Addition Of Mn Research Articles

Performance of nickel-manganese and nickel-cobalt-manganese mixed oxide catalysts in ethanol total oxidation

The mixed oxide catalysts containing Ni, Co, and Mn components in various molar ratios were examined in the total oxidation of ethanol and the effect of their composition on physical chemical properties and catalytic performance was studied. The catalysts were obtained by calcination (4 h at 500 °C in air) of the coprecipitated precursors. The chemical analysis (AAS), powder XRD, Raman spectroscopy, TEM, N2 adsorption, H2-TPR, and XPS were used for the catalysts characterization. Formation of mixed oxides was indicated by powder XRD and Raman spectroscopy: NiCo2O4 spinel together with NiO were detected in the Ni-Co catalysts, MnIV-containing mixed oxides Ni6MnO8 (murdochite) and NiMnO3 (ilmenite) were identified in the Ni-Mn samples, and Ni-Co-Mn mixed oxides with spinel structure were found in the Ni-Co-Mn catalysts. Combination of transition metal components in the catalysts resulted in a synergistic effect; easier reduction in H2-TPR measurements and enhanced catalytic performance compared to single-component Ni, Co, and Mn oxides were observed. Addition of Mn to the Ni and Ni-Co oxides increased their catalytic activity in the ethanol oxidation, which was higher than that of the Ni-Co catalysts. The Ni-Mn catalyst with Ni:Mn molar ratio of 1:1 showed the highest activity (50 % conversion of ethanol was achieved at 91 °C) and good selectivity (acetaldehyde and carbon monoxide were detected as main byproducts of the ethanol oxidation). High activity of the Ni-Mn catalysts can be ascribed to the presence of MnIV-containing mixed oxides, namely NiMnO3. Activity of the Ni-Co-Mn catalysts, especially those with high (Co+Mn) contents, was comparable with that of the most active Ni-Mn catalyst with Ni:Mn molar ratio of 1:1. The high activity of Ni-Co-Mn catalysts can be explained by the formation of spinel-type mixed oxides with rather poor structure ordering and large surface area.

Improving Mechanical Properties of Mg-Al-RE Alloys with the Formed Dimples of Al10Mn2RE Particles and Activated Pyramidal Slip with Mn Additions.

The effects of Mn addition on the room temperature tensile strength and deformation mechanisms of as-cast Mg-8Al-1Nd-1.5Gd-xMn alloys (x = 0, 0.3, 0.5, 1.0 wt.%) are investigated in this paper. The results indicate that the addition of Mn contributes to the precipitation of Al-Mn-RE intermetallics and the refinement of α-Mg matrices, thereby improving the tensile strength of the 1.0 Mn alloy at 190 MPa. The fracture mechanism of Mn-containing alloys transforms from a cleavage fracture to a ductile fracture as the Mn content increases from 0.3 to 1.0 wt.%. The presence of intermetallic particles in the dimples confirms the hindrance effect of Al10Mn2 (Nd,Gd) on dislocation slips. The novel technology of in-grain misorientation axes (IGMAs) is used to identify activated slip modes and deformation twins. It can be concluded that the activated pyramidal <a> slip during tensile deformation significantly promotes the ductility of the 1.0 Mn alloy with an elongation rate of 9.8%. It is worth noting that reducing the coarse 101¯2 tensile twins and enhancing the proportion of 101¯1 compressive twins and 101¯1-101¯2 double twins contributes to maintaining the continuous plastic deformation of Mg alloy.

Кінематичні показники та дихальна активність деконсервованих сперміїв баранів за додавання наноцитрату Mn, Zn та Cu до середовища для кріоконсервування

