPD, SO2-TPD, XPS and in situ DRIFTS were applied to analyze the texture structure, redox property, acidity and surface properties. The Mn0.1Ce0.3TiOx catalyst exhibited a dramatical performance that 100% NO conversion and above 90% N2 selectivity were obtained between 175 and 400 °C, even under high gas hourly space velocity of 80,000 h−1 and existence of SO2 and H2O. The results can be attributed to that Mn0.1Ce0.3TiOx catalyst possessed the most chemisorbed oxygen and suitable redox property derived from Ce3+ + Mn4+ ↔ Ce4+ + Mn3+ reaction. In situ DRIFTS revealed that the NH3-SCR reaction upon Mn0.1Ce0.3TiOx catalyst took place by L-H and E-R mechanisms below 175 °C while only E-R mechanism above 175 °C.

The Cux-Nb1.1-x (x = 0.45, 0.35, 0.25, 0.15) bimetal oxides catalysts were synthesized through citric acid method and used in the selective catalytic reduction (SCR) of NO with NH3. The relationship among the catalytic performances, the acid/redox properties and the structures of the binary oxides systems was explored through different characterization techniques including XRD, H2-TPR, BET, NO-TPD, NH3-TPD, XPS and in situ DRIFTS. The characterization results point out that the ratio of Cu to Nb has great influence on the activity of NH3-SCR reaction. Different catalytic activities of Cux-Nb1.1-x (x = 0.45, 0.35, 0.25, 0.15) mixed oxides could be attributed mainly to surface area, acid amount, the adsorption and activation of NH3 and redox ability of the corresponding catalyst. Among these Cux-Nb1.1-x (x = 0.45, 0.35, 0.25, 0.15) oxides catalysts, the Cu0.25-Nb0.85 catalyst exhibited the complete NO conversion in a reaction temperature range of 180-330 °C, together with near 100% N2 selectivity and remarkable SO2/H2O resistance. Moreover, the Cu0.25-Nb0.85 catalyst still exhibited wide activity temperature window of 185-380 °C at above 90% NO conversion even in the presence of 5% H2O under high GHSV of 70,000 h-1. Thus, it can be summarized from the above results that Cu0.25-Nb0.85 can be considered as excellent catalyst for NH3-SCR of NO.

Ductile aluminum matrix composites reinforced by Al18B4O33 whisker (ABO) with band-like distribution (Band-like Aluminum Matrix Composites, BAMCs) were fabricated by powder metallurgy and extrusion followed by annealing. The cracks tend to nucleate in the ABO-rich bands, but the band-like structure induces compressive residual stress then suppresses the crack propagation and improves the strain transferring ability in the BAMCs. The denser and smaller cracks formed in the BAMCs with higher ABO volume fraction during tensile test. These cracks play an important role in the strain non-localization process, but have negligible contribution to the tensile strain.

SiC ceramics were successfully soldered with the assistance of ultrasound. Two kinds of filler metals, namely non-eutectic Zn–5Al–3Cu and eutectic Zn–5Al alloys, were used. The effects of ultrasonic action on the microstructure and mechanical properties of the soldered joints were investigated. The results showed that ultrasound could promote the wetting and bonding between the SiC ceramic and filler metals within tens of seconds. For the Zn–5Al–3Cu solder, a fully grain-refined structure in the bond layer was obtained as the ultrasonic action time increased. This may lead to a substantial enhancement in the strength of the soldered joints. For the Zn–5Al solder, the shear strength of the soldered joints was only ∼102 MPa when the ultrasonic action time was shorter, and fractures occurred in the brittle lamellar eutectic phases in the center of the bond layer. With increasing ultrasonic action time, the lamellar eutectic phase in the bond layer of SiC joints could be completely transformed to a fine non-lamellar eutectic structure. Meanwhile, the grains in the bond layer were obviously refined. Those results led to the remarkable enhancement of the shear strength of the joints (∼138 MPa) using the Zn–5Al solder, which had approached that enhancement using the Zn–5Al–3Cu solder. The enhanced mechanical properties of the joints were attributed to the significant refinement of the grains and the change in the eutectic structure in the bond layer. Prolonged enhanced heterogeneous nucleation triggered by ultrasonic cavitation is the predominant refinement mechanism of the bond metals of the SiC joints.

