Wire and laser additive manufacturing (WLAM) can produce outstanding mechanical properties of GH3039 nickel-based superalloys. A quantitative rapid phase field model with solute trapping kinetics has been developed during the rapid solidification process, where a range of process conditions are considered in terms of thermal gradients and pulling speeds. Intergranular hot cracking is found to occur at boundaries of tilted columnar dendrite in the GH3039 nickel-based superalloys. The simulations demonstrate that the phase field model considering the interface deflection can represent the dendrite growth during additive manufacturing more realistically. With the aid of numerical simulations, it is determined that dendrite growth morphologies transform from symmetrical columnar dendrite to tilted columnar dendrite as the interface crystallographic deflection is increased, while increasing the deflection angle can lead to uneven composition of material matrix, especially at the columnar dendrite interface. Solute concentrations at the columnar dendrite interface tend to promote hot cracking in additively manufactured Ni-based superalloy.

Fusion welding of Ti-Cu is difficult because of big difference of melting points and formation of brittle intermetallic compounds. Friction stir welding is carried out by solid-state joining, thermo-mechanical stirring, and friction heat. Ti-Cu FSW dissimilar welding can supply a very sound joint area with a few intermetallic compounds. Optimized welding process conditions are essential to obtain suitable microstructure and mechanical properties of welded zones. Different welding speeds affect the evolution of microstructure and mechanical properties due to changes of input heat and internal stored deformation energy. The correlation of microstructure and mechanical properties of Ti-Cu welded zone according to welding speeds were investigated and analyzed. As the higher the welding speed, the lower the heat input and the lower the temperature rise. Ti-Cu 75 has the smallest grain size at 13.9 μm, but the optimum mechanical properties and the integrity of welding were shown in Ti-Cu 50.

A TiC-Mo ₂C-WC-Ni alloy cermet was fabricated by high-energy ball milling (HEBM) and consolidation through spark plasma sintering. The TiC-based powders were synthesized with different milling times (6, 12, 24, and 48 h) and subsequently consolidated by rapid sintering at 1300°C and a load of 60 MPa. An increase in the HEBM time led to improved sinterability as there was a sufficient driving force between the particles during densification. Core-rim structures such as (Ti, W)C and (Ti, Mo)C (rim) were formed by Ostwald ripening while inhibiting the coarsening of the TiC (core) grains. The TiC grains became refined (2.57 to 0.47 µm), with evenly distributed rims. This led to improved fracture toughness (11.1 to 14.8 MPa·m ^1/2) owing to crack deflection, and the crack propagation resistance was enhanced by mitigating intergranular fractures around the TiC core.

The mechanical response of interpenetrating co-continuous composite Al-Si12/SiC3D was described for uniaxial tension and compression. The internal structure of the IPC was examined by optical microscopy and micro-CT. The apparent density and Young’s modulus were assessed theoretically and experimentally. Uniaxial tensile tests were performed using the prismatic samples of dimensions 1 mm × 2 mm × 30 mm. Cylindrical samples of diameters ϕ = 5 mm and height h = 10 mm were subjected to quasi-static uniaxial compressive loading. During tests, the side surfaces of the specimen were observed using a digital image correlation system (DIC) to find strain fields and to monitor the surface cracks development in the complex internal microstructure of the IPC.
The analyzed two-phase ICP was manufactured using ceramic foam SiC infiltrated by alloy Al-Si12. This material finds application in cosmic, airplane, or automobile industries, due to their excellent tribological, heat distribution, and ballistic properties.
Obtained results show different modes of microcracking and fracture of cylindrical and prismatic samples. They indicate the substantial influence of the ceramic skeleton on the behavior of the IPC under uniaxial states of loading. Different modes of damage related to the tension or compression loading were described in detail. The results can find application in the designing process of modern co-continuous IPCs and further development of the numerical models of degradation processes.

This study aimed to develop Fe/Al multilayered metallic/intermetallic composites produced by hot pressing under an air atmosphere. Analyses were carried out on the composite plates made up of alternatively situated sheets of AA1050 aluminum alloy and DN04 low carbon steel, which were annealed at 903 K for 2, 5, and 10 h. Annealing was performed to obtain reaction layers of distinct thickness. The samples were examined using X-Ray diffraction and scanning and transmission electron microscope equipped with an energy-dispersive X-Ray spectrometer. To correlate the structural changes with mechanical properties, microhardness measurements in near-the-interface layers were performed. All the reaction layers grew with parabolic kinetics with η-Al5Fe2 intermetallic phase as the dominant component. After annealing for 5 and 10 hours, a thin sublayer of θ-Al13Fe4 phase was also detected.