The aim of the work was to find out the effect of adding nanocitrate of Mn, Zn and Cu to the medium for cryopreservation of ram sperm on kinematic indicators and respiratory activity of thawed sperm. The experiment was conducted on six clinically healthy breeder rams of the Texel breed aged 2–4 years. After receiving the ejaculates of the rams, they were evaluated for the volume, concentration and motility of the sperm and were divided into control and experimental groups. Control sperm samples were diluted with lactose-yolk-tris-citrate-glycerol medium (LYTCGM). Nanocitrates of trace elements were added to the medium in experimental samples of ram sperm in the following doses: Zn and Mn — 2.5, 5.0 and 7.5 μg/l, Cu — 1.25, 2.5 and 3.75 μg/l. Diluted sperm was packaged in straws, equilibrated for 2.5 hours and frozen. After thawing of sperm, motility, morphological damage of sperm, kinematic parameters of sperm motility (CASA), oxidation and reduction activity of sperm were determined. A dose-dependent effect of Mn, Zn, and Cu nanocitrates upon their addition to LYTCGM was established. The addition of Mn and Zn nanocitrate at a dose of 5.0 μg/l to LYTCGM significantly (P&lt;0.05–0.01) increases the activity of thawed ram sperm, while the addition of Cu nanocitrate in increasing doses significantly reduces the motility of sperm in thawed ram sperm. Addition of Mn and Zn nanocitrate in an optimal dose of 5.0 μg/l to LYTCGM significantly (P&lt;0.05–0.01) reduces the number of spermatozoa degenerated and with damaged acrosomes, and with the addition of Cu nanocitrate in increasing doses, morphological disorders of germ cell significantly increase cells The addition of Mn and Zn nanocitrate at a dose of 5.0 μg/l to LYTCGM significantly (P&lt;0.01–0.001) increases the kinematic parameters of thawed ram sperm, and the addition of Cu nanocitrate in increasing doses significantly reduces the indicators of germ cell motility. The addition of Mn and Zn nanocitrates to the medium for cryopreservation of ram sperm increases the oxidation and inhibits the reduction activity of thawed sperm. Addition of Cu nanocitrate to LYTCGM in increasing doses reduces the oxidation and increases the reduction activity of thawed ram sperm.

Ellipsometry, transmission, and photoluminescence characterization of Mn-doped ITO thin films deposited by DC magnetron sputtering

Manganese-doped indium tin oxide (ITO) thin films (0–12.8 at% Mn) were deposited by DC magnetron sputtering. The structural, electrical, and optical properties of the films were studied. Optical characterization was emphasized and included ellipsometry, transmission, and photoluminescence (PL) measurements. Features of the energy band structure of ITO and Mn-ITO were extracted from PL spectra and Tauc analyses of absorption data. We concluded that the fundamental bandgap of ITO is ∼2.8 eV. A separate deep valence band, ∼0.8 eV below the valence band maximum, was confirmed to be involved in higher energy optical absorption and emission transitions. Both of these observations were consistent with recent published theoretical studies and spectroscopic measurements (XPS, XES, etc). Mn addition was found to result in a decrease of the transition energies. Additionally, Burstein–Moss shifts were observed.

Effects of Cr, Mn, and Fe on the hydrogen solubility of Ni in high-pressure hydrogen environments and their electronic origins: An experimental and first-principles study

Effect of the addition of Cr, Mn, or Fe to Ni on the material's hydrogen solubility are investigated to establish guidelines for designing materials authorized to use in high-pressure hydrogen environments. The exposure to 100 MPa hydrogen gas at 160 °C reveals that the addition of 30 wt%Fe to Ni decreases the hydrogen solubility by 40%, while the addition of 20 wt%Cr to Ni increases it by 65%. Surprisingly, incorporating 20 wt%Mn causes a remarkable increase of 992%. By employing a combined approach of a random alloy model based on the special quasi-random structure and first-principles calculations, we are able to semi-quantitatively predict the effects of these alloying elements on hydrogen solubility. Moreover, the deconvolution of hydrogen bonding energy into its volumetric, mechanical, and chemical components clarifies that the significant impact of Mn is primarily attributed to a substantial expansion of the lattice constant.

Iron and manganese availability drives primary production and carbon export in the Weddell Sea

Next to iron (Fe), recent phytoplankton-enrichment experiments identified manganese (Mn) to (co-)limit Southern Ocean phytoplankton biomass and species composition. Since taxonomic diversity affects aggregation time and sinking rate, the efficiency of the biological carbon pump is directly affected by community structure. However, the impact of FeMn co-limitation on Antarctic primary production, community composition, and the subsequent export of carbon to depth requires more investigation. In situ samplings of 6 stations in the understudied southern Weddell Sea revealed that surface Fe and Mn concentrations, primary production, and carbon export rates were all low, suggesting a FeMn co-limited phytoplankton community. An Fe and Mn addition experiment examined how changes in the species composition drive the aggregation capability of a natural phytoplankton community. Primary production rates were highest when Fe and Mn were added together, due to an increased abundance of the colonial prymnesiophyte Phaeocystis antarctica. Although the community remained diatom dominated, the increase in Phaeocystis abundance led to highly carbon-enriched aggregates and a 4-fold increase in the carbon export potential compared to the control, whereas it only doubled in the Fe treatment. Based on the outcome of the FeMn-enrichment experiment, this region may suffer from FeMn co-limitation. As the Weddell Sea represents one of the most productive Antarctic marginal ice zones, our findings highlight that in response to greater Fe and Mn supply, changes in plankton community composition and primary production can have a disproportionally larger effect on the carbon export potential.

