Search Results (27)

A method for generally predicting interface chemical bonding at the metal–oxide interface with the interface reaction considered is reported. So far, the interface between pure metal or alloy and 11 oxides—MgO, Al₂O₃, SiO₂, Cr₂O₃, ZnO, Ga₂O₃, Y₂O₃, ZrO₂, CdO, La₂O₃, and HfO₂—without considering the interface reaction, has been discussed and implemented in the free web-based software product InterChemBond (v2022). Now, the number of oxides available for prediction is 83 in total. Among them, 29 oxides are in one stable valence, and the others are multi-valence. The newly developed prediction method considering the interface reaction is additionally implemented in InterChemBond. The principles and formula for predicting interface bonding while considering interface reactions are provided as well as some screenshots of the software. Full article

Semi-solid processes of aluminium alloys, characterised by the coexistence of solid and liquid phases, offer advantages in terms of mechanical properties and fatigue resistance, thanks to the more globular microstructure. Thermodynamic models can be used to analyse the solidification behaviour and to predict the solidification window, ΔT. The CALPHAD method enables the calculation of the phases formed during solidification and the optimisation of alloy composition to meet specific industrial requirements. This study aims to assess how thermodynamic properties in both liquid and solid phases affect the ΔT. Initially, the influence of thermodynamic properties of pure components and interaction parameters was analysed in simplified regular binary systems. To compare these findings with real industrial systems, Al-based alloys were examined. Using available databases, the ΔT was estimated via the CALPHAD method adding alloying elements commonly found in secondary Al-alloys. Finally, the same minority alloying elements were added to Al-Si 8 and 11 wt.% alloys, and the corresponding ΔT were calculated. Cr, Fe, Mg, Mn, and Ti increase the ΔT, while Cu, Ni, and Zn decrease it. The obtained results may serve as a valuable tool for interpreting phenomenological observations and understanding the role of minority elements in the semi-solid processing of secondary Al-Si casting alloys. Full article

This study systematically investigated the effects of the addition of the rare earth element yttrium (Y) on the microstructural evolution, mechanical properties, and corrosion behavior of as-extruded Al-5.6Zn-2.5Mg-1.6Cu-0.20Cr (wt.%) alloy through comprehensive characterization techniques, including X-ray diffraction (XRD), tensile testing, corrosion analysis, and electron microscopy. Microstructural characterization demonstrated that the incorporation of yttrium resulted in significant refinement of secondary phase particles within the as-extruded alloy matrix. Moreover, quantitative analysis revealed a substantial increase in low-angle grain boundary (LAGB) density, dislocation density, and the formation of subgrain structures. Notably, the volume fraction of η′ strengthening precipitates showed a marked increase, accompanied by a corresponding reduction in the width of precipitate-free zones (PFZs) along grain boundaries. Following the T74 aging treatment, the alloy with 0.1 wt.% yttrium addition exhibited a remarkable improvement in intergranular corrosion resistance, with the maximum corrosion depth reduced to 107.8 μm. However, it should be noted that the exfoliation corrosion resistance exhibited an inverse correlation with increasing yttrium content, suggesting a concentration-dependent behavior in corrosion performance. Full article

The formation and evolution of SmCo₅/Sm₂Co₁₇ (1:5_H/2:17_R/H) cellular structures play an essential role in understanding the coercivity of Sm-Co magnets. Herein, the pristine and different elemental-doped 1:5/2:17_R and 1:5/2:17_H interfaces are investigated to evaluate the elemental site preferences, interface configurations, and magnetic properties in Sm₂Co₁₇-type magnets with general alloy elements M (M = Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Al, Si, and Ga). Comparing the calculated results of 1:5/2:17_H with those of the 1:5/2:17_R interface, we found that Cu and Mn always segregate at the 1:5 phase, and Ga elements first appear at the 1:5 phase in 1:5/2:17_H and then change to the 2:17 phase in 1:5/2:17_R. While Ti, V, Fe, Zn, Al, and Si elements always tend to segregate at the 2:17 phase, Ni first segregates at the 2:17 phase in 1:5/2:17_H and then occupies the 1:5 phase of 1:5/2:17_R. The 1:5/2:17_H interface along the c-axis expands about 1.98~3.28%, while the 1:5/2:17_R interface slightly shrinks about 0.04~0.87% after element doping. This suggests that different interface stress behaviors exist for high-temperature and room-temperature phase Sm₂Co₁₇-type magnets. Furthermore, Mn, Fe, and Ga doping improved the saturation magnetization strength. Our results provide new insights into understanding the effect of elemental doping at the interfaces of 1:5_H/2:17_R cellular structures. Full article

