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Herein, we propose a method for producing W C composite ceramic coatings on tungsten alloy surfaces using directed energy deposition (DED). Different microstructures of DED single tracks were obtained with different line energy densities. Two parts of DED tracks were discovered, which contained the W C fusion zone and the WC-Ni-Co melting injection zone. The W C fusion zone mainly comprised four typical phases, WC, W 2 C, W, and C(diamond, graphite (D, G)), which were present in the microstructures of the tracks in different combinations. The key factor for determining the microstructure evolution was C content. With higher line energy density, more tungsten alloy melted, which decreased C content in the melt pool. As C content decreased, the composition of the microstructure transformed to C(D, G) + WC + W 2 C → WC + W 2 C → W 2 C + W + a small amount of γ-(Ni, Co). C content gradually decreased from the top to the bottom of the melt pool, resulting in a gradient microstructure transition. The microstructure and property could be tuned by controlling the C content. The hardness was the highest, 2300 HV, at 40.7 at.% C with WC-W 2 C eutectoid. This study provides practical insights for producing coatings on tungsten alloy surfaces with optimized process parameters and for tailoring mechanical properties. • DED W-C composite ceramic material on the surface of W alloy was prepared. • W-C fusion zone and WC-Ni-Co melting injection zone of DED tracks were discovered. • The key factor for determining the microstructure evolution was C content. • The hardness of the microstructure was the highest, 2300 HV, with 40.7 at.% C. [ABSTRACT FROM AUTHOR]

• Elemental distribution and correlation analysis of welded joints was investigated. • Defect-free welding joint with improved performance was obtained with MnN < 20%. • The nitrogen conversion process from powder to molten pool was discussed. • MnN powder started decomposing at 800℃ and produced Mn 4 N and Mn 2 N. The lack of Mn content and the importance of Mn to nitrogen content had been confirmed in this study and the welding of high-nitrogen steel with different proportions of MnN/CrN mixed powders was investigated. The distribution of pore defects in the welds and welding stability were analyzed by the synchronous acquisition of photographs using a high-speed camera, current–voltage curves, and plasma spectra. The nitrogen conversion process from powder to molten pool was studied, and the optimized MnN ratio was obtained by observing the microstructure changes in the weld. CrN powder did not produce intermediate products after melting, and it mixed well with the molten pool after melting/decomposition. Cr of the powder significantly improved nitrogen solubility in the austenite, thereby inhibiting micro pores; no CrN/Cr 2 N precipitates were found in the welds. The addition of Mn increased the austenite ratio; however, the MnN powder started decomposing at 800 ℃ and produced intermediate products Mn 4 N, Mn 2 N and N 2 , forming an unstable arc and keyhole and resulting in more pore defects. Thus, a defect-free welding joint with high tensile strength and toughness was obtained by controlling the proportion of MnN to < 20 wt%. When the proportion of MnN was > 30 wt%, pores were formed, which deteriorated the mechanical properties of the joint. [ABSTRACT FROM AUTHOR]

Shield tunnel muck are usually discarded due to high water content and poor engineering properties, resulting in occupation of land sources and waste of soil sources. Meanwhile, large amounts of industrial waste such as carbide slag (CS) and soda residue (SR) are landfilled with a low reuse rate, which poses a threat to the natural environment. This study aims to improve waste shield tunnel muck using CS and SR and traditional lime, and the improved tunnel muck is expected to be used in subgrade filling to provide a new approach to solve this dilemma. A series of physical, mechanical, subgrade property, and microcosmic tests were conducted on shield tunnel muck improved by CS, SR and lime. The effects of different mixing proportions on the properties of improved tunnel muck were examined. The micro-improvement mechanisms of CS and SR on tunnel muck were explored. Results indicate that the addition of CS or SR can effectively improve the physical and mechanical properties of shield tunnel muck. CS plays a significantly role than SR in improving physical and mechanical properties of tunnel muck. A synergistic enhancement is observed as the combined CS and SR are added, and the optimal mixing proportion of tunnel muck to CS to SR is found to be 100:6:2 with a fixed lime content of 4 %. The alkaline environment created by the synergistic action of CS and SR promotes the dissolution of the active ions in soils, and the generated crystals and gelling products of hydration significant contribute to soil improvement. The tunnel muck improved with appropriate CS or SR content could meet the requirements for light or medium traffic load levels and can be effectively utilized as subgrade filling. • Carbide slag or soda residue enhances tunnel muck's properties significantly. • Mechanical properties plateau in tunnel muck beyond 6 % carbide slag content. • Combined carbide slag and soda residue has a synergistic enhancement. • Optimal mix: tunnel muck, carbide slag, soda residue (100:6:2) with fixed 4 % lime. • Carbide slag / soda residue - enhanced tunnel muck meets subgrade performance norms. [ABSTRACT FROM AUTHOR]

