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In order to solve the problems of high porosity and poor wear resistance of molybdenum (Mo) coating deposited by atmospheric plasma spraying (APS), the in situ laser-assisted plasma spraying (LAPS) technology was adopted to prepare Mo coating, and the effect of laser power on the microstructure, phase composition, microhardness and frictional wear performance was investigated. Results indicated that the porosity of LAPS coating was lower than that of plasma-sprayed coating, while the microhardness of LAPS coating was better than that of plasma-sprayed coating. As for LAPS coating with laser power of 500 W, the porosity is the lowest and the microhardness is the highest. Friction and wear test results showed that the friction coefficient of the LAPS Mo coating was lower than that of the plasma-sprayed Mo coating. The LAPS Mo coating exhibited better wear resistance than the plasma-sprayed Mo coating, which was mainly attributed to the self-lubricating effect of MoO2 generated from the oxidation of a small amount of Mo under the action of high energy density laser. The wear failure mechanisms of the plasma-sprayed and LAPS Mo coatings were adhesive wear, abrasive wear and oxidative wear of different degrees. [ABSTRACT FROM AUTHOR]

The extremely harsh environment of the high temperature plasma imposes strict requirements on the construction materials of the first wall in a fusion reactor. In this work, a refractory alloy system, WTaVTiZrx, with low activation and high entropy, was theoretically designed based on semi-empirical formula and produced using a laser cladding method. The effects of Zr proportions on the metallographic microstructure, phase composition, and alloy chemistry of a high-entropy alloy cladding layer were investigated using a metallographic microscope, XRD (X-ray diffraction), SEM (scanning electron microscope), and EDS (energy dispersive spectrometer), respectively. The high-entropy alloys have a single-phase BCC structure, and the cladding layers exhibit a typical dendritic microstructure feature. The evolution of microstructure and mechanical properties of the high-entropy alloys, with respect to annealing temperature, was studied to reveal the performance stability of the alloy at a high temperature. The microstructure of the annealed samples at 900 °C for 5–10 h did not show significant changes compared to the as-cast samples, and the microhardness increased to 988.52 HV, which was higher than that of the as-cast samples (725.08 HV). When annealed at 1100 °C for 5 h, the microstructure remained unchanged, and the microhardness increased. However, after annealing for 10 h, black substances appeared in the microstructure, and the microhardness decreased, but it was still higher than the matrix. When annealed at 1200 °C for 5–10 h, the microhardness did not increase significantly compared to the as-cast samples, and after annealing for 10 h, the microhardness was even lower than that of the as-cast samples. The phase of the high entropy alloy did not change significantly after high-temperature annealing, indicating good phase stability at high temperatures. After annealing for 10 h, the microhardness was lower than that of the as-cast samples. The phase of the high entropy alloy remained unchanged after high-temperature annealing, demonstrating good phase stability at high temperatures. [ABSTRACT FROM AUTHOR]

Laser cladding is a promising surface modification technology to fabricate high-performance parts. However, defects such as porosity, cracks and residual tensile stress are easily produced in laser cladding, leading to significant property reduction and poor reliability. In this study, laser cladding with multidimensional high-frequency vibration was investigated. The effects of multidimensional high-frequency vibration on the improvement of microstructure and mechanical properties were analyzed and discussed based on the vibration-assisted laser cladding experiments. In addition, a numerical model was conducted to help understand the significance of the vibration on flow field and temperature field. Results show that 3D vibration led to the primary dendrite spacing reduction from 11.1 to 6.8 μm, microhardness increase from 199 to 221 HV0.2, and a nearly 110% improvement in the elongations. The findings of this study confirmed the significant benefits of multidimensional high-frequency vibration applied in laser cladding and provided a basis to uncover the underlying mechanisms of multidimensional vibration on the rapid melting and solidification. [ABSTRACT FROM AUTHOR]

