Effect Of Mn Content Research Articles

Effect of Mn content on the microstructure, mechanical properties and corrosion behavior of Ti–Nb–Zr–Mn alloys processed via spark plasma sintering

Herein, β-type Ti–Nb–Zr–Mn alloys were prepared by ball milling and spark plasma sintering. The effects of Mn addition and quenching treatment on the microstructure, mechanical properties, and corrosion behavior of the alloy were investigated. The Ti–Nb–Zr–Mn alloys are predominantly constituted of equiaxed β Ti grains with a small proportion of ω phase. An increase in Mn content inhibits the precipitation of the ω phase while promoting a more homogeneous solid solution. The tensile strength of the as-prepared alloys decreases and then increases, whereas the plasticity demonstrates the opposite trend. The Elastic modulus and hardness roughly show a trend of decreasing and then increasing. Additionally, the Ti–24Nb–4Zr–2Mn alloy, after undergoing a solid solution treatment at a temperature of 950 °C and subsequent water quenching (referred to as M2-950), demonstrates exceptional comprehensive performance, showing a yield strength of 956 ± 4 MPa, an ultimate strength of 995 ± 13 MPa, an elongation of 16.4 ± 1.6 %, a hardness of 312 ± 11 H V, and an Elastic modulus of 72.6 GPa. Moreover, the corrosion behavior in Ringer's solution was extensively investigated, and the M2-950 alloy has superior corrosion resistance.

Effective Photogeneration of Singlet Oxygen and High Photocatalytic and Antibacterial Activities of Porous Mn-Doped ZnO-ZrO<sub>2</sub> Nanocomposites

Disperse porous Mn-doped ZnO-ZrO<sub>2</sub> nanocomposites were prepared using the facile polymer-salt method. The effect of Mn content on the crystal structure, composite morphologies, their ability to photogenate the singlet oxygen, luminescence properties, and bactericidal activities were studied. The crystal structure and morphology of these materials were investigated using XRD and SEM analysis. It was found that obtained nanocomposites consist of small (~9 nm) hexagonal ZnO and fine ZrO<sub>2</sub> crystals and the embedding of Mn ions expands the crystal cells of ZnO crystals. Photoluminescence spectra indicate the presence of different structural defects (interstitial Zn ions and oxygen vacancies in ZnO and oxygen vacancies in ZrO<sub>2</sub> crystals). Mn-doped ZnO-ZrO<sub>2</sub> nanocomposites can photogenerate singlet oxygen under visible (λ = 405 nm) irradiation. The increased power density of the exciting blue (λ = 405 nm) light significantly enhances the singlet oxygen photogeneration by prepared composites. The dependence of the intensity of singlet oxygen photogeneration by composites on the power density of exciting radiation (at its variation in the range 0.8 ÷ 1.6 W/cm<sup>2</sup>) is close to linear. Mn-doped ZnO-ZrO<sub>2</sub> composites demonstrate superior antibacterial activity against the gram-positive bacteria <em>Staphylococcus aureus ATCC 209P</em>. It was found that highly dispersed porous Mn-doped ZnO-ZrO<sub>2</sub> nanocomposites are promising for practical environmental and medical applications.

Effect of Mn content in the Ti/Zr-based AB2 Laves type alloys on their electrochemical performance

In this work, we studied the impact of Manganese content on the structural and electrochemical properties of the AB2 Laves phase alloys. These multicomponent alloys were composed of 7 individual constituents with a composition Ti0.15Zr0.85La0.03V0.12Mn0.7+xFe0.12Ni1.2 and a variable Manganese content, x = 0.021, 0.035, 0.070. The alloys were prepared using arc melting and rapid solidification techniques. These alloys were characterized by X-ray diffraction and Scanning Electron Microscopy with X-ray Energy Dispersive Spectroscopy allowing to probe the phase-structural composition of the alloys, their microstructures, and elemental distribution among the phase constituents. The rapidly solidified alloys exhibited refined microstructures with a more uniform elemental distribution compared to their as-cast counterparts, the latter containing larger grain sizes and clustered La-rich phases. C15 and C14 Laves type structures contributed to the phase-structural composition of the alloys, with their proportions influenced by the Manganese content and the chosen preparation method. The study revealed a multi-feature relationship between the Manganese content, the phase abundances, and the electrochemical performances, with notable disparities between as-cast and rapidly solidified alloys. The alloy containing 3 wt% Manganese demonstrated the highest discharge capacity and superior activation performance for both preparation methods, suggesting the best choice when optimizing the composition of the anodes for achieving the best battery performance. The highest hydrogen diffusion rate was observed for the alloy containing 10 wt% Manganese which can be related to the catalytic role of Manganese in the processes of hydrogen exchange when present in these alloys.