The influence of as-cast grain size on recrystallization and the related mechanical properties of Al–Zn–Mg–Cu-based alloys was investigated. Grain sizes ranging from 163 to 26 μm were achieved by adding Ti, Cr and Mn, and ZnO nano-particles, which acted as heterogeneous nucleation sites. A decrease in the as-cast grain size led to a corresponding reduction in the recrystallized grain size from 54 to 13 μm. Notably, as-cast grain sizes below 100 μm provided additional nucleation sites at grain boundaries, allowing for a reasonable prediction of recrystallized grain size. Finer grains also contributed to enhanced mechanical properties, with yield strength increasing as recrystallized grain size decreased without significant loss of elongation. Additional strengthening was observed due to η-precipitates at grain boundaries, further improving the properties of fine-grained sheets. Full article

Increasing demand for functional materials crucial for advancing new technologies has motivated significant scientific and industrial research efforts. High-entropy materials (HEMs), with tunable properties, are gaining attention for their use in high-frequency transformers, microwave devices, multiferroics, and high-density magnetic memory components. The initial exploration of HEMs started with high-entropy alloys (HASs), such as CrMnFeCoNi, CuCoNiCrAlxFe, and AlCoCrTiZn and paved the way for a multitude of HEM variations, including oxides, oxyfluorides, borides, carbides, nitrides, sulfides, and phosphides. In this study, we fabricated the high-entropy oxide (HEO) compound ${\mathrm{B}\mathrm{i}}_{0.5}{\mathrm{L}\mathrm{a}}_{0.1}{\mathrm{I}\mathrm{n}}_{0.1}{\mathrm{Y}}_{0.1}{\mathrm{N}\mathrm{d}}_{0.1}{\mathrm{G}\mathrm{d}}_{0.1}\mathrm{F}\mathrm{e}{\mathrm{O}}_3$ through the solid-state synthesis method. Magnetic measurements at 300 K show ferromagnetic behavior with significant coercivity. At the same time, this novel composition exhibits excellent dielectric properties and shows potential for electronic applications demonstrating that a high-entropy approach can expand the compositional range of rare earth multiferroics and improve the multifunctional properties in multiferroic applications. Full article

Methanol and hydrotreated vegetable oil (HVO) are complementary in the context of achieving ultra-low emission levels via low temperature combustion. HVO is a high-quality fuel fully compatible with compression ignition engines. Standalone methanol combustion is relatively straight-forward according to the Otto principle, with a spark ignited or in conventional dual-fuel (“liquid spark”) engines. These two fuels have by far the largest reactivity span amongst commercially available alternatives, allowing to secure controllable partially premixed compression ignition with methanol–HVO emulsification. This study investigates the corrosion of aluminum, carbon steel, stainless steel, and a special alloy of MoC210M/25CrMo4+SH, exposed to different combinations of HVO, HVO without additives (HVOr), methanol, and emulsion stabilizing additives (1-octanol or 1-dodecanol). General corrosive properties are well determined for all these surrogates individually, but their mutual interactions have not been researched in the context of relevant engine components. The experimental research involved immersion of metal samples into the fuels at room temperature for a duration of 60 days. The surfaces of the metals were inspected visually and the dissolution of the metals into fuels was evaluated by analyzing the fuels’ trace metal concentrations before and after the immersion test. Furthermore, this study compared the alterations in the chemical and physical properties of the fuels, such as density, kinematic viscosity, and distillation properties, due to possible corrosion products. Based on these results, methanol as 100% fuel or as blending component slightly increases the corrosion risk. Methanol had slight dissolving effect on aluminum (dissolving Al) and carbon steel (dissolving Zn). HVO, HVOr, and methanol–HVOr–co-solvents were compatible with the metals. No fuels induced visible corrosion on the metals’ surfaces. If corrosion products were formed in the fuel samples, they did not affect fuel parameters. Full article

