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In Inconel 783 alloy, there are mainly two kinds of strengthening phases of β and γ’. In addition, it is found that there are other precipitated phases in the alloy’s β phase. By means of multiple testing methods, the types and functions of the precipitated phase in the β phase were determined. The results showed that the precipitated phases from β phase were nanoscale Nb and Ti carbides and a large number of white needle-like Laves phases. The former, due to its small size, which can improve the grain boundary slip resistance of the alloy, thus improves the shaping of the material. While the latter, due to its sharp shape and due to its large amount, destroys the original structure of the β phase and greatly reduces the room temperature plasticity of the alloy.

The thick titanium nitrides coating was fabricated on LZ91 alloy by surface mechanical nano-alloying (SMNAT) combined with gas nitriding. Experimental results showed that a nanostructured titanium ...

In this paper, the removal of the sulfide layer formed on an FV(520)B stainless steel in the simulated environment of air compressor blade service conditions in a reaction kettle by arc plasma was investigated to explore the mechanism and technology of the sulfide layer removed by arc plasma from a blade surface. The sulfide lattice energy is studied by using the Born Haber cycle. Besides, the energy balance of the removal process is calculated. The treated surface morphology of samples was analyzed by scanning electron microscopy and energy dispersive spectrometer. The results indicate that the energy of the arc spot is enough to evaporate the sulfide film. Due to the different electronic work functions, an arc spot is first formed on the sulfide film, and then the voltage signal is segmented during the removal process. The voltage signal in the removal process can remove sulfide without harming the metal matrix. Besides, the increase in current can improve the removal efficiency and the surface roughness of the sample. It can be revealed, by analyzing the surface composition of samples with different currents, that the sulfur content is very low, indicating that it is feasible to remove the sulfide layer by arc spot plasma.

High-performance fabrics with excellent electrical conductivity are increasingly attractive in modern industries. In this study, we report an electrically conductive silver/polyimide fabric (Ag/PIF) composite fabricated by combining an O 2 plasma pretreatment and a spray-assisted electroless plating (SAELP) technique. O 2 plasma treatment is firstly employed to roughen the surface of PIF and introduce functional aldehyde or ketone groups, which can act as a reducing agent and facilitate an even nucleation initiation of silver nanoparticles (Ag NPs) on the surface of the PIF. A silver ion solution and a reducing agent are then mixed evenly and sprayed to the PIF immediately to obtain Ag/PIF composites. The effects of O 2 plasma treatment and SAELP duration on the Ag/PIF composites are investigated and discussed. The results demonstrate that the silver layer is coated on the PIF uniformly and densely with a surface resistance of 0.1 Ω/sq. The first decomposition temperature of the Ag/PIF composites is up to 600 °C, indicating excellent thermal stability. The enhanced adhesion between Ag NPs and PIF endows the composites excellent fastness and superior flexibility. This work gives a new strategy for fabricating flexible, electrically conductive functional metal coated fabrics with high-performance properties in an efficient, facile and scalable way.

The effects of Nb addition on the microstructure and corrosion resistance of the as-rolled Ti-stabilized Fe-17Cr ferritic stainless steels were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction, pitting tests, and electrochemical measurements. TiN precipitate tends to form in the microstructure of Ti-stabilized Fe-17Cr ferritic stainless steel. After 0.1 wt. % Nb addition, (Ti, Nb) (C, N) composite precipitates with MgO and Al2O3 core form in the microstructure. After adding 0.1 wt. % Nb, the corrosion rate of the Ti-stabilized Fe-17Cr ferritic stainless steel in FeCl3 solution is decreased significantly. The corrosion current densities decrease in HNO3, NaOH, and NaCl solutions, and the pitting corrosion potentials can be improved in NaCl solution for the Fe-17Cr ferritic stainless steel with 0.1 wt. % Nb addition.

The effect of Sc on the microstructure and mechanical properties of Al–Si–Mg–Cu–Ti alloy was investigated. Results obtained in this research indicate that, with increasing Sc content, the microstru...

This paper presents an experimental investigation on the knittability of various polyimide (PI) filaments, namely PI-H (high strength and modulus), PI-M (moderate strength and modulus) and PI-L (low strength and modulus) filaments. The tensile strength of the PI-H, PI-M and PI-L filaments is 3.41, 1.65 and 0.88 GPa, and the Young’s modulus is 92.94, 40.71 and 9.43 GPa, respectively. The chemical compositions and structures of various PI filaments were characterized to explain the mechanical performance differences. The results show that the imidization degree, structural crystallinity and orientation have significant effects on the mechanical behaviors of PI monofilaments. The filament forces during the knitting process are simplified into straight tensile, loop tensile and abrasion actions, which have been tested and analyzed on PI monofilaments. A home-made simulative knittability analyzer was designed to test the knittability of the PI filaments. A hand flat knitting machine was used to verify the validity of the simulating methods and the constructed knittability analyzer. The PI-H, PI-M and PI-L filaments have poor, moderate and excellent knittability, respectively. The results also demonstrate that the simulating methods and the constructed simulative knittability analyzer are reasonable and efficient to evaluate the knittability of PI filaments.

