Search Results (459)

To investigate the hot deformation characteristics of the Al–10Mg–3Zn alloy, a series of hot compression tests was carried out using a Gleeble-3500 simulator. The experimental matrix covered temperatures of 300–450 °C and strain rates from 0.001 to 10 s⁻¹. The true stress–strain curves were obtained and the hot processing map of the alloy was constructed based on the Dynamic Material Model principle. The multi-objective optimization of the extrusion process parameters was performed using the response surface method. The results showed that the flow stress of Al–10Mg–3Zn alloy increased with the increase in the strain rate and decreased with the increase in the deformation temperature, indicating that the alloy had a positive strain rate sensitivity. A strain-compensated Arrhenius constitutive model and a hot processing map of Al–10Mg–3Zn alloy were established based on the temperature-corrected data; here, the optimal temperature range and strain rate range for hot processing were specified. The optimal extrusion process parameters, determined by the response surface method, were as follows: billet temperature of 400 °C, extrusion speed of 0.20 mm/s, and ingot length of 350 mm. With this parameter combination, the simulation predicted an extrusion load of 73.29 MN, a velocity deviation of 24.96%, and a cross-sectional temperature difference of 9.48 °C for the profile. The predicted values from the response surface method were highly consistent with those from the finite element simulation. The optimized process parameters significantly reduced the extrusion load of the profile. Full article

Porosity formation due to solidification shrinkage and inadequate liquid metal feeding during the casting of Sn-0.3Ag-0.7Cu (SAC0307) is a critical issue that impairs quality and subsequent processing. However, the opacity of the casting process often obscures the quantitative relationships between process parameters and defect formation, creating a significant barrier to science-based optimization. To address this, the present study utilizes finite element method (FEM) analysis to systematically investigate the influence of pouring temperature (PCT, 290–390 °C) and interfacial heat transfer coefficient (HTC, 900–5000 W/(m²·K)) on this phenomenon. The results reveal that PCT exerts a non-monotonic effect on porosity by modulating the solidification mode, which governs the accumulation of dispersed microporosity. In contrast, HTC plays a critical role in determining porosity morphology by controlling both the solidification rate and mode. Consequently, an optimal processing window was identified at 350 °C PCT and 3000 W/(m²·K) HTC, which significantly enhances interdendritic feeding and improves the ingot’s internal soundness. The efficacy of these optimized parameters was experimentally validated through macro- and microstructural characterization. This work not only elucidates the governing mechanisms of solidification quality but also demonstrates the value of numerical simulation for process optimization, offering a reliable scientific basis for the industrial production of high-quality SAC0307 alloys. Full article

The quantity, size, and distribution of non-metallic inclusions in High-Strength Low-Alloy (HSLA) steel critically influence its service performance. Conventional detection methods often fail to adequately characterize extreme inclusion distributions in large-section components. This study developed an integrated full-process inclusion analysis system combining high-precision motion control, parallel optical imaging, and laser spectral analysis technologies to achieve rapid and automated identification and compositional analysis of inclusions in meter-scale samples. Through systematic investigation across the industrial process chain—from a dia. 740 mm consumable electrode to a dia. 810 mm electroslag remelting (ESR) ingot and finally to a dia. 400 mm forged billet—key process-specific insights were obtained. The results revealed the effective removal of Type D (globular oxides) inclusions during ESR, with their counts reducing from over 8000 in the electrode to approximately 4000–7000 in the ingot. Concurrently, the mechanism underlying the pronounced enrichment of Type C (silicates) in the ingot tail was elucidated, showing a nearly fourfold increase to 1767 compared to the ingot head, attributed to terminal solidification segregation and flotation dynamics. Subsequent forging further demonstrated exceptional refinement and dispersion of all inclusion types. The billet tail achieved exceptionally high purity, with counts of all inclusion types dropping to extremely low levels (e.g., Types A, B, and C were nearly eliminated), representing a reduction of approximately one order of magnitude. Based on these findings, enhanced process strategies were proposed, including shallow molten pool control, slag system optimization, and multi-dimensional quality monitoring. An intelligent analysis framework integrating a YOLOv11 detection model with spectral feedback was also established. This work provides crucial process knowledge and technological support for achieving the quality control objective of “known and controllable defects” in HSLA steel. Full article