In this study, the bio state of the alloy produced in the modified metal injection system was monitored after sintering. A new system operating with high gas pressure, far from the traditional injection model, has been established for material production. In this system, 316L stainless steel powders were molded using a PEG/PMMA/SA polymer recipe. During molding, approximately 60% 316L and 40% binder by volume were used. The samples obtained were sintered at different temperatures (1100-1300°C) after de-binding. Density measurement (Archimedes) and hardness tests (HV1) of the samples were measured as 6.74 g/cm3 and ~285 HV1, respectively. A potentiodynamic corrosion test was applied to monitor the effect of the amount of oxide in the structure of the 316L stainless steel produced. Corrosion tests were carried out in artificial body solutions. The corrosion rate was measured at the level of 17.08×10–3 mm/y. In terms of biocompatibility, a cytotoxicity test was applied to the samples and the life course of the bacteria was monitored. For the 316L alloys produced, the % vitality reached approximately 103%.

Impacts of precursor solution recipe, processing parameters, and pellet thickness on the lithium ionic conductivity of the ceramic materials with perovskite structure of Li _0.3La _0.57TiO _{2 0.3}La _0.57TiO _{2 0.3}La _0.57TiO ₂2 (i.e., TiO ₂ sol) and then Li+ and La+ were added to the colloidal TiO ₂ was on the order of 10-5 S/cm. It also showed that the temperatures corresponding to a full decomposition for Li _0.3La _0.57TiO ₂ is about 750°C and materials start forming perovskite structure when temperature reaches about 900°C and the lithium ionic conductivity gains about 21% increase when the pellet thickness is reduced to about ¼.

Azo dye is widely used in the textile industry since it is cost effective and simple to use. However, it becomes a continuous source of environmental pollution due to its carcinogenicity and toxicity. Various methods had been used to remove the azo dye in solution. One of the famous and frequently used is the Fenton process. The Fenton process is one of the advanced oxidation processes where iron catalysed hydrogen peroxide to generate hydroxyl radical. Treating azo dyes in solution requires a catalyst to enhance the process of degradation. Herein, high entropy alloys (HEAs) have been proposed as a catalytic material to enhance the performance of Fenton process for azo dye degradation. HEAs have been reported as a promising catalyst due to its high surface area. The higher the number of active sites, the higher the rate of azo dye degradation as more active sites are available for adsorption of azo dyes. The results have shown that HEAs can be used as a catalyst to fasten the Fenton reaction since the degradation time is proven to be shorter in the presence of HEAs. The method derived from the result of this study will contribute in treating azo dyes for wastewater management in the Fenton process.

In this study, a research was conducted to recover metallic zinc and pig iron and to improve the purity and the recovery rate through a reduction process for zinc and iron in the byproducts that are generated after steelmaking dust treatment. As the result of the calcination, it was confirmed that Cl (6.06%) and K (3.37%) decreased to Cl (2.75%) and K (0.22%), respectively. For the zinc powder that was recovered with reaction temperature of 1100°C, reaction time of 4 hours, and argon gas of 1L/min as the optimal conditions. The measurement for the purity of zinc was 99.8% and the recovery rate was 92.14%. The melt reduction for recovering pig iron from the residue was reacted under reaction temperature of 1600°C, flux composition (CaO:SiO2) of 1:1, and reducing agent infusion ratio (residue: C) of 14:1, and the pig iron was measured to have a purity of 87.7% and a recovery rate of 91.81%.

Surface melting and alloying of Copper-Nickel (Cupronickel) alloy by preplacing aluminum powder and using tungsten inert gas process (TIG) in shielded atmosphere of argon gas were investigated. Surface melting resulted in the formation of a fairly porous dendritic microstructure. Surface alloying with aluminum resulted in the formation of Al ₂Cu and Al ₄Cu ₉ intermetallic compounds along with Cu-rich matrix and unstable martensitic structure. Surface melting reduced the hardness from 140 HV _0.1 (substrate) to 70 HV _0.1, mainly due to the loss of cold work effect of the initial substrate. On the other hand, surface alloyed zone showed a hardness of 300 HV _0.1, mainly due to the formation of intermetallic compound. Tafel polarization results indicated improvement in corrosion resistance of cupronickel alloy after surface melting and alloying.