Porous TiO2 ceramic coatings with high contents of Si and P were fabricated on a Ti6Al4V alloy using hybrid processing of laser surface melting (LSM) and microarc oxidation (MAO). The effect of LSM pretreatment on the growth behavior and mechanical properties of the MAO coating was studied. The results showed that the MAO coating on LSM pretreatment Ti6Al4V (LSM-MAO) had quite different surface morphologies, thickness, and compositions compared to the MAO coating on as-received titanium alloy. Grain refinement and dislocation in the LSM-treated Ti6Al4V alloy provided extra energy and more numbers of discharge channels during the MAO process. LSM–MAO coating exhibited a more uniform pore distribution, relatively small pores, and larger thickness compared to the MAO coating. The LSM-MAO coating had higher hardness and better wear resistance than the MAO coating. LSM is deduced to be an appropriate and efficient pretreatment method for achieving a high-quality MAO coating on titanium alloy. [ABSTRACT FROM AUTHOR]

As a widely used approach for surface modification, laser cladding plays a significant role in surface hardening and repairing of metallic parts. However, the defects existing in laser cladding parts, such as cracks, tensile residual stress, and pores, significantly affect the performance and the application of the cladding parts. In this study, an SS316L layer was fabricated on a 45 steel substrate using a laser cladding process assisted by three-dimensional vibration. The microstructures and the properties of the coating and the bonding interface with various vibration parameters were analyzed and compared. The microstructures of the cladding layer and the matrix were analyzed by an optical microscope and a scanning electron microscope. The results show that the three-dimensional vibration is able to refine the columnar dendrites in the cladding layer. The oscillation accelerates both the liquid flow and the thermal transfer of the molten pool, which not only reduces the temperature gradient but also increases the solidification growth rate. Meanwhile, the porosity and the maximum pore size in the cladding layer were significantly reduced by the vibration. The average microhardness of the cladding layer significantly increased assisted by the three-dimensional vibration. Experimental results demonstrate that the effects of the three-dimensional vibration are more significant than the single vertical vibration. The proposed approach provides a potential way to improve laser additive manufacturing and remanufacturing. [ABSTRACT FROM AUTHOR]

The distribution of WC particles in laser cladded composite coatings can significantly affect the wear resistance of the coatings under aggressive environments. In this study, pre-alloyed WC-NiCrMo powder is deposited on SS316L via laser cladding with circular spot and wide-band spot, respectively. The microstructure and WC distribution of the coatings are investigated with optical microscope (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). The wear behavior of the coatings is investigated under dry sliding-wear test. The experimental results show that the partially dissolved WC particles are uniformly distributed in both coatings produced with circular spot and wide-band spot, respectively, and the microstructures consist of WC and M 23 C 6 carbides and γ-(Ni, Fe) solid solution matrix. However, due to Fe dilution, the two coatings have different microstructural characteristics, resulting in different hardness and wear resistance. The wide-band spot laser prepared coating shows better performance than the circular spot laser prepared coating. [ABSTRACT FROM AUTHOR]

In this study, particle and short fiber-reinforced titanium matrix composite coatings are prepared via laser in situ technique using (0.5 and 50 μm) TiB2 and Ti powder as cladding materials. The microstructure and properties of the composite coatings are studied, and the changing mechanism of the microstructure is discussed. The results reveal that particle agglomeration is prone to appear with using fine TiB2 particles. Decomposition of the particles preferentially occurs with using coarse TiB2 particles. The cracks and pores on the surface of the coating are formed at a lower laser energy density. With the increase in the laser energy density, cracking on the surface of the coating diminishes, but the coating exhibits depression behavior. The depression extent of the coating using fine TiB2 particle as the reinforcement is much less than that of the coating using coarse TiB2 particle. Moreover, the size of the aggregate and the tendency of cracking can be reduced with the increase in Ti addition. Meanwhile, short TiB fiber bundles are formed by the diffusion mechanism of rod aggregate, and randomly oriented TiB short fibers are formed mainly by the dissolution-precipitation mechanism of fine TiB2 particles. Moreover, the growth of short TiB fibers can be in an alternating manner between B27 and Bf structures. The micro-hardness and wear resistance of the coatings are evidently higher than that of the titanium alloy substrate. The wear resistance of the large size TiB2 coating is higher than that of the small size TiB2 coating under the condition of low load. [ABSTRACT FROM AUTHOR]