High-performance aluminium matrix composite joints were fabricated using a new joining technology assisted by ultrasonic vibration. The performance of the joints was close to that of the parent materials. The microstructure and the mechanical performance were found to be systematically dependent on the volume fraction and the distribution of reinforcement particles in the bond region. The authors believe that this study can be generalised to the bonding of other ceramic-reinforced metal matrix composites.

A series of Cux-Ce0.5-x-Zr0.5 oxides catalysts with different Cu/Ce ratio were synthesized by citric acid method. The catalysts were characterized by XRD, BET surface area, H2-TPR, NH3-TPD, NO-TPD, XPS and in-situ DRIFTS. The synergistic effect between copper and cerium on the catalytic performance of Cux-Ce0.5-x-Zr0.5 for selective catalytic reduction of NO with ammonia was investigated. It was found that the Cu0.2-Ce0.3-Zr0.5 catalyst show the excellent SCR activity, N2 selectivity and H2O/SO2 durability in a low temperature range of 150–270 °C even at high gas hourly space velocity of 84,000 h−1. The strong interaction leads to the improvement of the acidity and the increase in the amount of active oxygen species (oxygen vacancy), which are responsible for the higher activity at low temperatures. The SCR reaction process over Cu0.2-Ce0.3-Zr0.5 was also examined using in-situ DRIFTS. The DRIFTS results indicate that abundant ionic NH4+ (Bronsted acid sites), coordinated NH3 on the Lewis acid sites, as well as highly active monodentate nitrate and bridging nitrate species were the key intermediates in the SCR reaction.

High strength aluminum alloys are extremely sensitive to the thermal cycle of welding. An ultrasonic-promoted rapid TLP bonding with an interlayer of pure Zn was developed to join fine-grained 7034 aluminum alloys at the temperature of lower 400°C. The oxide film could be successfully removed with the ultrasonic vibration, and the Al-Zn eutectic liquid phase generated once Al and Zn contacted with each other. Longer ultrasonic time can promote the diffusion of Zn into the base metal, which would shorten the holding time to complete isothermal solidification. The joints with the full solid solution of α-Al can be realized with the ultrasonic action time of 60s and holding time of only 3min at 400°C, and the shear strength of joints could reach 223MPa. The joint formation mechanism and effects of ultrasounds were discussed in details.

Soldering aluminum alloys at low temperature have great potential to avoid softening of base metals. Pure Al was soldered with pure tin assisted by ultrasound. The influence of primary α(Al) on the microstructure of Al/Sn interface and its bonding strength was studied. It is found that the primary α(Al) in liquid tin tends to be octahedron enclosed by Al {111} facet with the lowest surface free energy and growth rate. The ultrasonic action could increase the nucleation rate and refine the particles of primary α(Al). For the longer ultrasonic and holding time, a large amount of the octahedral primary α(Al) particles crystallize at the Al/Sn interface. The bonding interface exhibits the profile of rough dentation, resulting in an increment of bonding interface area and the effect of mechanical occlusion. The bonding strength at interface could reach 63 MPa with ultrasonic time of 40 s and holding time of 10 min.

With the aim of overcoming the limitations of traditional soldering ceramic methods for power device packaging, a simple but ultrafast bonding technology is reported. The effect and mechanism of ultrasonic action on the interfacial bonding and microstructure is investigated and thoroughly discussed. An ultrafast interfacial bond between SiC ceramics and SnAgTi active solder has been successfully achieved through a reaction at the interface at a low temperature of 250 °C in the extremely short time. High-resolution transmission electron microscopy (HRTEM) revealed that a silica layer on the surface of SiC reacted with Ti from the SnAgTi active solder to form a nanometer-thickness amorphous titania layer at the interface under the ultrasonic action, which creates an exceptional interfacial structure and facilitates bonding between the two dissimilar crystals. A discontinuous titania layer at the interface was identified within 0.1 s. With further increasing ultrasonic action time to 1 s, a continuous titania layer with a thickness of 7.6 ± 0.5 nm formed at the interface. A new interfacial reaction mechanism was revealed and it was found that ultrasound accelerated the reaction of liquid active solder/ceramic. Our finding demonstrated that ultrasound could be an effective approach for joining ceramics which is difficult to wet by a liquid metal at low temperature. The combined impact of ultrasonic cavitation and streaming dominated the mechanism and kinetics of the rapid interfacial reaction.