Effect of Mn content in Mn2−2yCoyCryOx catalyst on catalytic performance for SCR at low temperature

Mn2−2yCoyCryOx series catalysts were prepared by solid-state reaction means, and selective catalytic reduction with ammonia (NH3-SCR) over the catalysts at low-temperatures was studied. A series of characterization was carried out to reveal the NO selective promotion effect of Mn addition on Co1Cr1Ox catalyst. Mn1Co0.5Cr0.5Ox has the widest active window (the conversion of NOx is more than 90% at 150–275 °C). The water resistance and sulfur resistance of the Mn1Co0.5Cr0.5Ox were excellent. There are Co3+, Cr6+, Mn4+ and a large amount of adsorbed oxygen on the surface of Mn1Co0.5Cr0.5Ox catalyst, which improves the oxidation–reduction ability and surface acidity of the catalyst.

Investigation of the effects of Sr and Mn doping on corrosion tribocorrosion and cyclic voltammetry performances of TiO2 nanotubes

In this study, manganese (Mn) and strontium (Sr) were doped into TiO2 nanotubes (TNT), which are frequently used in energy storage equipment. The aim of this study is to compare the corrosion tribocorrosion and cyclic voltammetry performances of doped TNTs after examining their structural characteristics. XRD and SEM were used to characterize the nanotubes. After the anodization processes, the inclusion of Mn and Sr in the TNT structure was confirmed by XRD analysis. In SEM analysis, it was observed that with the addition of Mn and Sr into the solution, longer nanotubes were formed with increased electrical conductivity. Increasing the nanotube length and shrinking the nanotube's inner diameter provided increased corrosion resistance. Increased surface hardness resulted in increased tribocorrosion resistance. In cyclic voltammetry experiments, the capacitance increased approximately 5 times in Sr-doped TNT compared to undoped TNT, while it increased 10 times in Mn-doped TNT.

Seasonality of phytoplankton growth limitation by iron and manganese in subantarctic waters

Phytoplankton indirectly influence climate through their role in the ocean biological carbon pump. In the Southern Ocean, the subantarctic zone represents an important carbon sink, yet variables limiting phytoplankton growth are not fully constrained. Using three shipboard bioassay experiments on three separate voyages, we evaluated the seasonality of iron (Fe) and manganese (Mn) co-limitation of subantarctic phytoplankton growth south of Tasmania, Australia. We observed a strong seasonal variation in a phytoplankton Fe limitation signal, with a summer experiment showing the greatest response to Fe additions. An autumn experiment suggested that other factors co-limited phytoplankton growth, likely low silicic acid concentrations. The phytoplankton responses to Mn additions were subtle and readily masked by the responses to Fe. Using flow cytometry, we observed that Mn may influence the growth of some small phytoplankton taxa in late summer/autumn, when they represent an important part of the phytoplankton community. In addition, Mn induced changes in the bulk photophysiology signal of the spring community. These results suggest that the importance of Mn may vary seasonally, and that its control on phytoplankton growth may be associated with specific taxa.

Solutions for an efficient arsenite oxidation and removal from groundwater containing ferrous iron.

Manganese (Mn) oxides are extensively used to oxidize As(III) present in ground, drinking, and waste waters to the less toxic and more easily removable As(V). The common presence of multiple other cations in natural waters, and more especially of redox-sensitive ones such as Fe2+, may however significantly hamper As(III) oxidation and its subsequent removal. The present work investigates experimentally the influence of Mn(III) chelating agents on As(III) oxidation process in such environmentally relevant complex systems. Specifically, the influence of sodium pyrophosphate (PP), an efficient Mn(III) chelating agent, on As(III) oxidation by birnessite in the presence of Fe(II) was investigated using batch experiments at circum-neutral pH. In the absence of PP, competitive oxidation of Fe(II) and As(III) leads to Mn oxide surface passivation by Fe(III) and Mn(II/III) (oxyhydr)oxides, thus inhibiting As(III) oxidation. Addition of PP to the system highly enhances As(III) oxidation by birnessite even in the presence of Fe(II). PP presence prevents passivation of Mn oxide surfaces keeping As and Fe species in solution while lower valence Mn species are released to solution. In addition, reactive oxygen species (ROS), tentatively identified as hydroxyl radicals (•OH), are generated under aerobic conditions through oxygen activation by Fe(II)-PP complexes, enhancing As(III) oxidation further. The positive influence of Mn(III) chelating agents on As(III) oxidation most likely not only depend on their affinity for Mn(III) but also on their ability to promote formation of these active radical species. Finally, removal of As(V) through sorption to Fe (oxyhydr)oxides is efficient even in the presence of significant concentrations of PP, and addition of such Mn(III) chelating agents thus appears as an efficient way to enhance the oxidizing activity of birnessite in large-scale treatment for arsenic detoxification of groundwaters.