Supersonic laser deposition (SLD) is a relatively new coating technique, which combines laser irradiation with cold spray (CS). The focus of this research is on the comparison between the WC/SS316L composite coatings produced by CS and SLD respectively, with respect to deposition efficiency, WC distribution and concentration, interfacial bonding, phases in the microstructures, and tribological properties, thus to highlight the beneficial effects of laser irradiation on the composite coating produced by cold spray process. The experimental results show that deposition efficiency, WC concentration and interface bonding of the composite coating can be improved by laser irradiation due to the softening of both powder particles and substrate. The SLD composite coating has the same phases as the CS coating does because of the relatively low heat involved in this process. The high concentration and strong interfacial bonding of WC particles in the SS316L matrix significantly improve the tribological properties of the SLD composite coating. [ABSTRACT FROM AUTHOR]

Although cold spray process has many unique advantages over other coating techniques, it has difficulties in depositing hard materials. This article presents a study in the beneficial effects of laser irradiation on the fabrication process of diamond/Ni60 composite coating using cold spray. The focus of this research is on the comparison between the composite coatings produced with laser cladding (LC) and with supersonic laser deposition (SLD), with respect to diamond graphitization and tribological properties, thus to demonstrate the beneficial effects of laser irradiation on the cold spray process. The influence of deposition temperature on the coating characteristics, such as deposition efficiency, diamond volume fraction, microstructure and phase is also investigated. The tribological properties of the diamond/Ni60 composite coating produced with SLD are determined using a pin-on-disc tribometer, along with the diamond/Ni60 coating produced using LC with the optimal process parameters for comparison. The experimental results show that with the assistance of laser irradiation, diamond/Ni60 composite coating can be successfully deposited using cold spray; the obtained coating is superior to that processed with LC, because SLD can suppress the graphitization of the diamond particles. The diamond/Ni60 composite coating fabricated with SLD has much better tribological properties than the LC coating. [ABSTRACT FROM AUTHOR]

A uniform Ni-P-Al2O3 electroless plating layer was produced on medium carbon steel and then scanned by high-power continuous wave CO2 laser beam. The entire coating is divided into three regions: laser-strengthened region, transition zone, and heat-affected zone. The strengthened coating shows good performance characterized by uniform components and refined microstructures. The main phase is comprised of Ni3P with some non-equilibrium phases. The reinforced particles, Al2O3, are homogeneously dispersed in the coating. Its abrasive resistance also increases because of the Al2O3 particles. [ABSTRACT FROM AUTHOR]

Abstract: Different laser surface hardening techniques, such as laser alloying and laser solution strengthening were adopted to perform modification treatment on the local region of inset edge for 2Cr13 and 17-4PH steam turbine blades to prolong the life of the blades. The microstructures, microhardness and anti-cavitation properties were investigated on the blades after laser treatment. The hardening mechanism and technique adaptability were researched. Large scale installation practices confirmed that the laser surface modification techniques are safe and reliable, which can improve the properties of blades greatly with advantages of high automation, high quality, little distortion and simple procedure. [ABSTRACT FROM AUTHOR]

Abstract: The Ni-P-nano Al2O3 plating layer was prepared on 45 steel by composite electroless deposit, and then hardened by pulse Nd:YAG laser. The surface morphology, microstructure, phase composition, and hardness were investigated respectively. The results show that there is a firm metallurgical bonding between the treated layer and the substrate. Hard phases such as Al5FeNi, FeNi and Fe0.64Ni0.36 form on the surface of composite electroless deposit layer after laser treatment, which contributes to the hardening of coating through fine-crystal strengthening and dispersion strengthening. The hardness of laser treated layer is 4.5 times higher than that of the substrate. [ABSTRACT FROM AUTHOR]