The microstructure and corrosion behavior of Y-modified ZK60 Mg alloy prepared by laser powder bed fusion (LPBF) are studied. By controlling the content of Y, the quantity, distribution, and type of precipitates are regulated, and the corrosion resistance is improved. Specifically, the ZK60 alloy with 1 wt% Y exhibits excellent corrosion resistance, which is mainly due to the formation of a continuous network of rare earth-containing precipitates at the grain boundaries that form corrosion barriers to impede corrosion and induce grain refinement. In addition, the passivation and stability of the surface film are improved after the addition of Y. • The microstructure and corrosion behavior of LPBF-processed ZK60- x Y are studied. • The LPBF-processed ZK60-1Y alloy exhibits excellent corrosion resistance. • Continuous rare-earth precipitates at grain boundaries form corrosion barriers. • The microcracks are suppressed after adding an appropriate amount of Y. [ABSTRACT FROM AUTHOR]

• Corn gluten meal could be texturized by extrusion above 120 °C. • The physicochemical properties of the extrudates varied with extrusion temperature. • Disulfide bonds and other covalent bonds participated in protein cross-linking. • A model of temperature factor on protein reaction for texturization was proposed. Corn gluten meal is a by-product of corn starch production. To extend its application in the food industry, the extrusion of corn gluten meal was conducted, and the effects of temperature (80, 100, 120, and 140 °C) on physicochemical properties and protein structure of the extrudates were investigated. Corn gluten meal was texturized when the extrusion temperature reached 120 °C, and puffed when it reached 140 °C. With an increment of temperature from 120 to 140 °C, the bulk density, particle size, and zeta-potential of extrudates decreased (from 662.0 to 642.5 mg/cm3, 301.0 to 191.3 nm, and 4.82 to 1.52 mV). SDS-PAGE showed that disulfide bonds and other covalent bonds participated in protein cross-linking during extrusion. Thus, a model of temperature factor on protein reaction for texturization was proposed: With increase of extrusion temperature, the protein peptides got more unfolding; more covalent reactions occurred under higher temperature, which could be important for texturization. [ABSTRACT FROM AUTHOR]

In this study, a ZK60 Mg alloy fabricated by laser powder bed fusion (LPBF) is subjected to in-situ aging treatment by preheating the substrate. The effects of preheating temperature on the microstructure, mechanical properties, and corrosion resistance of the LPBF-processed ZK60 alloy are systematically analyzed. The results show that at the preheating temperatures of 35, 90, and 180 °C, the average grain size of the samples does not change much, ranging between 7.0 and 8.2 μm. As the preheating temperature increases, the mechanical properties of the alloy increase. The specimens treated at a preheating temperature of 180 °C exhibit a yield strength (YS) of 201 ± 5 MPa, ultimate tensile strength (UTS) of 291 ± 7 MPa, and elongation (EL) of 14.7 ± 0.8%. This is attributed to the precipitation of a large amount of β' 1 phase in the alloy during the aging state in the LPBF process. However, the corrosion resistance first improves and then deteriorates with the increase in the preheating temperature. Under a preheating temperature of 90 °C, the corrosion resistance is improved due to the reduction in the galvanic corrosion area by the precipitated phases. When the preheating temperature is increased to 180 °C, the precipitated phases and α-Mg form a large number of microgalvanic cells, which increases the active center for corrosion and deteriorates the corrosion resistance. These findings indicate that the desired mechanical properties and corrosion resistance of the LPBF-processed ZK60 alloy can be obtained by selecting an appropriate preheating temperature. • The cracks significantly reduce in LPBF-processed ZK60 alloy by substrate preheating. • The mechanical properties increase with increasing preheating temperature. • The corrosion resistance first improves and then deteriorates. • β' 1 phase is beneficial to mechanical properties but deteriorates corrosion resistance. [ABSTRACT FROM AUTHOR]