Effect of Mn Content on the Microstructure, Mechanical, and Corrosion Properties of Porous Mg–1Zn–1Ca Scaffolds

Porous Mg alloys scaffolds are considered as an attractive strategy for bone repair due to their good biodegradability, biocompatibility, and suitable mechanical properties. In this study, porous Mg–1Zn–1Ca–xMn (x = 0, 0.2, 0.5, 0.8) scaffolds with cubic pore structure are prepared, and the size of main pore and interconnected pores of the scaffolds are predicted to be 355–450 and 30–50 μm, respectively. Among the four scaffolds, Mg–1Zn–1Ca–0.8Mn scaffold possesses good mechanical properties, with a maximum yield strength of 27.1 and an elastic modulus of 0.66 GPa. However, Mg–1Zn–1Ca–0.5Mn scaffold exhibits the optimal corrosion resistance with a corrosion rate 1.02 mm year−1 after 5 days immersion in Hank's solution. This is mainly attributed to α‐Mn phase, which is uniformly distributed on the substrate and uniformly degraded.

Effect of Mn addition on microstructure and corrosion behavior of AlCoCrFeNi high-entropy alloy

In this study, the effects of Mn content on the microstructure and corrosion resistance of AlCoCrFeNiMnx (x = 0, 0.25, 0.5, 0.75, and 1) high-entropy alloys were investigated. The results indicate that with increasing Mn content, the HEAs consistently comprise nanophase BCC geometry with different shapes embedded in the ordered B2-phase matrix, and the morphology of the microstructure changes from a coarse dendritic structure to a fine dendritic structure, then to a completely columnar dendrite structure. The microhardness of the HEAs increases gradually to 620 HV0.2 when x = 1, owing to the solid-solution and fine-grain strengthening. The corrosion resistance of the HEAs in 3.5 wt% NaCl solution first increases and then decreases, reaching a maximum with the lowest self-corrosion current density of 2.869 × 10−8 A∙cm−2 when x = 0.5. Improvement in corrosion resistance is related to a reduction in degree of composition segregation in the microstructure of HEAs, which leads to the formation of a dense and complete passivation film on the surface of the alloys. However, when the Mn content is in the range of 0–0.5, the pitting potential of the HEAs gradually decreases, although the passivation current density also gradually decreases. Higher Mn content (x > 0.5) leads to a transition of the HEAs from passivation to active dissolution. This indicates that the stability of the passivation film on the HEAs decreases with higher Mn content. XPS analysis revealed a gradual decline in the relative content of Cr2O3 and a gradual increase in the presence of unstable oxides such as MnO and Mn2O3 in the passivation film, leading to this phenomenon. The present work reveals that the addition of Mn in the AlCoCrFeNi HEA affects not only the microstructure and composition segregation but also the composition and stability of the passivation film, leading to a non-monotonic variation in the corrosion performance of the present HEAs with respect to the Mn content.