One of the most commonly applied methods of joining dissimilar materials is gluing. This could be mainly attributed to the applicability of this technique in various industries. The article presents a method of material surface treatment, which increases the shear strength of adhesive joints for lightweight metals such as aluminum with plastics. For this purpose, laser surface microstructuring was performed on each of the selected construction materials. As a result of the performed treatment, the active surface of the glued area was increased, which increased the adhesive strength. The picosecond laser with UV radiation used in the research is TruMicro 5325c with which material can be removed as a result of the cold ablation phenomenon. The applied parameters of the laser device did not cause thermal damage to the surface of the microstructured materials, which was confirmed by microscopic examination. Laser micromachining did not deteriorate the degree of wetting of the tested materials, either, as was confirmed by the contact angle and surface energy measurements with the use of water as the measuring liquid. In investigated cases of microstructure types, the presented method significantly increased the shear strength of the joints formed, as demonstrated by the presented strength test results. Research has shown that created joints with microstructure made according to the described method, are characterized by a significant increase in strength, up to 376%, compared to materials without microstructure. The presented results are part of a series of tests aimed at selecting the operating laser parameters for the implementation of geometric shapes of microstructures which will increase the strength of adhesive joints in selected materials. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanotube was used to carburize the surface of medium carbon steel and mild steel, respectively, by means of laser surface remelting. The slurry of carbon nanotube of ethanol was coated on the surface of the materials prior to laser irradiation. Microstructures, microhardness and wear property of the surface layers treated by different laser performance parameters were studied. Graphite coating was also used for carburizing. The results showed that both carbon nanotube and graphite were dissolved in the surface molten layer, leading a carburized hardening layer on the surface of the substrate. However, different microstructures formed in the carburizing layers, depending mainly on the type of carburization materials, carbon nanotube or graphite. The carbon nanotube hardening layer exhibits a little higher hardness than the graphite hardening layer. The carburized layer greatly increases the wear resistance of the base material. [Copyright &y& Elsevier]

Abstract: Medium carbon steel coated with carbon nanotubes was surface treated by a continuous wave CO2 laser beam. The surface remelting layer formed a gradually distributed microstructure of hypoeutectic, eutectic and hypereutectic from the interface of the heat-affected zone (HAZ) and the cladding layer to the top surface of the cladding layer. The microstructure and hardness of the laser-affected zones were studied as a function of the laser beam parameters. The results show that the carbon nanotubes considerably decomposed and dissolved in the molten surface and strongly carburized the cladding layer. The microhardness of the cladding layer and the HAZ decreased with increasing the laser energy of per unit area. Compared with that of the substrate, the microhardness of the cladding layer was considerably increased, reaching 900–1000 HV200, the HAZ was also significantly hardened. The wear resistance of the cladding layer was greatly increased compared with the substrate, the medium carbon steel. [Copyright &y& Elsevier]

The supersonic laser deposition (SLD) of diamond/Cu composite powder is studied over a range of laser power. The deposition efficiency, coating microstructure, cohesive/adhesive bonding, phase composition, micro-hardness, and tribological property of the diamond/Cu composite coating are investigated. The results indicate that, as laser power is increased, deposition efficiency initially increases and then declines. The diamond particles distribute uniformly in the composite coating. Due to the increase of velocity ratio and total energy by laser irradiation, the cohesive/adhesive bonding of the composite coating is improved. The composite coating can preserve the phase composition of the origin powders due to the relatively low heat input during the SLD process. Slight oxidation of the Cu powder can be detected in the coatings prepared with high laser power, which has adverse effects on material deposition. The SLD-diamond/Cu composite coating has superior wear-resistance because of low friction coefficient, high micro-hardness, and uniformly distributed diamond particles. [ABSTRACT FROM AUTHOR]