Improved plasticity in superalloy castings minimizes processing defects, reduces stress concentration, and enhances mechanical performance. To obtain the microstructure–plasticity relationship, GH4065A ingots were homogenized at 1140–1200 °C for 5–80 h. Microstructural analysis tracked the evolution of dendritic crystals and precipitates (including η phase, carbides, and borides). Tensile tests were conducted to assess plasticity in terms of elongation and reduction in area. Results show that increasing temperature accelerated dendritic dissolution. While 1140 °C was ineffective for short-term dendrite elimination, temperatures of 1160–1200 °C achieved near-complete dissolution within 30–60 h. Precipitates evolution was also observed: the η phase dissolved preferentially, while the sizes of carbides and borides gradually decreased, especially at 1200 °C. Electron probe microanalysis confirmed Nb as the most segregated element. With higher temperatures, Nb diffused from microsegregated zones toward homogeneity. Plasticity improved notably when the Nb segregation coefficient was ~1.5 but decreased at ~1. The optimal homogenization parameters were determined as 1180 °C for 15–60 h. This study provides key processing guidelines for GH4065A ingots, supporting enhanced service performance and operational safety of related components. Full article

Extrusion of AlZnMgCu alloys is associated with a very high plastic resistance of the materials at forming temperatures and significant friction resistance, particularly at the contact surface between the ingots and the container. In technological practice, this translates into high maximum extrusion forces, often close to the capacity of hydraulic presses, and the occurrence of surface cracking of extruded profiles, resulting in a reduction in metal exit speed (production process efficiency). The accuracy of mathematical material models describing changes in the plastic stress of a material as a function of deformation, depending on the forming temperature and deformation speed, plays a very important role in the numerical modelling of extrusion processes using the finite element method (FEM). Therefore, three mathematical material models of the tested aluminium alloy were analysed in this study. In order to use the results of plastometric tests determined on the Gleeble device, they were approximated with varying degrees of accuracy using the Hnsel–Spittel equation and then implemented into the material database of the QForm-Extrusion^® programme. A series of numerical FEM calculations were performed for the extrusion of Ø50 × 3 mm tubes made of 7075 aluminium alloy using chamber dies for two different billet heating temperatures, 480 °C and 510 °C, and for three different material models. The metal flow was analysed in terms of geometric stability and dimensional deviations in the wall thickness of the extruded tube and its surface quality, as well as the maximum force in the extrusion process. Experimental studies of the industrial extrusion process of the tubes, using a press with a maximum force of 28 MN and a container diameter of 7 inches, confirmed the significant impact of the accuracy of the material model used on the results of the FEM numerical calculations. It was found that the developed material model of aluminium alloy 7075 number 1 allows for the most accurate representation of the actual conditions of deformation and quality of extruded tubes. Moreover, the material data obtained on the Gleeble simulator made it possible to determine the limit temperature of the extruded alloy, above which the material loses its cohesion and cracks appear on the surface of the extruded profiles. Full article

In this paper, the moving heat transfer boundary method is adopted to establish a three-dimensional solidification microstructure model based on the coupling technology of the cellular automata method (CA) and finite element method (FE), simulate the ingot growth process, and optimize the nucleation parameters. In addition, this study also explored the influence of process parameters such as melting rate, molten pool temperature, and cooling intensity on the solidification structure of ingots, providing a theoretical basis for process optimization. The results show that the maximum nucleation undercooling degree and the maximum nucleation density have significant effects on different crystal regions of the ingot solidification structure, while the maximum nucleation variance has no obvious effect on the changes in the solidification structure. When the maximum bulk nucleus undercooling degree ${\Delta T}_{v,\max }$ = 4 K, the bulk nucleus standard deviation ${\Delta T}_{v,\sigma }$ = 5 K, and the maximum bulk nucleus density $n_{v,\max }$ = 3 × 107, the simulation results of the solidification structure can be well consistent with the experimental results. With the increase in smelting speed, the number of grains in the ingot structure gradually increases, while the average area of grains gradually decreases. The melting temperature and the intensity of side wall cooling have no obvious influence on the solidification structure of the ingot. Full article