Doped with various mole fractions of ZnO (2%, 4%, 7%, 8%) and 0.03 wt.% Fe 2 O 3 in LiNbO 3 , a series of Zn:Fe:LiNbO 3 crystals were grown by Czochralski method and then the crystals were polarized and oxidized. Holograms were thermally fixed in Zn (2 mol%):Fe (0.03 wt.%):LiNbO 3 crystal by heating the crystal to roughly 120 °C for 40 min. After the developing process, 200-h lossless readout data were obtained in the thermal fixing and developing experiments. The 200-h data are predicted to be read out around 72 million times, which is superior to the lifetime of hard disks. Furthermore, decays of thermally fixed holograms in Zn:Fe:LiNbO 3 crystals with various mole fractions of ZnO (2%, 4%, 7%, 8%) were measured at 20 °C. The results show that the ionic activation energies are 1.115 eV, 1.128 eV, 1.275 eV, 1.278 eV, respectively. Extrapolated hologram lifetimes as long as 20 times up to 30 times longer than that of Fe:LiNbO 3 crystal (5.2 years) at 20 °C were determined. Finally, the threshold value of Zn 2+ concentration was identified by the location of OH − absorption peak of infrared spectra and the ionic activation energy relative to thermal fixing of grating suggests significant threshold effect along with the variation of Zn 2+ concentrations.

Under the background of "Internet + Education", the educational APP is explored and designed. This paper uses the literature method, the questionnaire survey method and combines with the actual development process to design the Physics Experiment Station APP for University of Science and Technology of Liaoning, and describes the core components, techniques and designs principles of each function module, in order to promote teaching of college physics experiment and make some contributions to the educational APP development.

A serial of novel NimCo0.3-mTi0.7Ox (m = 0.05-0.25) mixed-oxide catalysts was synthesized by sol-gel method, and applied for selective catalytic reduction (SCR) of NOx by NH3. Influences of the Ni/Co ratio on the physico-chemical properties and SCR performance were characterized by various analytical techniques, including BET surface area, XRD, XPS, NH3-TPD, H2-TPR and in situ DRIFTS. The Ni0.1Co0.2Ti0.7Ox catalyst shows optimum NH3-SCR activity and excellent N2 selectivity with a broader activity temperature window (210–450 °C), which is associated with the much higher BET surface area, more surface acid amounts and the suitable redox ability derived from the strong interaction between Co and Ni (Co3+ + Ni2+ ↔ Ni3+ + Co2+). In situ DRIFTS results reveal that the formed monodentate nitrate and NH2 species, as main active intermediates, are favor of the NH3-SCR reaction. The existence of H2O mainly restrains Langmuir-Hinshelwood reaction pathway which may be the main cause for the catalyst deactivation.

A series of ZnWO 4 crystals with different purities of WO 3 and ZnO were grown by conventional Czochralski method and compared with Fe:ZnWO 4 , Nb:ZnWO 4 , Ag:ZnWO 4 and Ce:ZnWO 4 crystals grown by the same technology. Scintillation experiments revealed that the light yield of undoped ZnWO 4 crystals varied with the purities of raw materials WO 3 and ZnO. Raising the concentration of iron ions in ZnWO 4 crystals resulted in reduction of the light yield from the lighter appearance. On the contrary, the light yield was enhanced by doping Ag 2 O, Nb 2 O 5 and CeO 2 , equivalent to that observed in ZnWO 4 crystals after oxygen-rich annealing at high temperature. The mechanisms of coloration and decolorization in doped ZnWO 4 crystals were analyzed. And the relationship between enhanced scintillation properties and the color center complex of iron impurity and oxygen vacancy in the crystals was discussed.

The growth of intermetallic compounds at the interface between solid Al and Fe and the effects of intermetallic compound layers on the interfacial bonding of clad materials were investigated. The results showed that the interface between the solid Fe and Al formed by heat-treatment consisted of Fe 2 Al 5 and FeAl 3 intermetallic compound layers, which deteriorated the interfacial bonding strength. Fractures occurred in the intermetallic compound layer during the shear testing. The location of the fracture depended on the defects of microcracks or voids in the intermetallic compound layers. The microcracks in the intermetallic compound layer were caused by the mismatch of thermal expansion coefficients of materials during cooling, and the voids were consistent with the Kirkendall effect. The work will lay an important foundation for welding and joining of aluminum and steel, especially for fabrication of Al-Fe clad materials.