Effect of Mn addition on the tellurium embrittlement resistance of GH3535 alloy

The effect of Mn addition on the tellurium (Te) corrosion and Te embrittlement resistance have been systematically investigated by comparing the standard GH3535 alloy and high-Mn one. After corroded in Te vapor at 700 °C, the more MnTe and (Cr, Mn)3O4 particles are formed on the surface in the high-Mn alloy than that in standard one. The high-Mn alloy possesses more MnTe particles at the grain boundaries near the surface. In the standard alloy, the Te mainly exist in the form of segregation at grain boundaries, and the distribution depth is more than that of MnTe in high-Mn alloy. The tensile tests indicated that the high-Mn alloy exhibits the higher ultimate tensile strength and elongation than the standard one in the corroded state. The deeper intergranular cracks can be observed from the gauge of tensile speicmens of standard alloy. These facts proved that the high-Mn alloy is more resistant to Te embrittlement. By connecting the corrosion and embrittlement behaviors, it can be concluded that Te embrittlement can be significantly improved by transforming the Te segregation into the intergranular MnTe tellurides. Our study provides one new protection strategy for the tellurium embrittlement of alloys, which seems to be more applicable to the harsh service environment.

The Possible Solutions for the Cell of Post-Lithium Era, New Ideas for Sodium-Ion Batteries

Fossil fuels are the most used energy source in the world, which risks in environmental pollution, resource depletion or geopolitical conflicts. These all have led to the emergence of intermittent renewable and cleaner energy sources such as wind, solar and wave, for which there is a strong demand for huge energy storages. One of the most known technology is Li-ion, however the alternatives must be researched to meet the increasing needs. One of the ideas is sodium-ion technology, which is one of the most popular post-lithium cell technology.Sodium, in contrast to lithium, has almost unlimited resources everywhere including the vast reserves in the oceans. In addition, sodium is the one of the most abundant element in the Earth’s crust. The price of sodium is low compared to lithium. Furthermore, thanks to the similar physical properties of those two elements, NIBs share similar electrochemistry and fabrication techniques to LIBs. However, there are some obvious differences between NIBs and LIBs systems. The size difference affects transport properties, phase stability, and interphase formation (Hwang et al., 2017). Because of those dissimilarities, many battery components cannot be directly transplanted from a LIB to a NIB. Moreover, since Na-based batteries are an emerging technology, there is a relative lack of new materials that would enable the electrochemistry of Na and the discovery of new redox couples (Slater et al., 2013). For instance, a significant hurdle for sodium electrochemical systems is the lack of high-performance electrodes and electrolyte materials that are easy to synthesize, safe, non-toxic, durable, and inexpensive (Slater et al., 2013).That is why, there are many challenges due to the Na-ion technology, especially introducing novel cathodic materials. To answer this problem, several new types of electrodes, containing Ti, Y, Ni and Mn additives will be introduced in this presentation The compatibility of cathodes with electrolyte is the next topic, which will be presented. As the example, modern electrolytes, containing the low coordinating Hückel type salt (4,5-dicyano-2-(trifluoromethyl)imidazolate, NaTDI) as a main electrolyte component and different additives and solvent mixtures will be shown. The new formulations with the best conductivity performance, physicochemical stability, and interfacial contact with electrodes were examined and verified. Using the SEM, Raman, EDS, and XRPD analysis, the full characterization of the active materials and electrodes was performed to introduce the new possible electrode-electrolyte compositions. All of these led to presenting the new possible compositions of electrodes and electrolytes, which gives new perspectives for Na-ion battery technologies.ReferencesSlater, M. D., Kim, D., Lee, E., & Johnson, C. S. (2013). Sodium-Ion Batteries. Advanced Functional Materials, 23(8), 947–958. https://doi.org/10.1002/ADFM.201200691Hwang, J. Y., Myung, S. T., & Sun, Y. K. (2017). Sodium-ion batteries: present and future. Chemical Society Reviews, 46(12), 3529–3614. https://doi.org/10.1039/C6CS00776GAcknowledgementsStudies were funded by ENERGYTECH-1 project granted by Warsaw University of Technology under the program Excellence Initiative: Research University (ID-UB).

