Mn Alloy Research Articles

Improved mechanical and corrosion properties through high-pressure phase transition in a biodegradable Zn-1.5Mn alloy

Zn-Mn alloys are considered promising biodegradable metals for orthopedic applications due to their large elongation and favorable osteogenicity. However, the corrosion rate of Zn-Mn alloys could be improved to meet the degradation requirement for orthopedic implants. In this study, a Zn-1.5Mn alloy was prepared via high-pressure solid-solution (HPSS) treatment at 5 GPa and 380 °C for 1 h to cast ingots. Microstructural evaluation revealed the HPSS treatment caused a phase transition from a ζ-MnZn13 phase to an ε-MnZn3 phase. The electrode potential difference between the ε-MnZn3 and the α-Zn was significantly larger than between the ζ-MnZn13 and the α-Zn, leading to an accelerated corrosion rate of the HPSS-treated alloy. It showed an electrochemical corrosion rate of 0.343 mm/y and an immersion degradation rate of 0.028 mm/y, while the as-cast (AC) Zn-1.5Mn displayed an electrochemical corrosion rate of 0.216 mm/y and an immersion degradation rate of 0.026 mm/y. Further, the HPSS-treated Zn-1.5Mn exhibited a compressive yield strength of 202 MPa and a microhardness of 83.48 HV. In addition, the HPSS-treated Zn-1.5Mn exhibited a cell viability toward human umbilical vein endothelial cells (HUVEC) comparable to its AC and atmospheric pressure solid-solution-treated (APSS-treated) counterparts toward HUVEC, along with improved antibacterial activity.

Enhanced mechanical performance and tailored degradation characteristics of rolled Zn-0.8Li-0.4Mn alloy

The application of biodegradable Zn-based vascular alloy stents proves to be an ideal solution for addressing cardiovascular diseases. In this work, a Zn-0.8Li-0.4Mn alloy is designed with no biological toxicity, and optimized microstructure and properties through a hot rolling process. The resulting alloy shows a combined enhancement in both mechanical strength and resistance to corrosion. Noteworthy is the effectiveness of rolling deformation in refining alloy grains, promoting the uniform distribution of precipitates, and enhancing strength and ductility. After 90 % deformation, the Zn-0.8Li-0.4Mn alloy demonstrates excellent mechanical properties, with peak yield strength and ultimate tensile strength of 406.0 MPa and 449.1 MPa, respectively, and elongation exceeding 75 %. Corrosion studies indicate a relationship between the degradation rate increase and grain refinement, with the primary corrosion mechanism being pitting corrosion. The corrosion product Li2CO3 exhibits high stability, providing a passivation effect on the alloy surface. This work establishes a theoretical foundation and practical reference for the development of new biodegradable Zn-based alloys tailored for biomedical applications.

Optimization of mechanical, corrosion properties and cytotoxicity of biodegradable Zn-Mn alloys by synergy of high-pressure solidification and cold rolling process

Zinc (Zn) and Zn-based alloys are biodegradable materials, that have recently gained significant research attention due to their moderate degradation rate and good biocompatibility. However, their clinical applications are limited by their inferior mechanical properties. In this study, Zn-0.5Mn, Zn-1.0Mn, and Zn-1.5Mn (wt%) alloys were prepared via high-pressure solidification (HPS) and cold rolling (CR) procedures. Further, the microstructure, mechanical properties, corrosion behavior, and in-vitro cytotoxicity of these Zn-Mn alloys were systematically investigated. The results revealed that their yield strength (σys) and ultimate tensile strength (σUTS) enhanced significantly after synergy of HPS-CR treatment compared to CR alone. Notably, among these alloys, the Zn-1.5Mn alloy exhibited the highest σys and σUTS after HPS-CR, at 296.4±5.4 MPa and 322.6±3.5 MPa, respectively. The primary reason for this phenomenon is attributed to the combination of grain refinement and solid solution strengthening performance. Furthermore, these newly designed biodegradable Zn-Mn alloys exhibited appropriate in-vitro degradation rates and acceptable in vitro cytocompatibility when tested in Hanks' solution.

Electrolytic recovery of metals from lithium battery cathodes in moisture-tolerant molten hydroxide salt

Lithium-ion battery recycling offers an opportunity to develop innovative technologies to close the loop on the battery materials cycle and increase the resilience of the battery supply chain. Here we demonstrate a two-step pyroelectrochemical method for producing mixed-metals from lithium-ion cathodes in a molten hydroxide salt. Mixed metal oxides in the form of insoluble lithium-ion cathode materials of LiNi0.6Mn0.2Co0.2O2 (NMC622) and spent lithium-ion battery materials (black mass) were electrochemically reduced to a soluble form and dissolved into a molten hydroxide salt bath. Electrochemical characterization of the process salt indicated accumulation of dissolved transition metals in the salt. A separate cathode was used to produce alloys of Ni, Mn, and Co electrochemically from the dissolved lithium-ion cathode materials. Characterization by scanning electron microscopy fitted with an energy dispersive X-ray spectrometer showed transition metals present in the cathode materials were recovered at the separate cathode. This approach represents a scalable, low temperature pyroelectrochemical process that can potentially reduce the cost and close the loop of battery cathode recycling.