Coordination polymers, particularly those with one- and two-dimensional structures, have garnered significant attention owing to their excellent electrical and optical properties. However, the development of reliable molding techniques for fabricating thin films, pellets, and ingots remains critical for practical applications. In this study, we introduce a novel approach for the direct formation of continuous Ag-coordinated polymer thin films on polymer substrates doped with Ag ions. This process involves ion exchange between the doped Ag ions within the substrate and the protons of the organic ligands, followed by the formation of interfacial complexes between the eluted Ag ions and ligands. Time-resolved analysis revealed that ligand concentration plays a crucial role in thin film formation. Specifically, higher ligand concentrations accelerate nucleation, resulting in the formation of thin films composed of densely packed small-sized crystals. These findings demonstrate the effectiveness of the proposed method for fabricating high-density, uniformly coordinated polymer thin films. Full article

Specimens from commercial and continuously cast A356 ingots have been friction stir-processed, and tensile deformation has been characterized. These two types of ingots have been found to be damaged in the liquid state, but at different levels. In both cases, the microstructure has been refined and homogenized. FSP has been found to improve structural quality by breaking up bifilms. For the commercial ingot, each FSP pass has progressively improved structural quality, as evidenced by an 18 times increase in elongation (from 1.0 to 18.8% after three passes), whereas in the continuously cast ingot, it has taken only one pass for FSP to improve structural quality by doubling elongation (from 10.9 to 21.1%) after which additional passes have not resulted in further improvement. Analysis of tensile deformation behavior has shown that all FSPed specimens exhibit a distinct Stage III work hardening, as modeled by Kocks and Mecking. Through the analysis of tensile deformation behavior, it has been hypothesized that improvement in elongation and structural quality with FSP may not be solely attributed to the refinement of Si particles. Full article

This study investigates the Fe₂₂Ni₁₆Co₁₉Mn₁₂Cr₁₆P₁₅ alloy designed to enhance glass-forming ability. The alloy was synthesized by arc melting and examined using infrared thermography, differential scanning calorimetry (DSC), scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), and X-ray diffraction (XRD). Thermographic measurements revealed a temperature arrest at ~1007 K associated with eutectic crystallization, accompanied by contraction visible as a flattened ingot surface. DSC confirmed the dominant eutectic transformation (−170.7 J/g). Compared with the previously studied Fe₂₂Ni₁₆Co₁₉Mn₁₂Cr₁₆P₁₅ alloy, this composition showed a simplified transformation sequence and a larger eutectic fraction. DSC of melt-spun ribbons demonstrated a three-step crystallization (659 K, 699 K, 735–773 K, completion ~820 K) with a total enthalpy of 180.4 J/g. The broad crystallization interval (ΔTc ≈ 161 K) indicates enhanced thermal stability compared with simpler Ni–P or Fe–Ni–P–C alloys. SEM/EDS observations revealed eutectic colonies with predominantly rod-like morphology and chemical partitioning in inter-colony regions, favoring precipitation of transition metal phosphides. XRD confirmed four crystalline phases (Fe–Ni, CrCoP, Ni₃P, MnNiP) in ingots, while ribbons exhibited a fully amorphous structure. These findings demonstrate that Fe₂₂Ni₁₆Co₁₉Mn₁₂Cr₁₆P₁₅ possesses good glass-forming ability but forms multiple phosphides under slower cooling. Precise cooling control is thus essential for tailoring its amorphous or crystalline state. Full article