A WC-reinforced composite coating was fabricated on the surface of 45 steel samples by plasma, cladding process with WC powder added to the molten pool synchronously or in the tail of the molten pool. The microstructure, phase composition, and element distribution in the coating were analyzed. The results show that the undissolved WC particles and crystallized carbide (WC, W2C) were distributed uniformly in the sub-eutectic matrix in both cases. Fewer of the WC particles are dissolved in the matrix when they are injected into the tail of the molten pool. There are fewer needle-like tungsten carbide formations seen in the composite coating fabricated by back-feeding process than in that formed by synchronous feeding. The former results in a finer microstructure and a higher concentration gradient of elements near the interface between the WC particles and the coating matrix.

Primary particles formed in as-cast Al-5Mg-0.6Sc alloy and their role in microstructure and mechanical properties of the alloy were investigated using optical microscopy (OM), scanning electron microscopy (SEM), electron back-scatter diffraction (EBSD) and tensile testing. It was found that primary particles due to a close orientation to matrix could serve as the potent heterogeneous nucleation sites for α-Al during solidification and thus impose a remarkable grain refinement effect. Eutectic structure consisted of layer by layer of ‘Al 3 Sc + α-Al + Al 3 Sc + ⋯’ and cellular-dendritic substructure were simultaneously observed at the particles inside, indicating that these particles could be identified as the eutectics rather than individual Al 3 Sc phase. A calculating method, based on EBSD results, was introduced for the spatial distribution of these particles in matrix. The results showed that these eutectic particles randomly distributed in matrix. In addition, the formation of primary eutectic particles significant improved the strength of the Al-Mg alloy in as-cast condition, which is ascribed to the structural evolution from coarse dendrites to prefect fine equiaxed grains. On the other hand, these large-sized particles due to the tendency to act as the microcrack sources could cause a harmful effect in the ductility of Al-Mg-Sc alloy.

An addition of a high level of 0.6 wt% Sc imposed a remarkable grain refining effect on Al-5Mg alloy for as-cast condition, changing typical dendritic microstructure into fine equiaxed grains. Such effect was found to be related to the extensively formed Sc-rich particles. Electron back-scatter diffraction (EBSD), Atomic force microscopy (AFM) and SEM-elemental mapping were employed to investigate the inner structure of these particles and their role in grain refining. They could be identified as some eutectic structure consist of multilayer of ‘Al 3 Sc + α-Al+Al 3 Sc····’, which shows good consistency in orientation both in the particle and matrix.

The effect of Sc addition on microstructure and mechanical properties of as-cast Al–Mg alloys was investigated based on optical microscopy (OM), scanning electron microscopy (SEM), electron back-scatter diffraction (EBSD) and properties testing. The results showed that a remarkable grain refining effect was observed for Sc content greater than 0.4 wt.%, changing typical dendritic microstructure into fine equiaxed grains. Such effect was found to be related to the formed primary particles, which hindered the undesirable diffusion and subsequent crystal growth and acted as potent heterogeneous nucleation sites for α-Al matrix during solidification. In addition, these particles could cause a significant refinement strengthening effect. Atomic force microscopy (AFM) and SEM-elemental mapping were employed to investigate the internal structure and elemental distribution of these particles. They could be identified as the eutectics consisted of Al3Sc and α-Al phases rather than individual Al3Sc phase, which exhibited an ‘Al3Sc + α-Al + Al3Sc⋯’ multilayer structure. Keywords: Al–Mg–Sc alloys, Grain refinement, Eutectics, Multilayer structure

In this study, SiC particles were first coated with Cr to form a layer that can protect the SiC particles from dissolution in the molten pool. Then, the Cr-SiC powder was injected into the tail of molten pool during plasma-transferred arc welding process (PTAW), where the temperature was relatively low, to prepare Cr-SiC particles reinforced Fe-based alloy coating. The microstructure and phase composition of the powder and surface coatings were analyzed, and the element distribution and hardness at the interfacial region were also evaluated. The protective layer consists of Cr3Si, Cr7C3, and Cr23C6, which play an important role in the microstructure and mechanical properties. The protective layer is dissolved in the molten pool forming a flocculent region and a transition region between the SiC particles and the matrix. The tribological performance of the coating was also assessed using a ring-block sliding wear tester with GGr15 grinding ring under 490 and 980 N load. Cr-SiC particles-reinforced coating has a lower wear rate than the unreinforced coating.