Effects of Mn on the interface bonding and mechanical properties of TiC reinforced steel matrix composites

The addition of alloying elements to the steel matrix during the preparation process can significantly affect the properties of TiC reinforced steel matrix composites. In this study, the effects of Mn on the electronic structure and crystal structure stability of Fe supercells, along with as well as the stability of the TiC/Fe(Mn) interface, were analyzed through first-principles calculations. Additionally, 8 vol% TiC/Fe–C composites were prepared through the master alloy method. The effects of Mn contents (0, 0.8, 1.2, 1.6, and 2.0 wt%) on the interface mismatch and mechanical properties of the composites were investigated. The results revealed that Mn formed a solid solution and generated a stronger Fe–Mn bond compared with the Fe–Fe bond, and no interface chemical reaction occurred. The addition of a small amount of Mn improved the interface bonding between TiC particles and the steel matrix. The TiC particles were uniformly distributed in the matrix at the grain boundaries, with only a small amount dispersed within the grains. The TiC particles and steel matrix exhibited excellent, continuous, and stable interface bonding. The addition of Mn reduced the interface mismatch between TiC particles and the matrix. As the Mn content increased, the tensile strength and elongation of the composites first increased and then decreased, while the hardness of the composites increased. The addition of 1.2 wt% Mn resulted in an increase in the tensile strength, elongation, and hardness of the composite by 1160 MPa, 7.3%, and 43 HRC, respectively. These values were 109.8%, 151.7%, and 31.1% higher than those of the composite without Mn addition. However, an excess of Mn led to severe distortion of the Fe lattice and clustering at the interface, resulting in the degradation of the mechanical properties in the composites.

Effect of Mn content on microstructure and properties of AlCrCuFeMnx high-entropy alloy

Effect of Mn content on microstructure and properties of AlCrCuFeMnx high-entropy alloy

Mechanism of the synergistic effect of solid solution strengthening and fine grain strengthening in an as-cast Cu–9Ni–6Sn alloy induced by Mn

The effects of Mn content on the Sn distributions, grain sizes, second phases, and mechanical properties of Cu–9Ni–6Sn-XMn alloys (wt.%, X = 0, 0.1, 0.5, and 1.0) were studied in this paper. The mechanisms of acting and strengthening through which Mn could promote grain refinement in the alloy were discussed. The results showed that the addition of Mn transforms the as-cast microstructure of the alloy into equiaxed grains, and the grains are obviously refined. When the amount of Mn is approximately 0.1 wt%, the average grain size of this alloy is 91.75 μm, and the grain refinement effect is greatest in the experimental range. In addition, Mn increases the uniformity of the distribution of Sn in the as-cast microstructure. Differential scanning calorimetry (DSC) analysis revealed that the addition of Mn increases the undercooling of the as-cast Cu–9Ni–6Sn alloy and decreases in the critical nucleation radii of the grains. Further microstructure observation showed that Mn is dissolved mainly in the γ-(Cu,Ni)3Sn phase. Consequently, the interfacial relationship between the γ-(Cu,Ni)3Sn phase and the matrix transforms from incoherent to semicoherent. Compared with those of the Cu–9Ni–6Sn alloy, the strength and elongation of the alloy with added Mn are relatively great. When the content of Mn is 0.1 wt%, the strength of the alloy increases from 359.75 MPa to 423.54 MPa, while the elongation remains at 19.14 %. The synergistic effect of solution strengthening and fine grain strengthening of Mn is the main reason for the great improvement in the mechanical properties of the alloy.

Effect of Mn content on mechanical properties and corrosion resistance of Ti–8Mo-xMn alloys through the vacuum sintering process

This study mixed various powders (Ti, Mo, and Mn) according to the nominal Ti–8Mo-xMn (x = 1, 3, 5 wt%) composition, and vacuum sintered the compacts of the Ti–Mo–Mn alloys at 1220 °C, 1240 °C, 1260 °C, and 1280 °C for 1 h. The experimental results show that the Ti–8Mo–3Mn alloys sintered at 1260 °C had better comprehensive properties, with a relative density of 96.71 ± 0.14 %, transverse rupture strength (TRS) of 1624.4 ± 29.2 MPa, and hardness of 67.8 ± 0.4 HRA. However, due to the microstructure evolution and increased amount of Mn in the Ti–8Mo-xMn alloys, the TRS shows a significant increase. Consequently, the suitable Mn content of the Ti–8Mo–3Mn alloys, which proves advantageous to the TRS, results from the uniformly distributed lamellar-like Widmanstätten microstructure and the basket-net microstructure. Moreover, the Ti–8Mo-xMn alloy does not have intermetallic compounds, and only consists of two phases, α-Ti and β-Ti. Furthermore, the sintered Ti–8Mo–3Mn alloys possess the suitable corrosion current (Icorr was 4.56 × 10−5 A cm−2) and polarization resistance (Rcorr was 569.76 Ω cm2) in 0.1 N H2SO4 solutions, which confirms that sintered Ti–8Mo–3Mn alloys can improve mechanical properties.