Effect of Mn Addition on Microstructure, Mechanical Properties and Die Soldering of Rheocasting Al-7Si-0.3Mg Alloys

The effect of Mn additions (up to 0.8 wt.%) into Al-7Si-0.3Mg alloy on the microstructure, mechanical properties and die soldering was firstly investigated in gravity die casting conditions, with the aim to obtain an optimized Mn addition level. Especially, the stirring testing on H13 die material was used to elucidate the effect of Mn additions on the Fe concentration in the Al melting as a function of melting temperature (690 °C) and holding time (up to 32 h), which can provide an indirect sign of die soldering. On this basis, the addition of 0.6wt.%Mn into Al-7Si-0.3Mg alloy was found to be beneficial for microstructure, strength and die soldering. Secondly, rheocasting of Al-7Si-0.3Mg alloy without (Mn-free alloy) and with 0.6 wt.% Mn (Mn-containing alloy) was performed. The addition of 0.6wt.%Mn into Al-7Si-0.3Mg alloy was found to have following effects: (i) solidification temperature of α-Al is increased and a higher (about 20 °C) rheocasting temperature is therefore needed, but no significant die soldering problem was observed even with increasing casting temperature, (ii) Mn-containing phase forms along grain boundaries and within Al matrix, which increases tensile and yield strength but decreases elongation in as-cast, T5 and T6 conditions, (iii) number density and volume fraction of pores increases, and (iv) die soldering slightly improves. This paper demonstrates that the addition of 0.6wt.%Mn into Al-7Si-0.3Mg alloy is beneficial for microstructure, strength and die soldering in both gravity die casting and rheocasting conditions.

BaSn0.96-XZr0.04MXO3 (M = Mn, Fe or Co, x = 0, 0.02) for spin-based devices: Ferromagnetic properties

In this study, Zr and/or Mn, Fe or Co ions were used to induce a robust room temperature ferromagnetic nature in perovskite BaSnO3 for high performance information applications. Dilute magnetic semiconductor compositions with formula of BaSn0.96-XZr0.04MXO3 (M = Mn, Fe, Co, x = 0, 0.02) have been synthesized at 1150 °C. For all compositions, mono-phase of cubic BaSnO3 structure with very small impurities of SnO2 were recorded based on X-ray diffraction analysis. The relation between ionic size of dopants and crystal dimension of BaSnO3 suggests the of Sn4+-site by Zr4+, Mn2+, Fe2+ or Co2+ ions. Extended absorption tails to visible light region were found for BaSn0.94Zr0.04Mn0.02O3 and BaSn0.94Zr0.04Co0.02O3 samples, owing to strong defect band transition absorption. Due to the addition of Zr and/or Mn, Fe or Co ions high refine of BaSnO3 morphology from inhomogeneous large grains to well distribute small one were seen. The XPS results of BaSn0.96Zr0.04O3 and BaSn0.94Zr0.04Co0.02O3 samples confirm that Ba, Sn, O and Zr are in the oxidation states of +II, +IV, −II and +IV/+III, respectively. Magnetically, incorporation of 4 wt% Zr4+ ions (empty 4d-orbital) induced a full-saturated spin ferromagnetic order with saturation magnetization of 1.16 emu/g, retentivity of 0.11 emu/g and coercivity of 147 Oe. Also, codoping by Zr/Co ions stimulates a full-saturated spin ferromagnetic order with saturation magnetization of 1.36 emu/g, retentivity of 0.17 emu/g and coercivity of 149 Oe. The empty 4d-Zr4+ ions have high ability in reversing the diamagnetic nature of BaSnO3 to ferromagnetic one through interaction with oxygen vacancies. The outer 4d-shell of Zr and 3d-orbital of Co with the oxygen vacancies induce the strong magnetic exchange interaction. Through looking into the previous studies on the magnetic properties of BaSnO3, the recorded saturation magnetization of 4 wt% Zr and 4 wt% Zr + 2 wt% Co ions are remarkable values.