The continuous industrial development that occurs worldwide generates the need to develop new materials with increasingly higher functional properties. This need also applies to the basic material for electricity purposes, which is copper. In this article, we carry out studies on the influence of various alloying elements such as Mg, In, Si, Nb, Hf, Sb, Ni, Al, Fe, Zr, Cr, Zn, P, Ag, Sc, Pb, Sn, Co, Ti, Mn, Te and Bi on the electrical and mechanical properties of ETP-grade copper. The research involves producing copper alloys using the gravity die casting method with alloy additions of 0.1 wt.%, 0.3 wt.% and 0.5 wt.%. All resulting materials are cold-worked to produce wires, which are subsequently homogenized and annealed. The materials produced in this manner undergo testing to determine their specific electrical conductivity, tensile strength, yield strength, elongation and Vickers hardness (HV10 scale). Full article

The effect of 0.2%Cr addition on the structure, phase composition, and mechanical properties of the novel cast and wrought Al-2.5Zn-2.5Mg-2.5Cu-0.2Zr-Er(Y) alloys were investigated in detail. Chromium is distributed between primary crystals (5.7–6.8%) of the intermetallic phase and the aluminum solid solution (0.2%) (Al). The primary crystals contain for the main part Cr, Ti, Er(Y). The experimental phase composition is in good correlation with the thermodynamic computation data. The micron-sized solidification origin phases (Al₈Cu₄Er(or Y) and Mg₂Si) and supersaturated (Al) with nano-sized Al₃(Zr,Ti) and E (Al₁₈Mg₃Cr₂) precipitates are presented in the microstructure of the novel alloys after solution treatment. The nucleation of η (MgZn₂) (0.5%), S (Al₂CuMg) (0.4%), and T (Al,Zn,Mg,Cu) (8.8%) phase precipitates at 180 °C, providing the achievement of a maximum hardness of 135 HV in the Al2.5Zn2.5Mg2.5CuYCr alloy. The corrosion potential of the novel alloy is similar to the E_cor of the referenced alloy, but the corrosion current density (0.68–0.98 µA/sm²) is still significantly lower due to the formation of E (Al₁₈Mg₃Cr₂) precipitates and S phase precipitates of the aging origin, in addition to the T phase. The formation of E (Al₁₈Mg₃Cr₂) precipitates under the solution treatment provides a lower proportion of recrystallized grains (2.5–5% vs. 22.4–25.1%) and higher hardness (110 HV vs. 85–95 HV) in the Cr-rich alloys compared to the referenced alloys. Solution treated, hot and cold rolled, recrystallized, water quenched and aged at 210 °C alloys demonstrate an excellent microstructure stability and tensile properties: YS = 299–300 MPa, UTS = 406–414 MPa, and El. = 9–12.3%. Full article