Effect of Mn content on crystallization behaviors and magnetic properties of FeCoNiBMn high-entropy amorphous alloys

FeCoNi-based high-entropy alloys (HEAAs) attracted much attention because of their good thermodynamic stability, mechanical properties and soft magnetic properties. In this paper, Fe22Co22Ni22B34-xMnx (x = 6–22 at%) HEAAs were designed and the effects of Mn on the crystallization behaviors, magnetic performance, and mechanical property were investigated. The crystallization behaviors of the FeCoNiBMn HEAAs are: 1) 12–16 at% Mn: am → am’ + M23B6 → M23B6 + fcc; 2) 18 at% Mn: am → am’ + bcc + M23B6 → bcc + M23B6 → fcc + M23B6; and 3) 20–22 at% Mn: am → am’ + bcc → bcc + M23B6 → fcc + M23B6. Two parameters ΩA and VEC are proposed to predict the primary precipitates of FeCoNi-based HEAAs. All as-spun ribbons exhibit excellent soft magnetic properties with a very low coercivity (Hc) of less than 1.5 A/m and a maximum saturation magnetization (Bs) of 0.82 T. The 14 at% Mn alloy exhibits very low Hc of less than 4 A/m even after complete crystallization. Magnetic properties and Vickers hardness of crystalline ribbons are closely related to crystallization behaviors.

Coupled Precipitation of Dual-Nanoprecipitates to Optimize Microstructural and Mechanical Properties of Cast Al–Cu–Mg–Mn Alloys via Modulating the Mn Contents

The effect of Mn content on the microstructure evolution and mechanical properties of Al–Cu–Mg–x Mn alloys at ambient temperature was investigated. The findings show that in the Mn-containing alloys at the as-cast state, the blocky primary T(Al20Cu2Mn3) phase coexisting with the Al2Cu phase appeared. With the increase in Mn content, the majority of the Al2Cu phase dissolved, nd a minor amount of the T phase remained at the grain boundary after solution treatment. The rod-like TMn (Al20Cu2Mn3) nanoprecipitate was simultaneously distributed at grain boundaries and the interiors, while a high density of needle-like θ″ (Al3Cu) nanoprecipitate was also observed in the T6 state. Further increases in Mn content promoted the dispersion of the TMn phase and inhibited the growth and transformation of the θ″ phase. Tensile test results show that 0.7 wt.% Mn alloy had excellent mechanical properties at ambient temperature with ultimate tensile strength, yield strength, and fracture elongation of 498.7 MPa, 346.2 MPa, and 19.2%, respectively. The subsequent calculation of strengthening mechanisms elucidates that precipitation strengthening is the main reason for the increase in yield strength of Mn-containing alloys.

The effect of Mn content on a novel Al–Mg–Si-Sc-Zr alloy produced by laser powder bed fusion: The microstructure and mechanical behavior