Evolutionary mechanism of the precipitation behavior and organization of iron-containing intermetallic phase during solidification of recycled high-Fe Al-Zn-Mg-Cu melts

The remelting of aluminum scraps can result in the accumulation of impurities, with iron being the most prevalent among them. The presence of such impurities can cause downgrading and hindered utilization of the material. Despite this, the evolution mechanism of the Iron-containing Intermetallic Phase (IIP) in recycled high-Fe and low-Si aluminum melt has received limited attention and requires further investigation. This study investigates the evolution mechanism underlying the precipitation behavior and organization of the IIP during the solidification process of recycled high-Fe Al-Zn-Mg-Cu melts, utilizing a combination of simulation and experiment. Our findings indicate that the precipitation behavior of the high-temperature precipitation phase (HPP) in the melt is influenced by the Mn and Si, which subsequently determines the organization of the IIP. Specifically, the predominant forms of IIP in the recycled high-Fe Al-Zn-Mg-Cu alloys are lamellar and hollow rod-like phases with anisotropic, as well as skeletal phases with isotropic organization. Moreover, the synergistic addition of Mn and Si can increase the precipitation temperature (PT) and precipitation temperature interval (PTI) of the Al15(Fe,Mn)4Si2 phase in the melt, leading to the transformation of the IIP into a skeletal organization that can be easily removed and has less impact on the material properties. These findings provide insights into alloy design strategies aimed at minimizing the impact of iron accumulation on the cycle life of aluminum scraps and the performance of recycled aluminum.

Determination of Interaction Parameters between Mn and Al and the Influence of Mn on Al2O3 Inclusions Formation in High Mn and Al Content Fe-Mn-Al-O Melts at 1873 K

For the purpose of determining the interaction parameters between Mn and Al, and the influence of Mn on Al2O3 inclusions formation in the Fe-Mn-Al-O melts with high Mn and Al contents, three groups of Fe-Mn-Al-O melts with the initial Al content of 3, 5, and 7 mass% and different Mn contents were equilibrated with pure solid Al2O3 in an Al2O3 crucible at 1873 K and Ar-H2 atmosphere. Then, the interaction parameters between Mn and Al were deduced using the WIPF (Wagner’s Interaction Parameter Formalism) and the R-K polynomial (Redlich-Kister type polynomial), respectively. From the WIPF, the first- and second-order interaction parameters, eAlMn and rAlMn, were determined to be 0.0292 and −0.00016, respectively. From the R-K polynomial, the binary interaction parameters, ΩMn-Al0 and ΩMn-Al1, were determined to be 73,439 J/mol and −34,919 J/mol, respectively. The applicability of the WIPF to high Mn and Al content Fe-Mn-Al-O melts was investigated by comparing the Al activity calculated by the WIPF and the R-K polynomial using the obtained data. The results showed that WIPF can be used in high Mn and Al content melts in the current concentration range. Further from the iso-activity contours of Al, the activity of Al increases with increasing Al or Mn content. Finally, the thermodynamic calculations show that the addition of Mn decreases the equilibrium O content at the same Al content, making the formation of Al2O3 inclusions easier.

Influence of Sr and Mn Elements on the Microstructural Characteristics, Mechanical, and Anticorrosion Properties of Zn‐Based Biodegradable Materials

This study specifically focuses on investigating the effects of Mn and Sr additions on the microstructure, mechanical properties, and anticorrosion behavior of as‐extruded Zn–Mn–Sr alloys, with the ultimate goal of developing biodegradable implants. The microstructural observations reveal that the incorporation of Mn and Sr elements plays a crucial role in refining the hcp (Zn) grains within the alloys. Moreover, the intermetallic phase SrZn13 is observed to precipitate along with the eutectic microstructure. Mechanical testing demonstrates that the addition of Sr shows the potential to enhance the mechanical properties of Zn–Mn alloys, and also results in a trade‐off with ductility. Notable alloys, BZA920, exhibit the highest values of yield strength at 219.8 ± 5.2 MPa and ultimate tensile strength at 240.6 ± 4.3 MPa; alloys of BZA315, BZA615, and BZA915 exhibit excellent ductility of over 40%. The electrochemical and immersion tests conducted in simulated body fluid (SBF) solution demonstrate the alloys’ favorable corrosion resistance. The corrosion rates range from 0.05 to 0.15 mm year−1, indicating their potential suitability as implant materials. Overall, this study highlights the exceptional mechanical properties, favorable corrosion resistance, and excellent biocompatibility of the investigated Zn–Mn–Sr alloys.