Many studies have been carried out on the phosphating of steel and aluminum alloys used in automotive engineering, but characterization of the properties of the phosphate layers formed by the co-phosphating of these alloys in the presence of different base metals is still lacking. In this study, the crystal structure and properties of the phosphate conversion layers formed on the surface of the aluminum alloys important in vehicle manufacturing (cast and forged AlSi1MgMn, and AA6014 panel) and the CRS SAE 1008/1010 reference steel plate by co-deposition prior to painting were investigated. On a process line set up for the phosphating of typical iron and steel alloys, the phosphate coating was formed using nitrite and nitroguanidine accelerators under identical technological parameters. The microstructure of the formed phosphate layers was examined using scanning electron microscopy (SEM), its phase composition using X-ray diffraction (XRD), and its elemental composition using energy-dispersive X-ray analysis (EDX). The suggested main crystalline phase (Zn_2.3(Ni_0.1Mn_0.6)(PO₄)₂·4H₂O) in the surface phosphate layer of both aluminum alloys studied was similar to hopeite, whereas in the steel plate, a minor hopeite phase were identified in addition to the main crystalline phosphophyllite phase (~95%). It can be concluded that, during the combined phosphating treatments, the surfaces of different aluminum and steel alloys behaved similarly to the individual treatments and did not impede the coating reactions of the other metal. To obtain an adequate coating of aluminum and steel alloys, fluoride should always be present in the production line. Comparing the effects of accelerators, we found that the use of nitrite accelerator with the same amount of fluoride resulted in a higher coverage and better quality of the surface protective layer of the aluminum alloys. However, for the steel plate, there was no significant difference between the phosphate coatings prepared with the two different accelerators. Full article

Microscopic content segregation is among the important reasons for the anisotropy of mechanical properties in the cast-rolled sheets of the 7B05 aluminum alloy. It is of great significance to study the uniformity of aluminum alloys in terms of the microscopic composition and structure. In this study, a precise method for composition quantification based on micro-beam X-ray fluorescence spectroscopy is established by parameter optimization and a calibration coefficient. Furthermore, this method was applied for exploring and quantifying the relationship between recrystallization and deformation microstructures. The results show that the comprehensive measurement effects of all elements are the best when the X-ray tube voltage is 50 kV, the current is 150 μA, and the single-pixel scanning time is 100 ms. After verification, the sum of differences between the measured values and the standard values for all elements using the calibration coefficient is only 0.107%, which confirms the accuracy of the optimized quantitative method. Three types of segregation indexes in national standards were used to capture small differences, and finally ensure that the segregation degrees of elements are Ti > Fe > Cr > Cu > Mn > Zr > Zn > Al. The quantitative segregation results obtained by the spatial-mapping method show that the difference in the content of Al and Zn is approximately 0.2% between the recrystallization region and the deformation region, the difference in the content of Fe and Ti is 0.018% and 0.013%, the difference in the content of Cr, Cu and Zr is approximately 0.01%, and the difference in the content of Mn is not obvious, only 0.004%. Full article

Aluminum cannot provide continuous cathodic corrosion protection under ambient conditions due to the formation of an insulating oxide layer and therefore it should be alloyed. Binary aluminum alloys with Cr, Zn and Sn from AlCl₃/1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) containing CrCl₂, ZnCl₂ or SnCl₂ have been deposited and their morphology and composition were investigated using SEM/EDS. The corrosion behavior of alloys with 2–4 wt% Cr, Zn or Sn was investigated using potentiodynamic polarization in 3.5 wt% NaCl solution, neutral salt spray test (NSS) and environmental exposure (EE). Pure aluminum provides excellent corrosion protection of steel in a chloride-containing environment, but not under ambient conditions. AlCr alloys show poor corrosion protection while AlZn alloys provide excellent corrosion protection in the NSS test and superior cathodic protection in the EE test compared to aluminum. AlSn alloys are highly active at even low tin contents and dissolve rapidly in chloride-containing electrolytes. However, a slightly improved cathodic protection in the EE test compared to pure aluminum has been observed. The results prove the necessity of alloying aluminum to achieve effective cathodic corrosion protection under mild atmospheric conditions. Full article