Scandium is very expensive and limits the application potential of Sc containing alloys. A novel high-strength Al–Mg–Mn-Sc-Zr alloy was designed for reducing Sc. Multiple strengthening mechanisms were utilized for designing this alloy, especially for the solid solution strengthening which benefits from ultrahigh cooling. With the addition of Mn and Si, the strength of our alloy reaches comparable level of similar alloys while the Sc content is 40–60 % less than them. The effect of Mn addition on microstructure and mechanical properties were carefully studied. Near full-dense samples with relative density >99.88 % were obtained with the help of overlapping prediction model. The continuous Mg2Si network was observed with Si introduction and broken up with increasing Mn content. According to the tensile experiment results and corresponding calculations, it was considered that the thermal stability and the effect of precipitate strengthening was slightly deteriorated. However, obvious improvement of the tensile strength was observed with increasing Mn addition, and the ductility maintains in a certain range. After aging at 280 °C for 4 h, the sample of 1.4 wt% Mn exhibits the highest ultimate strength of 497.08 ± 7.22 MPa, and possesses a considerable ductility of 8.01 ± 0.34 %. The Portevin-Le Chatelier (PLC) effect was observed in stress-strain curves, which reflects a dynamic strain aging of mobile dislocations and solute atoms. After aging, the stress amplitude and waiting time of serration flow decrease obviously, because of the introduction of bypassing precipitates and reduction of diffusion time. Compared with other similar alloys, our alloy exhibited comparable yield strength and elongation, but considerable advantages in material costs resulting from lower Sc content. It will offer not only an idea for alloy design utilizing the ultra-high solid solubility of elements, but also a feasible way to further expand application field of high-strength Al-based alloys through reducing the material costs.

Effect of Mn Content on Microstructure and Mechanical Properties of Fe–Mn–Cr–C High‐Manganese Steels Produced Using Laser‐Directed Energy Deposition

The microstructure and mechanical properties of high‐manganese steel (HMnS) fabricated using laser‐directed energy deposition (LDED) with Fe–Mn–4Cr–0.4C alloys with Mn contents of 13, 18.5, and 24 wt% are investigated. Additionally, the effect of annealing heat treatment on the microstructure and mechanical properties of the deposited HMnS is examined. Regardless of the manganese content, the deposited HMnS exhibits a fine microstructure without any defects (cracks or voids) and a strong fibrous texture along the <001>//building direction of the primary austenite phase. In addition, regardless of the manganese content, the grain size increases during annealing heat treatment, and the hardness decreases as the annealing temperature increases. The strength tends to decrease as the Mn content increases in the as‐built state. In addition, regardless of the Mn content, the yield strength and ultimate tensile strength tend to decrease owing to the effect of annealing heat treatment. Although the maximum elongation of 18.5Mn and 24Mn does not change significantly upon heat treatment, the maximum elongation of 13Mn is greatly reduced by annealing. The deformation behavior of HMnS is characterized by transformation‐induced plasticity (TRIP) for 13Mn and both TRIP and twinning‐induced plasticity for 18.5Mn and 24Mn.

Effect of Mn content on microstructure and transformation behavior of TiZrHfNiCoCu multi-component high-entropy shape memory alloys

Multi-component Ti16.667Zr16.667Hf16.667Ni25Co10Cu15-XMnX at.% (X = 0, 1, 3, 5 and 7) high-entropy shape memory alloys (HESMAs) were prepared by arc-melting and then microstructures, transformation temperatures, phase constituents and superelastic properties were investigated by scanning electron microscope observation, differential scanning calorimetery, X-ray diffraction and dynamic mechanical analysis in tensile mode, respectively. The microstructure of solution-treated TiZrHfNiCoCuMn HESMAs specimens consisted of (NiCoCuMn)-rich matrix, (TiZrHf)2(NiCoCuMn)-type phase and (TiZrHf)(NiCoCuMn)-type phase. The area fraction of (TiZrHf)2(NiCoCuMn)-type phase increased from 1.7 to 5.1% with increasing Mn content from 0 to 7 at.%. The area fraction of the (TiZrHf)(NiCoCuMn)-type phase increased from 1.9 to 17.2% with increasing Mn content from 3 to 7 at.%. -ΔHmix effect was dominant over ΔSmix and δ effects for phase constitution in TiZrHfNiCoCuMn HESMAs. The martensitic transformation start temperature decreased with the addition of Mn content up to 3 at.% and then increased with increasing Mn content from 3 at.% to 7 at.%. TiZrHfNiCoCuMn HESMAs showed clear superelasticity and the total recovered strain decreased with increasing Mn content.