An attempt has been made to synthesize the aluminium based ex-situ (Al-SiC) and in-situ (Al-TiB2) formed metal matrix composites with varying weight percentage of reinforcement contents such as 4wt.%, 6wt.% and 8wt.%. Synthesized composites were subjected to a cold extrusion process followed by heat treatment according to the ASTM B 918-01 standards. The mechanical properties of in-situ composites were evaluated as per the ASTM guidelines and compared with ex-situ formed composites and base metal properties. Superior properties were noticed in the in-situ formed composites and the mechanical properties such as yield strength, Ultimate tensile strength (UTS) and Hardness for both ex-situ and in-situ composites were found to increase with increasing the reinforcement addition. Cold extruded Al-8 wt.% SiC composite properties such as hardness, yield strength and UTS are 87 RB, 152 MPa, 216 MPa respectively. Whereas, for Al-8 wt.% TiB2 composite, the corresponding properties are 94 RB, 192 MPa, 293 MPa. The morphology of the composites is analysed by Optical and Scanning Electron Microscopic (SEM) whereas presence of reinforcement particles such SiC and TiB2 along with intermetallic phases Mg2Si and Al5FeSi are confirmed by EDX, XRD and Element Mapping analyses.

Cu-Sn alloys have been known as bronze since ancient times and widely used as electrode materials, ornaments, tableware and musical instruments. Cu-22Sn alloy fabrication by hot forging process is a Korean traditional forged high-tin bronze. The tin content is 22 percent, which is more than twice that of bronze ware traditionally used in China and the West. Copper and tin have a carbon solubility of several ppm at room temperature, making Cu-Sn-C alloys difficult to manufacture by conventional casting methods. Research on the production of carbon-added copper alloys has used a manufacturing method that is different from the conventional casting method. In this study, Cu-22Sn-xC alloy was fabricated by mechanical alloying and spark plasma sintering. The carbon solubility was confirmed in Cu-Sn alloy through mechanical alloying. The lattice parameter increased from A0 to C2, and then decreased from C4. The microstructural characteristics of sintered alloys were determined using X-ray diffraction and microscopic analysis. As a result of comparing the hardness of Cu-22Sn alloys manufactured by conventional rolling, casting, and forging and Cu-22Sn-xC alloy by sintered powder metallugy, B0 sintered alloy was the highest at about 110.9 HRB.

The paper presents a summary of research on the possibility of influencing the state of residual stresses in railway rails by changing the pass design of vertical and horizontal straightener rollers and optimising their distribution on the rail perimeter. The presented results are devoted to the influence of profiled rollers on the level of residual stresses. A wide range of theoretical considerations were carried out based on the use of the finite element method using the commercial Forge software package. In order to verify the results of the theoretical considerations most reliably, a series of “in situ” experiments were conducted in industrial conditions on an existing production line. The tests were carried out on 120 meters long 60E1 railway rails. A significant reduction in the level of residual stresses compared to the standard requirements was achieved.

The effects of different types of balls on spark plasma sintering (SPS) characteristics of high energy ball milled Ti-48wt% Al-4wt% Nd powders were investigated. After ball milling with STS balls and zirconia balls at 800 rpm for 3 h in argon atmosphere, both powders showed shape factors of about 0.8, but their average powder sizes differed respectively at approximately 11 µm and 5 µm. From XRD results, only the peaks of pure Ti, Al and Nd were detected in both powders. The obtained Ti-Al-Nd powders were consolidated by SPS technique at 1373 K for 15 min under a pressure of 50 MPa in vacuum, resulting in high density over 99%. EDS and XRD analyses indicated the formation of binary phases such as TiAl3, TiAl, Ti3Al5, and NdAl3 after SPS in both cases of STS and zirconia balls, while the ternary Ti-Al-Nd phase was detected only in the case of zirconia balls. The size of second phases was slightly smaller in the case of zirconia balls. The microhardness of the sample was 790 Hv with zirconia balls and 540 Hv with STS balls.

The austenitic stability and strain-induced martensitic transformation behavior of a nanocrystalline FeNiCrMoC alloy were investigated. The alloy was fabricated by high-energy ball milling and spark plasma sintering. The phase fraction and grain size were measured using X-ray diffraction. The grain sizes of the milled powder and the sintered alloy were confirmed to be on the order of several nanometers. The variation in the austenite fraction according to compressive deformation was measured, and the austenite stability and strain-induced martensitic transformation behavior were calculated. The hardness was measured to evaluate the mechanical properties according to compression deformation, which confirmed that the hardness increased to 64.03 HRC when compressed up to 30%.