Supersonic laser deposition (SLD) is a relatively new material deposition technique, which combines laser irradiation with cold spray (CS). The solid-state manufacturing of continuous and dense WC/Stellite-6 composite coatings was achieved by SLD in this study. The comparison between the WC/Stellite-6 composite coatings produced by SLD and laser cladding (LC) respectively was conducted with respect to microstructure, phase composition, microhardness, cracking susceptibility, and tribological behaviors, thus to elucidate the role of laser irradiation in the SLD process. The experimental results show that the SLD coating has fewer defects, higher WC content, lower cracking susceptibility and better wear-resistant performance than the counterpart prepared by LC, which benefits from the preservation of microstructures and phase compositions of the feedstock materials due to the relatively low heat involved in SLD process. Moreover, due to the additional heat provided by laser irradiation, the bonding mechanism in SLD evolves from dominant mechanical bonding in CS to coexistence of mechanical and metallurgical bonding. [ABSTRACT FROM AUTHOR]

Supersonic laser deposition (SLD) process, as a hybrid coating technique, which combines the benefits of both cold spray (CS) and laser irradiation, is a relatively new trend in the field of laser processing. The composite powder of Ni60 alloy powder mixed with diamond particles is deposited on medium carbon steel (AISI 1045 steel) substrate. Two sizes of diamond particles are used respectively in the composite coating. The diamond/Ni60 composite coating specimens prepared by SLD process are studied using scanning electron microscope (SEM), energy dispersive spectrum (EDS) and Raman spectra. The microstructures and interface bonding between the particles and Ni60 matrix are examined using indentation test and SEM. The hardness and tribological properties of the composite coatings are evaluated under Vickers indentation test and pin-on-disc wear test, respectively. The results show that the diamond/Ni60 composite coatings without graphitization of diamond exhibit better tribological properties, the smaller size of diamond is better than the larger one in the composite coatings for wear resistance. This research also demonstrates that SLD technique can deposit hard diamond/Ni60 composite on steel substrate successfully, which cannot be achieved via CS technique. [ABSTRACT FROM AUTHOR]

We demonstrate a laser annealing method for the rapid growth of high-quality Bi 2 Te 3 thin films. The effects of laser energy density on the microstructure, surface chemistry and crystalline phase of Bi 2 Te 3 thin films were systematically investigated. The laser-annealed Bi 2 Te 3 thin films exhibit superior thermoelectric performance, with their Seebeck coefficients are around 30% higher than that of thermally annealed Bi 2 Te 3 thin films. Rapid formation of high-quality stoichiometric Bi 2 Te 3 thin films by laser annealing paves the path for the development of high-performance thermoelectric devices. [Display omitted] • Fast growth of high-performance Bi 2 Te 3 thin films at room temperature is achieved using a laser annealing method. • Formation of Bi 2 Te 3 can be completed in 10 s by laser annealing due to its fast heating and cooling feature. • The thermoelectric power factors of laser-annealed thin films are 30% higher than that of thermally annealed thin films. • The crystalline structure and phase purity extensively affects the thermoelectric performance of Bi 2 Te 3 thin films. Bismuth telluride, (Bi 2 Te 3), is of great scientific and technical importance due to its excellent thermoelectric performance near room temperature. However, deposition of Bi 2 Te 3 thin films suffers from composition deviation due to preferential loss of Te at a high-temperature deposition environment. We demonstrated a fast and efficient laser annealing method to synthesize high-quality stoichiometric Bi 2 Te 3 thin films at room temperature from Te/Bi stacking films. The production rate of Bi 2 Te 3 was around 180 times higher than conventional thermal annealing. The formation of Bi 2 Te 3 thin films was studied with respect to annealing laser energy density. Bi 2 Te 3 thin films with an Bi:Te atomic ratio of 2:3 were achieved at an annealing laser energy density of 6.6 mJ/cm2. The structural, chemical, and thermoelectric performance of laser-annealed films were compared with conventional thermally annealed films. The Seebeck coefficient of laser-annealed films reached −167 µV/K, which was1.3 higher than that of thermally annealed films, evidencing the superiority of the laser annealing method in producing high quality Bi 2 Te 3 stochiometric films. Rapid growth of stoichiometric Bi 2 Te 3 thin films by laser annealing holds great promise for the development of high-performance thermoelectric devices. [ABSTRACT FROM AUTHOR]