A novel Al-14.1Mg-0.47Si-0.31Sc-0.17Zr alloy with a low density of 2.54 g/cm3 and a high tensile strength of 510 MPa was manufactured using selective laser melting (SLM) at 200 W and 500 mm/s. The SLM-processed alloy has the comprehensive characteristics of the 5xxx and 6xxx series Al alloys due to its optimized composition. The formation of equiaxed grains occurred during the SLM process, and the mean grain size was 2.97 μm2 in the as-printed (AP) condition. With a heat treatment (HT) of 325 °C for 4 h, the grain size was nearly unchanged (3.45 μm2), and the tensile strength increased to 571 MPa with the formation of Al 3 (Sc, Zr) and Mg 2 Si nanoparticles. This new AlMgSiScZr alloy has promising prospects for replacing some specialized titanium parts in the future. Image 1 • A novel AlMgSiScZr alloy with low density and high strength was prepared by SLM. • The SLM sample has comprehensive characteristics of 5xxx and 6xxx series Al alloys. • This new alloy is hopeful to replace some specialized titanium parts in the future. [ABSTRACT FROM AUTHOR]

In this paper, the corresponding densification, microstructure, precipitate phase and mechanical properties of Al-14.1Mg-0.47Si-0.31Sc-0.17Zr fabricated by selective laser melting were detailly investigated. The experimental result shows that the densification of SLM specimens increased first and then decreased with energy density. Even at the same energy density, the relative densities of the samples are also different, and the printed sample has a high densification under the condition of low laser power and scanning speed. Two typical microstructures (fine grain zone and coarse grain zone) were formed inside the printed samples due to the formation of Al 3 (Sc, Zr) particles (coherent with the Al matrix) during the solidification process of SLM. As fabricated at 200 W and 500 mm/s, the average grain size of the SLM sample is 2.07 (Y-Z plane) and 1.72 μm (X–Y plane), and the maximum values of nano-hardness and tensile strength were 2.19 GPa and 510 MPa, respectively. The mechanical properties increased due to the combined effect of fine grain strengthening and dispersed distribution of precipitates in Al matrix. With a low density (2.537 g/cm3) and high tensile strength, the components fabricated by this alloy have more extensive spreading values and prospects for applying due to the excellent mechanical performance. [ABSTRACT FROM AUTHOR]

A novel Sc- and Zr- modified 7075 Al alloy with a low microalloying content (0.4 wt% Sc and 0.25 wt %Zr) was designed and the influence of process parameters on the microstructure and mechanical properties of selective laser melting (SLM) samples was systematically analyzed. As the SLM energy input increased, the relative density of block specimens first increased before plateauing. At a high energy density, crack defects disappeared, and the average grain size significantly decreased. For the specimen fabricated at 375 J/mm3, the average grain size was 2.6 μm, which is only 9.8% of the size of samples fabricated at 44 J/mm3. Due to fine grain strengthening, the mechanical properties of the printed specimens were remarkably improved, but the high energy input softened the matrix. Due to these two opposing effects, the compressive strength and nano-hardness of specimens fabricated at 375 J/mm3 were 621 MPa and 1.85 GPa, which are respectively 129.6% and 98.4% of the specimen fabricated at 44 J/mm3. [ABSTRACT FROM AUTHOR]

To explore the microstructure response to repeated sliding of materials showing stress-induced martensitic (SIM) transformation, we have investigated the microstructure evolution of solutionized Ti-51.5 at.% Ni introduced during the dry sliding against the GCr15 sphere at room temperature. It was found that B19′ was the dominant phase in the worn subsurface of solutionized case exhibiting extremely low martensitic transformation start ( M s ) temperature (lower than −120 °C) and reverse transformation finish temperature ( A f = − 3.4 °C), albeit amorphous structure observed in the topmost layer. Remarkably, nanotwins and faulting were experimentally revealed to contribute to the special microstructure. Moreover, particles of R phase were also discovered. The elementary mechanisms illustrated will be essential for the future modelling of the tribologically deformed layer of the alloys. • The microstructure responses of the solutionized Ti-51.5 at.% Ni to sliding wear have been analyzed by TEM. • Martensite (B19′ and R) was retained at room temperature albeit A f = − 3.4 °C. • Amorphisation was ascribed to faulting in B2 and nanotwins accumulation in B19′. [ABSTRACT FROM AUTHOR]