Zirconium belongs to the group of critical rare metals and is primarily used in industry. Its most important application, as the basis for specialized alloys, is in nuclear reactors, owing to its exceptionally very low thermal neutron absorption cross-section. Based on theoretical and experimental investigation, the potential for removing metallic (Al, Ti, Hf, V, Fe, Cr, Cu, Ni) and non-metallic (O, C) impurities from technogenic zirconium during electron beam melting (EBM) was assessed. The influence of temperature (ranging from 2350 K to 2750 K) and refining duration (10, 15, and 20 min) under vacuum conditions (1 × 10⁻³ Pa) was investigated concerning the degree of impurity removal, the microstructure, and the micro-hardness of the resulting ingots. It was established that under optimal EBM conditions for technogenic zirconium (T = 2750 K, τ = 20 min), the total refining efficiency reached approximately 87%, and the achieved Zr purity was 99.756%. Among the impurities present in the technogenic zirconium, the lowest removal efficiencies were recorded for Al (54.90%) and Cr (88.89%), with the lower refining efficiency for Al influencing the microstructure and micro-hardness of the ingots produced after EBM. Full article

The simulation of solidification microstructures of cast alloys is crucial to the integrated “process–microstructure–property” numerical simulation. In order to verify the accuracy of the solidification microstructure simulation results, the solidification microstructures of WE54 alloy under both metal mold casting (MMC) and sand mold casting (SMC) conditions were simulated using the CAFE (Cellular Automaton–Finite Element) method, and the simulation results were validated experimentally. First, the effects of microstructure simulation parameters on the results were investigated, including nucleation density (n), nucleation undercooling (ΔT), and dendrite tip growth kinetics parameters (a₂, a₃). The results showed that, with the maximum surface nucleation undercooling (ΔT_s,max) kept constant, increasing the maximum volume nucleation undercooling (ΔT_v,max) significantly increases the proportion of columnar grains in the ingot structure. Moreover, when nucleation parameters remain constant, increasing a₂ and a₃ leads to expansion of the columnar grain zone. Secondly, numerical simulations of the solidification microstructure of WE54 alloy under different solidification conditions were carried out. The results indicated that as the cooling rate increases, the grain structure of the ingot becomes significantly refined, and the proportion of columnar grains decreases notably. Based on these findings, the simulation parameters suitable for simulating the solidification process and microstructure of MMC and SMC WE54 alloy were determined. Simulations of the temperature field and solidification microstructure were performed and compared with experimental results. Full article

Metal-based materials, pivotal for industrialization and technological progress, confront the long-standing issue of high thermal expansion, which limits their application in advanced scenarios. With a century-long research history, negative thermal expansion materials, particularly those in intermetallic compounds, offer promising solutions for regulating thermal expansion. Here, we investigate polycrystalline TbCoSi₂ ingots, revealing a notable 3% in-plane shrinkage from 223 K to 298 K induced by structural phase transitions. Temperature-dependent XRD and Rietveld refinement identify a low-temperature Pbcm space group structure, and the drastic a-axis shrinkage during the phase transition drives the in-plane contraction. Macroscopic magnetic measurements and first-principles calculations reveal an antiferromagnetic structure below 13.7 K, with magnetic and structural phase transitions being independent. These findings present a metal-based weakly magnetic material for precise thermal expansion control, particularly in the uniaxial direction. Full article

When it comes to developing new titanium alloys for biomaterials, β metastable alloys have been gaining the most attention from researchers, as they have a lower elastic modulus and the microstructure can be altered by adding other elements and heat treatments (HT), which makes the material a promising biomaterial. The Ti-10Mo-Mn alloys were melted in an arc furnace. After ingot casting, a homogenization treatment (#T) was carried out, followed by the mechanical processing of hot rolling (#1) and subsequent annealing HT (#2). This work aimed to analyze the influence of some HT on the phase constituents, percentages, morphologies, distributions and selected mechanical properties, such as microhardness and elastic modulus in Ti-10Mo-xMn system alloys, ranging from 0 to 8% by weight. The results showed that alloys with low manganese content, classified as metastable, were sensitive to the HT in this study. From 4% manganese, the alloys had a stable β phase and were, therefore, not sensitive to the HT. The hardness of the alloys with 0 and 2% manganese remained high, possibly due to the presence of the omega phase. The elastic modulus increased from the hot rolling condition (#1) to annealing condition (#2) in all compositions. The Ti-10Mo-2Mn#1 alloy stood out among the alloys studied. It showed the lowest elastic modulus (~87 GPa), making it suitable for use as a biomaterial. Full article