• A multi-scale cellular automaton-Eulerian multiphase model is employed to predict the microstructure during the laser directed energy deposition of Inconel 718. • The evolution of grain structure and dendritic structure during the solidification of the whole melt pool is realized. • A complex microstructure evolution mechanism including the epitaxial growth of dendrites from the substrate, heterogeneous nucleation, competitive growth between epitaxial columnar grains, nucleated columnar grains and equiaxed grains was presented. A multi-scale cellular automaton-Eulerian multiphase model is employed to predict the dendritic and grain structure during the laser directed energy deposition of Inconel 718. Simulated transient temperature histories form the macro-scale Eulerian multiphase model are used as input data to the micro-scale microstructure simulation. A complex microstructure evolution mechanism including the epitaxial growth of dendrites from the substrate, heterogeneous nucleation, competitive growth between epitaxial columnar grains, nucleated columnar grains and equiaxed grains was presented, and the influence of the transient thermal history on the primary dendrite arm spacing is discussed. By comparing the simulated solidification microstructure of the melt pool with the experimental results, the accuracy of the coupled model was verified. The results show a reduction in the primary dendrite arm spacing from 12.8μm to 8.3μm from the bottom to the top of the melt pool. According to the aspect ratio of the grains in the melt pool, the top area has 40% equiaxed grains and 60% columnar grains, while the bottom area has 8% equiaxed grains and 92% columnar grains. [ABSTRACT FROM AUTHOR]

The influence of the Ti alloy substrate (α, β, α + β) on the anodic oxidation process was studied. The surface morphology, composition and crystalline structure were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). It was shown that the surface morphology and crystalline structure of anodic oxide films were considerably affected by the Ti alloy substrate. The surface morphologies of the oxide films retain their matrix microstructure characteristics. The oxide film on the residual β phase contains a trace amount of V, Zr, Mo element for TA15. Compared to the secondary α phase, the β phase has a higher degree of oxidation for TB6. The oxide film has the higher Al content on the secondary α phase, while the oxide film formed on β-phase has the higher V content. The XPS results show that the Al, Mo, V, Zr alloy elements of TA15 are involved in anodic oxidation and exist as Al 2 O 3 , MoO 3 , V 2 O 5 , ZrO 2 . Likewise, the Al, V alloy elements of TB6 are involved in anodic oxidation and exist as Al 2 O 3 , V 2 O 5 , but Fe element is not involved in anodic oxidation. The anodic oxide films are partly crystallized and mainly amorphous for the three kinds of titanium alloys. The TA15 anodic oxide film has the highest crystal content, and TB6 has the least. [ABSTRACT FROM AUTHOR]

• SLD coating has significantly lower cumulative mass loss and mass loss rate. • Grain size of the SLD coating is smaller than that of the LC coating. • Severe dilution has observed for the LC coating while it is negligible for the SLD specimen. • The average microhardness of the SLD coating is higher than that of the LC coating. • The pores formed due to mechanical bonding in SLD coating are initial cavitation position. Stellite-6 coatings were deposited on 17-4 PH stainless steel substrate by supersonic laser deposition (SLD) and laser cladding (LC) to improve cavitation resistance of the substrate. The microstructural characteristics of the as-deposited coatings were analyzed on the basis of OM, SEM, EBSD, XRD, Vicker's hardness and nano-indentation results. The cavitation erosion performances in 3.5 wt% NaCl solution were comparatively investigated by a vibratory apparatus for the coatings prepared by SLD and LC technologies. The underlying mechanisms for differences of cavitation behavior between these two samples were elucidated in terms of grain size, dilution level, phase composition, hardness, elastic modulus and topographical features of the worn surfaces. Results show that SLD coating has finer grain, lower dilution and higher ratio of hardness to modulus. By analyzing the eroded surfaces, it is found that the pores formed due to mechanical bonding between particles in SLD coating are the priority position of cavitation where bubbles nucleate, grow and collapse. Repeated impact force from bubble collapse produces cracks and makes cracks propagation, leading to particle detachment and finally material removal. Although the porosity of SLD coating is higher than that of LC coating, its content is only less than 0.4%. Therefore, the negative effect of porosity is weaker than the positive effect of grain refinement, low dilution ratio and high hardness on cavitation performance. Consequently, SLD coating has better cavitation resistance than LC coating. [ABSTRACT FROM AUTHOR]