Fixed beds were adopted for removal of organic dye from water by photocatalytic decomposition or adsorption. To this end, macroporous titania or silica micro-particles were synthesized from emulsions as micro-reactors and packed in the bed. During feeding aqueous methylene blue solution, UV light was irradiated for generation of active radicals for removal of dye by photocatalytic decomposition. Porous silica particles were also used as adsorbents in the bed for continuous adsorption of organic dye. For regeneration of the porous titania or silica particles, rinsing with fresh water was carried out before repeated cycles.

The lap joint welding of Al 3003 alloy by stationary shoulder friction stir welding (SSFSW) was performed under the conditions of tool rotation and welding speed, and it was confirmed that the welding was performed under all conditions. The tunnel defects and pores were formed in the weld zone at the lowest tool rotation and welding speed, and it is increased, the weld surface has been improved. At the same tool rotation speed at the welding speed is increased, the grain size was refined in the stir zone (SZ) and thus the hardness increased by about 14% compared to the base metal. The tensile shear strength is measured to be 10 kN or more under most conditions, and in the 4000 rpm with high heat input, the shear tensile strength was measured relatively lower than other conditions due to excessive heat input of the material.

This study was conducted to treat radioactive acidic wastewater, which contained radioactive ⁶⁰Co and ¹⁵²Eu. The wastewater can be generated during a decommissioning project to reduce the volume of radioactive concrete waste from nuclear facilities. With a variety of methods for separating the radioactive nuclides available, we evaluated the separation applicability of the solvent extraction method. From our results, Co and Eu could be easily extracted from the Ca rich wastewater using Cyanex301 (Co extraction (%) 99.8, Eu extraction (%) 99.6) without Ca extraction. On the other hand, Eu could be selectively separated by Cyanex272 (Eu extraction (%) 99.1) without Co and Ca extraction at pH 2~3. Therefore, the extraction method can be tailored according to the target radionuclides present in the wastewater and be selectively applied to the overall treatment process. By extracting radioactive Co and Eu from acidic wastewater to below the discharge criteria, treated wastewater could be regarded as non-radioactive industrial waste, to be economically and easily handled. Moreover, it may be possible to reuse separated Co and Eu for research and industrial applications by realizing waste valorization.

In this study, the effect of calcium treatment on the mechanical properties and fatigue behavior of low carbon steel material is investigated. By applying calcium treatment after aluminum deoxidation for steel cleanliness, the aim is to transform the inclusions into harmless structures and produce cleaner liquid steel. As a result of the study, calcium treated material’s tensile strength slightly increases while fatigue life decreases. SEM studies were conducted to evaluate the results and it was observed that while elongated inclusions were observed as well as spherical shapes in the untreated sample, the inclusions generally had a spherical shape in the calcium treated sample. After the steel cleanliness process, the mechanical properties of the samples were improved. The tensile strength of the calcium treated sample increased slightly. However, a significant decrease in fatigue strength was observed depending on brittle inclusions that occur as a result of the calcium treatment process.

In this study, a rare earth composite precipitation (NaREE(SO ₄) ₂H ₂O, REE: Ce, La, Nd, Pr) powder was prepared from spent nickel hydride batteries, and cerium hydroxide was separated from its constituent rare earth elements. As Ce(OH) ₃ can be oxidized more easily than other rare earth elements (La, Nd, and Pr), Ce ³⁺ was converted to Ce ⁴⁺ by injecting air into the leachate at 80°C for 4 h. The oxidized powder was leached using sulfuric and hydrochloric acids. Because Ce(OH) ₄ has low solubility, it can be separated from other elements. Therefore, the pH of the leaching solution was adjusted for selective precipitation. To determine the crystalline phase, recovery, and grade of the recovered Ce(OH) ₄, the powders were analyzed using X-ray diffraction, scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy. The grade and recovery rates of the Ce(OH) ₄ powder recovered from the rare earth composite precipitate using sulfuric acid as the solvent were 95% and 97%, respectively, whereas those of the powder recovered using hydrochloric acid were 96% and 95%, respectively.