The objective of this study was to develop novel alloys of the Ti-15Nb-xTa system (x = 0, 10, 20, and 30 wt.%) and to evaluate the effect of tantalum addition on the structure, microstructure, hardness, and elastic modulus for biomedical applications. The ingots were produced using an arc melting furnace under a controlled argon atmosphere. Chemical composition analyses were performed using energy-dispersive spectroscopy (EDS) to determine the alloying element fractions and to conduct chemical mapping. The Thermo-Calc software (https://thermocalc.com/, 4 September 2024) was employed to predict the influence of Ta on the phase transformation temperatures. Structural and microstructural characterizations were performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD patterns enabled the identification of the phases, the relative volume fractions, and the lattice parameters of the unit cells. As mechanical properties, Vickers microhardness and elastic modulus were measured. The results revealed that increasing Ta content decreased the β-transus temperature but increased the melting temperature of the alloys. Structural and microstructural characterizations indicated that the Ti-15Nb alloy consisted of α′ + α″ phases, Ti-15Nb-10Ta of α″ + β phases, Ti-15Nb-20Ta of α″ + β + ω phases, and Ti-15Nb-30Ta of metastable β phase. Hardness and elastic modulus results exhibited similar behavior: the alloy with the highest fraction of the α″ phase (Ti-15Nb-10Ta) displayed the lowest hardness and elastic modulus, whereas the alloy containing the ω phase (Ti-15Nb-20Ta) presented significantly higher values. Among the studied alloys, Ti-15Nb-10Ta stands out due to its low elastic modulus (57 GPa). In vitro cellular assays demonstrated that Ti-15Nb-Ta alloys promote osteoblast proliferation while exhibiting no cytotoxicity. Full article

The industrial production of high-speed steel via continuous casting has been impeded by considerable technical obstacles, due to its high carbon content and fast cooling speed, which predispose it to severe segregation and poor high-temperature plasticity; thus, industrial continuous casting of high-speed steel is virtually nonexistent. In 2022, a curved continuous casting process was successfully applied in the production of M2 high-speed steel; in our previous study, it was found that the carbides were finer and better distributed in the billets by curved continuous casting than those in the billets by ingot casting. The change in carbides in the billets is significant in subsequent processes for M2 high-speed steel produced by curved continuous casting. Therefore, it is necessary to investigate the high-temperature tensile properties of M2 high-speed steel produced by curved continuous casting. In this paper, high-temperature tensile tests were conducted using a GLEEBLE-3500 simulator (DSI, located in New York State, USA) at different temperatures and holding times with a certain strain rate to obtain the tensile strength and reduction of area, and then the morphology of carbides near the fracture surface was observed. The results showed that the tensile strength and reduction of area increased with the increase in temperature at 850 °C to 950 °C, and there existed a temperature range between 950 °C and 1120 °C with good thermoplasticity and a reduction of area from 45% to 50%. In addition, a sharp drop in thermoplasticity below 5% occurred at 1180 °C, which is due to the significant growth of carbides. The zero-strength temperature and plastic temperature were 1220 °C and 1200 °C, respectively. In addition, with the increase in holding time at 1150 °C, the reduction of area increased from 34% to 54%, and the tensile strength decreased from 92 MPa to 70 MPa and then increased to 82 MPa. The best solution for carbides in M2 high-speed steel produced by curved continuous casting occurred when the range of the P_HJ value was about 28.0 to 30.5. With the increase in P_HJ value, the shape of carbides gradually changed from fibrous to short rod-like and blocky during high-temperature diffusion. Full article