• Severe elemental micro-segregation occurs in as-deposited Inconel 718 alloy. • Laves phase disappears and recrystallization takes place after solution treatment. • 1100STA specimen has better hot corrosion resistance than DA and as-deposited specimens. • As-deposited Inconel 718 has poor resistance due to the segregation of Nb and Mo. In this research, the hot corrosion behavior of laser deposited Inconel 718 alloy under different heat treatment conditions (solution plus aging, direct aging and as-deposited) is investigated in a salt mixture of Na 2 SO 4 (87.5 wt.%) + NaCl (5 wt.%) + NaVO 3 (7.5 wt.%) at 650 °C. The weight changes of the Inconel 718 specimens that have experienced different heat treatments are measured during the hot corrosion experiments and the data of the weight changes are used to determine the kinetics of the hot corrosion. Field emission scanning electron microscope (FE-SEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) are employed to characterize the corrosion products of the specimens, thus the corrosion mechanisms are analysed. It is shown that the hot corrosion kinetic of the as-deposited Inconel 718 alloy follows a parabolic law. The element mapping results of the corroded surfaces reveal that the corrosion products of as-deposited Inconel 718 include two distinct layers, of which the outermost layer is mainly composed of Ni 2 CrO 4 , Cr 2 O 3 and Fe 3 O 4 , while the inner layer contains Ni 3 S 2. The laser deposited Inconel 718 alloys with different heat treatments behave differently in the hot corrosion. The hot corrosion performance of the solution treated specimens is better than that of the directly aged specimens, while the latter has better hot corrosion resistance than the as-deposited specimens. According to the hot corrosion test results and theoretical analyses, the hot corrosion behavior of as-deposited Inconel 718 alloy with different heat treatments in the salt mixture solution is closely related to basic fluxing mechanism, sulphidation and oxidation as well. [ABSTRACT FROM AUTHOR]

High-performance integrated additive manufacturing with laser shock peening (LSP), is an innovative selective laser melting (SLM) method to improve mechanical properties, and refine microstructure in the surface layer of metallic components. Phase, residual stress distribution, surface micro-hardness, tensile properties and microstructural evolution of SLMed and SLM-LSPed specimens in horizontal and vertical directions were examined. In particular, typical microstructural features in the surface layer were characterized by transmission electron microscopy (TEM) observations. Results indicated that surface micro-hardness subjected to massive LSP treatment had significantly improved, tensile residual stress was transformed into compressive residual stress by LSP-induced plastic deformation, and both SLMed specimens in two directions exhibited a good combination of the ultimate tensile strength (UTS) and ductility. Meanwhile, high-density dislocations and a large number of mechanical twins were generated in the coarse α′ martensites by laser shock wave (LSW), and gradually evolved into refined α′ martensites. Furthermore, according to the included angle between LSW and the deposited plane, two kinds of LSW-induced atomic diffusion processes at the interfaces between both adjacent deposited layers were presented, and the influence mechanisms of the included angle between LSW and the deposited plane on tensile properties of both SLM-LSPed specimens were revealed. The hybrid additive manufacturing technology combined SLM with LSP realizes the high-efficiency and high-quality integrated manufacturing of the formed metallic components for practical applications. Image 1 • LSP was combined with SLM to realize the integrated additive manufacturing. • LSP generated compressive residual stress in surface layer of SLMed specimens. • LSW generated a good combination of UTS and ductility of both SLMed specimens. • Two kinds of LSW-induced atomic diffusion processes at interfaces were presented. • Influence mechanisms of LSP and BD on tensile properties were revealed. [ABSTRACT FROM AUTHOR]