Microstructure optimization of Al-Zn-Mg-Cu-Zr aluminum alloys, particularly through recrystallization inhibition, for improved strength and corrosion resistance properties has been an important consideration in alloy development for aerospace applications. Addition of rare earth elements, sometimes combined with Cr, has been found to be beneficial in this regard. In this study, the role of a single addition of 0.1 wt.% Cr on microstructure evolution of an Al-Zn-Mg-Cu-Zr (7449) alloy during processing was systematically investigated by optical light microscopy, scanning electron microscopy, electron backscatter diffraction and scanning transmission electron microscopy. Susceptibility to localized corrosion after aging to T4, T6 and T76 conditions was evaluated by potentiodynamic polarization (PDP) measurements and an intergranular corrosion (IGC) test. A decrease in recrystallized fraction with 0.1 wt.% Cr addition was observed, which is attributed to the formation of Cu- and Zn-containing E (Al₁₈Mg₃Cr₂) dispersoids and the larger as-cast grain size. Moreover, the depletion of alloying elements from solid solution due to the formation of the Cu- and Zn-containing E (Al₁₈Mg₃Cr₂) dispersoids and η Mg(Zn,Cu,Al)₂ phase at its interface affects grain-boundary precipitation. The observed decrease in localized corrosion susceptibility with minor Cr addition is correlated with the microstructure and equally discussed. Full article

The effects of natural ageing treatment prior to artificial ageing treatment on the microstructures and mechanical properties of AA7075 Al-5.7Zn-2.6Mg-1.5Cu-0.18Cr-0.08Mn-0.05Si-0.17Fe (wt.%) aluminum alloy have been investigated. The hardness of solution-treated samples (91.0 HV) profoundly increased to 146.8 HV after 7 days of natural ageing. The purpose of the present work was to examine the kinetic hardening evolution in subsequent artificial ageing treatments of samples naturally aged for 7 days and their counterparts without natural ageing. The former were labelled as NA-7d samples, and the latter, NA-0d samples. After artificial ageing at 120 °C for 2 h, the hardness of NA-0d samples increased rapidly to 148.2 HV, which was approximately the same as that of the specimens with natural ageing for 7 days, compensating for the prior state of lower hardness without natural ageing. After being treated at 120 °C for 16 h, the ultimate tensile strength (UTS) and yield strength (YS) of NA-7d reached the highest value, respectively, 601 MPa and 539 MPa, followed by a slight decrement of UTS when aged to 24 h. On the other hand, NA-0d specimens aged at 120 °C for 16 and 24 h showed nearly the same UTS (598 MPa); the former possessed YS of 538 MPa, and the latter, 545 MPa. The results presumably reveal that the peak ageing condition for NA-0d samples can be achieved under 24 h ageing at 120 °C. Under the same treatment at 120 °C for 24 h, the size of η’ phase in NA-7d sample (with a length of 4.96 nm) coarsened and grew larger than that in NA-0d sample (with a length of 3.46 nm). In addition, some η’ phase in the NA-7d sample was found to be transformed into the η₂ phase. The results indicated that the naturally aged specimens (NA-7d) reached the peak ageing condition earlier, but did not significantly enhance the UTS in AA7075 aluminum alloy, as compared to the samples without prior natural ageing (NA-0d). Full article

Enhanced in vitro corrosion resistance, cytocompatibility, in vitro antibacterial activities, in vivo antibacterial activities, in vivo corrosion resistance and in vivo stimulation of bone formation on plasma-modified biodegradable Mg and its alloys are reviewed, where the plasma modification includes plasma ion implantation (PII), plasma immersion ion implantation (PIII), or plasma immersion ion implantation and deposition (PIII&D) techniques. PII, PIII, and PIII&D are useful surface modification techniques, which can alter the surface properties of the biomaterials while preventing the bulk properties, which is much desirable factor especially for Mg based biomaterials. At first, this paper reviews the improved corrosion resistance by the formation of protective passive surface layer containing Zr-O, Zr-N, N, Si, Al-O, Zn-Al, Cr-O, Ti-O, Ti-N, Fe, Y, Sr, P, Pr, Ce, Nd, Hf, Ta, or C on Mg or its alloys using PII, PIII, or PIII&D techniques. Then, this paper reviews the improved biological properties such as cytocompatibility, in vitro antibacterial activities, and in vivo antibacterial activities on plasma-modified Mg or its alloys. Finally, this paper reviews the improved in vivo corrosion resistance and in vivo stimulation of bone formation on plasma modified Mg alloys. This review suggests that PII, PIII, and PIII&D techniques are effective techniques to improve the in vitro and in vivo corrosion resistance of Mg and its alloys for the development of degradable bio-implants. Full article