Effects of Alloying Elements on the Dissolution and Precipitation Behaviour of Fe in Mg-Al Alloy Melts

It is necessary to strictly control the iron (Fe) impurity in Mg-Al alloys to guarantee good corrosion resistance and mechanical properties. In this work, the effects of alloying elements and temperatures on the solubilities of Fe in the Mg-Al-based alloy melts (Mg-rich liquid phases) at 963–1033 K were studied by combining the in situ sampling method for the high precision solution values and the multiple regression numerical analysis method for the feature analysis. The solubilities of Fe in Mg-xAl (x = 1 and 3 wt.%) alloy melts could be significantly reduced by adding the yttrium (Y) or manganese (Mn) elements. However, the solubilities of Fe in Mg alloy melts were not in a monotonous relationship with the contents of the alloying elements in the Mg alloys. For the addition of Mn or Y, the lowest solubilities of Fe presented in the Mg-rich liquid phases were for the Mg-xAl alloys with the addition of 2 wt.% Mn or 1 wt.% Y, respectively. Additionally, the Fe-containing precipitations in the related systems were analysed and the Fe was mainly combined with Mn or Y and precipitated, which contributed to the removal of Fe from the Mg melt. The present study provides fundamental thermodynamic information regarding Mg-Al-Fe based systems and the design principle for the removal of Fe in Mg alloys.

Enhancing the Strength and Toughness of A356.2-0.15Fe Aluminum Alloy by Trace Mn and Mg Co-Addition

In the present work, microalloying is put forward to improve the microstructure and tensile properties of A356.2-0.15Fe (wt.%) alloy by the co-addition of trace Mn and Mg. A suitable Mn/Fe mass ratio of 0.5 is obtained for alloys with 0.15Fe. The yield strength, ultimate tensile strength, and elongation of the A356.2-0.15Fe alloy with an Mn/Fe ratio of 0.5 and containing 0.42 wt.% Mg is 179 MPa, 286 MPa, and 9.1%, respectively, which is acceptable for automotive wheel hub applications. Optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electron-probe microanalyzer (EPMA) methods are used to characterize the microstructure of the alloys. The results indicate that Mn addition promotes the transformation of the acicular β-Al5FeSi phase to the block-shaped α-Al(Fe, Mn)Si phase. The ratio of length/width of the Fe-rich phase in the alloy is reduced by 78.8% with an Mn/Fe ratio of 0.5 and containing 0.35 wt.% Mg, compared with that of the alloy without Mn addition and containing 0.35 wt.% Mg. The addition of Mg reduces the secondary dendrite arm spacing (SDAS) from 26.1 μm to 20.9 μm. The volume fraction of the precipitated Mg2Si phase in the alloy containing 0.42 wt.% Mg increases by 60% compared with that in the alloy containing 0.35 wt.% Mg. The morphology transformation of the Fe-rich phase, the reduction of SDAS, and the increase in volume fraction of precipitated Mg2Si phase comprehensively contribute to the improvement of A356.2-0.15Fe alloy. The microstructure evolution mechanism and the effect of microstructure on tensile properties are analyzed and discussed.

Biodegradable Zn−1wt.%Mg(−0.5wt.%Mn) Alloys: Influence of Solidification Microstructure on Their Corrosion Behavior

The development of biodegradable Zn-based alloys for implants that effectively mimic the functionality of native bone throughout the healing process is a multifaceted challenge; this is particularly evident in the task of achieving appropriate corrosion rates. This work explores the incorporation of 0.5wt.%Mn into a Zn−1wt.%Mg alloy, with focus on the relationship between corrosion behavior and microstructure. Electrochemical corrosion tests were carried out in a 0.06 M NaCl solution using as-solidified samples with two distinct microstructural length scales. Mn addition was found to induce significant electrochemical active behavior. Localized corrosion was predominant in interdendritic regions, with the ternary alloy exhibiting a higher susceptibility. For both alloys, the coarsening of the microstructure promoted a slight inclination to accelerate the corrosion rates in both biodegradable Zn alloys. The corrosion rate showed an increase of about nine-times with Mn addition for coarser eutectic spacings, while for finer ones, the increase was by about 22 times.