Polyimide (PI) is one of the lightweight and high-performance materials, having great potential to be used as reinforcements for advanced composites. Quantitative evaluation of fiber/matrix interface is critical in designing fiber reinforced polymer composites. However, there is a lack of effect characterization methods to measure the interfacial shear strength (IFSS) of polyimide fiber (PIF) due to its high failure strain. In this study, a modified single fiber fragmentation test (SFFT) was proposed to solve this problem. By employing Polyurethane (PU) resin as an additive in commercial epoxy resin, a transparent PU modified epoxy (PU-epoxy) resin is obtained. The PU-epoxy has a failure strain of 137.93%, which is much larger than 14.83% of the PIF, meeting the pre-requirement of SFFT. Oxygen plasma treatment is applied to modify surface properties of the PIF to improve its interfacial adhesion with epoxy. Statistical results show that a plasma-treated PIF for 4 mins achieves a 125.41% increase in IFSS compared with the pristine PIF. Meanwhile, a finite element model (FEM) is created to simulate and visualize stress distribution in fiber, interface, and matrix during the SFFT.

In the present study, the effects of Mg, Cu, Sc and Zr combined additions on the microstructure and mechanical properties of hypoeutectic Al–Si cast alloy were systematically investigated. Characterization techniques such as optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), electron back-scatter diffraction (EBSD), atomic force microscopy (AFM), transmission electron microscope (TEM), Brinell hardness tester and universal testing machine were employed to analyze the microstructure and mechanical properties. The results showed that Sc served as modifier on the microstructure of Al–3Si–0.45Mg–0.45Cu–0.2Zr alloys, including modification of eutectic Si and grains. Extraordinarily, grain refinement was found to be related to the primary particles, which exhibited a close orientation to matrix. After T6 heat treatment, the grain structures were composed of nano-scaled secondary Al3(Sc, Zr) precipitates and spherical eutectic Si. Combined with T6 heat treatment, the highest hardness, yield strength, ultimate tensile strength and elongation were achieved in 0.56 wt.% Sc-modified alloy. Interestingly, the strength and ductility had a similar tendency. This paper demonstrated that combined additions of Mg, Cu, Sc and Zr could significantly improve the microstructure and performance of the hypoeutectic Al–Si cast alloy.

WC-Fe composite coatings were prepared on IC45/080A47 steel substrates by argon arc cladding technique. Minute amounts of La were added into the coating, and the microstructure was investigated to find the relation to rare earth. Results show that RE does not change the categories of phases, and the main components remain α-Fe, Fe3W3C, WC and W2C. However, the distribution of carbide particles is optimised. It reduces the agglomeration and bridging in the cladding layer's structure, makes the particles distribute homogeneously and restrains the dissolution of WC and the formation of fishbone shaped dendritic carbides. It promotes the formation of granular carbide and refines grains. It also reserves the WC particles in the composite coating and improves the average hardness and wear resistance.

The assimilation properties of iron ores are important during sintering. The amount of formed calcium ferrite was firstly used to evaluate the assimilation. Then, temperature and time of assimilation were proposed rather than the former one, which simplify the process and improve the operahility of experiments. However, the factors affecting the temperature were always neglected and using several indexes to evaluate the assimilation was inconvenient. In this paper, the assimilation reaction characteristic number taking the actual sintering temperature as the reference temperature was put forward to evaluate the assimilation of iron ores. This assimilation reaction characteristic number was a dimensionless number including kinds of important information during the assimilation reaction process. Results showed that the assimilation characteristic number can reflect the overall process of assimilation reaction between ores and CaO, which could help further analyze the assimilation difference of ores.

The impact-corrosion-abrasion resistance of the low carbon high alloy steel, which can be used for mill lining under impact-corrosion-abrasion condition, are tested in laboratory by means of a new kind of experimental facility. The industrial trial run in the same condition has also been completed. The results show that the new alloy containing 0.2 wt.% carbon, 9 wt.% chromium, and 2 wt.% nickel is consisted of lath martensite entirely, and is more than two times superior to Mn13 cast steel in impact-corrosion-abrasion resistance. Spelling is the leading wear mechanism in impact-corrosion-abrasion condition for this alloy, which is lighter than that of high manganese steels because of its better hardness-toughness match.

The impact corrosion-abrasion properties and mechanism of high manganese steel were investigated under different impact energies. The result shows that the wearability of the steel decreases with the increase of the impact energy. The dominant failure mechanism at a lower impact energy is the rupture of extrusion edge along root and a slight shallow-layer spalling. It transforms to shallow-layer fatigue flaking along with serious corrosion-abrasion when the impact energy is increased, and finally changes to bulk flaking of hardened layer caused by deep work-hardening and heavy corrosion-abrasion.

The abrasion behavior of high manganese steel is investigated under three levels of impact energy in acid-ironstone slurry. The wear test was carried out by an MLDF-10 tester with impact energy of 0.7 J, 1.2 J, and 1.7 J. The impact abrasion property of high manganese steel in corrosive condition was compared according to the wear mass loss curves. The wear mechanism was analysed by the SEM analysis of the worn surface and the optical metallographic analysis of the vertical section to the wear surface. The results show that the impact energy has a great effect on the impact corrosion and abrasion properties of it. Its abrasion mechanism in corrosive condition is mainly microplough and breakage of plastic deformed ridges and wedges under the impact energy of 0.7 J. It is mainly the spelling of plastic deformed ridges and wedges under 1.2 J and the spalling of the work-hardening layer under 1.7 J after a long time testing.