The forming limit of AZ31 alloy, a representative Mg-Al-Zn-based wrought alloy, and the effect of severe plastic deformation (SPD) by examining the microstructure change caused by dynamic recrystallization led by high temperature and high dislocation density at 300℃ using a biaxial alternate forging (BAF) were investigated in this study. As a result of BAF test for AZ31 Mg alloy, significant cracks on the ends of workpieces occurred after 7 passes. The microstructure of as-extruded specimen showed the non-uniform distribution of the relatively coarse grains and the fine grains considered to be sub-grains. However, as the number of passes increases, the area of coarse grains gradually disappeared and the fine grains became more dominant in the microstructures. The result of tensile test for workpieces with each forging pass showed an increase in strength depending on pass number was shown with a slight increase of elongation. The Electron Backscatter Diffraction (EBSD) results exhibited that, the microstructure showed the presence of coarse grains and twins after only 1 pass, while the grains appeared to be significantly refined and uniformly distributed after 3 pass, at which the strength and elongation began to increase, simultaneously.

This paper presents a method of synthesizing copper powders by electrochemical method with the use of a rotating working electrode. The influence of the rotation speed of the working electrode, the current density, the concentration of copper ions, and the addition of ethylene glycol on the shape, size, and size distribution of the obtained powders were investigated. Properties of the synthesized powders were characterized by scanning electron microscopy (SEM) and X-ray powder diffractometry (XRD). It has been shown that it is possible to obtain copper powders with a size of 1 µm by an electrochemical method using the rotary cathode, in sulphate bath with addition of ethylene glycol as a surfactant. Increasing current density causes a decrease in the average size of the obtained powder particles. The addition of 2.5% of ethylene glycol prevents the formation of dendritic powders. The change in the concentration of copper ions in the range from 0.01 to 0.15 mol/dm3 in the electrolyte did not show any significant effect on the size of obtained particles. However, higher concentrations of copper limiting the presence of dendritic-shape particles. Changing the speed of rotation of the electrode affects both the size and the shape of synthesized copper powder. For the rotational speed of the electrode of 115 rpm, the obtained powders have a size distribution in the range of 0-3 µm and an average particle size of 1 µm. The particles had a polygonal shape with an agglomeration tendency.

This study examined the effects rheological properties of different composition kaolin and kaolin geo-filler in polypropylene composites. Polypropylene composites with varying composition of kaolin geo-filler 0 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, and 10 wt% was prepared and compared with polypropylene composite with raw kaolin. Kaolin is an aluminosilicate based mineral filler was used to prepare geopolymer paste by combining with alkaline activator solution. The polypropylene composite was compounded using a twin-screw extruder and the melt flow index was determined by a constant weight pressure of 2.16 kg at 230°C in 10 min. Knowing the melt flow index is necessary to predict and control the process, the study has demonstrated that the composition of kaolin filler and kaolin geo-filler affects the melt flow, melt density and surface morphology at varies composition. Composites with kaolin geo-filler have demonstrated high melt flow index process and having better distribution and flow.

The hydrogen embrittlement of metals is caused by the penetration and accumulation of hydrogen atoms inside the metal. The failure of the product due to hydrogen embrittlement is delayed in time and does not occur immediately after its manufacture, but several hours, days, or even weeks later. Therefore, the chances of detecting hydrogen embrittlement when checking the quality of the finished product are very slim. The use of high-strength bolts in industry is associated with the risk of hydrogen embrittlement. This phenomenon poses a threat to the safe use of devices by limiting or completely losing the functionality of the bolt joint. Even a low influence of moisture can trigger failure mechanisms.
The article proposes a method for assessing the risk of hydrogen embrittlement for high-strength bolts in class12.9. For this purpose, bolts made of material grade 32CrB4 were prepared and in a controlled manner the grain flow inconsistency was made, leading in extreme cases to the production of the forging lap. To perform the study, the device proposed by the European Assessment Document (EAD) was adapted to the testing of hydrogen embrittlement of threaded fasteners in concrete. The concrete substrate was replaced with metal spacers that were preloaded with a bolt. The use of the wedge distance under the bolt head led to the generation of two stress states – tensile and compressive, which translated into an increased risk of hydrogen embrittlement. After being tested, the bolts were visually and microscopically inspected to assess potential locations for cracks and hydrogen propagation. As a result of the conducted tests, it was found that the prepared test method allows to assess the resistance or susceptibility of the bolt to threats related to hydrogen embrittlement.