Crystal chemical investigations of epidote group minerals from two Bulgarian localities: Effects of Mn content and Mn/Fe ratio on the structural peculiarities

The current study presents results of crystal chemical studies of epidote samples from two Central Rhodope localities. Based on the obtained crystal chemical information, the nomenclature of the investigated species has been justified within the IMA-recommended nomenclature of epidote-group minerals. A comparative study has also been accomplished, including data from the present study as well as literature data from selected epidotes possessing similar crystal structural peculiarities. Certain trends have been derived from the transition metal(s) type and content(s) in the most distorted of the three six-coordinated sites (designated as M3) on selected geometrical and crystallographic parameters. The impact of Mn content and Mn/Fe ratio on the structural peculiarities and coloration of the specimens containing this element are discussed in terms of manifestation of the Jahn-Teller effect on the herein-considered epidote phases.

Effect of Mn content on the structure, electromagnetic properties, and electromagnetic wave absorption characteristics in La0.7Sr0.3Mn1+xO3

The perovskite manganese oxide, La0.7Sr0.3Mn1+xO3 (x = −0.4, −0.2, 0, 0.2, 0.4, 0.6, 0.8, 1.0), was synthesized using the solid-state reaction method. A single-phase perovskite structure was obtained at the stoichiometric composition (x = 0). However, with an increase in Mn excess (x > 0), secondary phases of Mn2O3 and Mn3O4 formed and increased, while La2O3 and Sr-rich phases emerged when Mn is deficient (x < 0). The electrical conductivity, permittivity, and permeability of the samples showed significant variations with x, as both charge transport and magnetism originate from the presence of Mn. Complex permittivity (ε', ε") and permeability (μ', μ") spectra were utilized to calculate RL maps based on a transmission line theory. For samples with x ≥ 0, which exhibited relatively high values of ε' and ε", there was no significant absorption of electromagnetic (EM) waves within the measured frequency range (0.1 ≤ f ≤ 18 GHz) due to high EM wave reflection. Conversely, the Mn-deficient samples (x = −0.2, −0.4) demonstrated excellent EM wave absorption properties in the GHz range. This can be attributed to their favorable impedance matching characteristics, resulting from significantly reduced ε' and ε" values in the Mn-deficient samples. Notably, the sample with x = −0.2 exhibited the most outstanding EM wave absorption characteristics, with an RL value of −56 dB at a frequency of 2.33 GHz and a thickness of 7.59 mm. Additionally, it achieved an RL value of −50 dB at 9.8 GHz and 2.90 mm thickness.

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.

Effect of Mn Content on Microstructure, Mechanical Properties, and Corrosion Behavior of Mg-Zn-Gd-Y Alloy

Effect of Mn Content on Microstructure, Mechanical Properties, and Corrosion Behavior of Mg-Zn-Gd-Y Alloy

Effect of Mn content on the high-temperature oxidation behaviors of Mn-substituted-for-Ni alumina-forming austenitic stainless steel

We studied high Mn-substituted-for-Ni AFA steel (Fe-14Cr-(6–12) Mn-10Ni-2.5Al-3Cu-Nb-C AFA steel) oxidation behaviors at 800 °C in air. (6–12) Mn AFA steel formed a three-layered scale: the outer layer is (Mn, Fe)-rich oxide, such as (Mn0·983Fe0.017)2O3, the intermediate is Cr-rich oxide, and the inner layer is Al2O3. (6–8) Mn-AFA steels formed a protective Al2O3 layer with stronger oxidation resistance than (10–12) Mn-AFA steels. The oxidation rate constants of 6Mn- and 8Mn-AFA steels are 1.7 × 10−3 and 2.4 × 10−3 mg2/(cm4·h), respectively, approximately 10 times higher oxidation resistance than that of 10Mn- and 12Mn-AFA steels. (10–12) Mn-AFA steels cannot form a continuous Al2O3 layer. The discontinuous Al2O3 layer allows the elements to diffuse outward, eventually forming Mn-Fe-Nb-rich oxide nodules on the surface of the steel. Mn concentrations with the potential to form protective alumina at 800 °C were identified.

Effects of Mn Content on the Formation of Inclusions in High Aluminum Steel

Effects of Mn Content on the Formation of Inclusions in High Aluminum Steel