Hysteresis gap-shrinking and structural effects of minor Al and Ti modifications on binary CuAl-based high-temperature shape memory alloys

Cu-based shape memory alloys (SMAs), except for exhibiting shape recovery, superelasticity, and high damping, are desirable because these smart materials have higher electrical and thermal conductivity and much lower prices than NiTi SMAs. However, they also have some downsides in mechanical strength and brittleness (mostly stemming from their coarse grain structure) and thermal instability. Therefore, adding some grain refining elements to these SMAs to improve their shape memory effect (SME), and thermal, structural, and mechanical properties is a widespread and simple way that significantly affects their martensitic phase transitions, structure, and mechanical properties. One of these grain-refining elements is titanium. Its thermal conductivity is lower than those of Cu and Al elements and has a low solubility in Cu-matrix. Besides the effects of small Al variations, the use of minor amounts of titanium in binary CuAl-base alloys can show impressive effects on all characteristics of these shape memory alloys, such as shape memory effect properties, martensitic transformation kinetics parameters, and microstructural features. In this research work, CuAlTi ternary high-temperature shape memory alloys (HTSMAs) with new compositions were produced by the arc melting method without a complicating use of Mn or Ni components in usual ternary CuAlMn and CuAlNi shape memory alloys. Thermal analyses of the prepared samples of the alloys were investigated by using differential scanning calorimetry (DSC) and differential thermal analysis (DTA) measurements. In contrast, x-ray diffraction (XRD) test results and optical micrographs were used for analyzing the structure of the alloy samples. The effect of different amounts of low soluble and grain refining Ti element on the binary CuAl alloy system was investigated.

Effects of Sn and Mn additions on microstructural characteristics and tensile properties of Mg-1Gd alloy

Effects of Sn, Mn, and their combined additions on microstructural characteristic and tensile properties of extruded Mg-1Gd (G1) alloy are explored. Compared to the sole Sn or Mn addition, an excellent grain refining is happened with the Sn and Mn combined addition. The average grain size of G1, Mg-1Gd-0.8Sn (GS10), Mg-1Gd-0.7Mn (GM10) and Mg-1Gd-0.8Sn-0.7Mn (GSM100) alloys is ∼21.3, 10.1, ∼12.8 and ∼6.8 μm, respectively. The sole Mn addition enhances the strength and ductility of G1 alloy. The forming the fine α-Mn particles and grain refining are attributed to the improved properties of GM10 alloy. The sole Sn addition increases the yield strength of G1 alloy along extrusion direction (ED), but it decreases along transverse direction (TD), The inhomogeneous distribution of coarse GdMgSn particles and formation of TD-split texture should play an important role. The combined effects of Sn and Mn additions guarantee high strength-ductility synergy of GSM100 alloy. The GSM100 alloy exhibits the ultimate strength, yield strength and ductility of ∼276, ∼158 MPa and 24.7 % along ED, and ∼253, ∼157 MPa and 17.5 % along TD, respectively. The jointly effect of the fine grains, a lot of fine GdMgSn and α-Mn particles, the texture weakening and Sn solute atom contributes to the enhancement of properties of GSM100 alloy.

Effects of alloying element on the interface stability of fcc-Fe/NbC by first principles investigation

Interfacial segregation engineering is widely used as a means of regulating the strength and toughness of materials. In this paper, the effect of alloying elements on the interfacial segregation and interfacial bonding properties of fcc-Fe/NbC is investigated with the precipitated phase NbC in austenitic heat-resistant steel. The results show that there are eighteen interfacial configurations between the fcc-Fe and NbC phase, and the stability of the interface with Nb terminal is better than that of C terminal according to the calculation results of separation work and interface energy. Al atom is easy to segregate on the surface of austenite, while the alloy elements Mo, Nb, Cr, Ti, Mn, Y and Zr tend to segregate in the austenite matrix. The segregation of alloy elements Mo, Nb, Cr and Ti can enhance the hybridization between the d orbits of Fe and Nb atoms at the interface, thus promoting the bonding strength of the interface, while the segregation of Mn, Al, Y and Zr reduces the covalent interaction of the interface atoms, which weakens the bond strength at the interface. The above results have important practical significance for improving and regulating the composition and interfacial properties of heat-resistant steels.

Microstructure and mechanical properties of extruded Mg–Zn–Mn–Ca alloys

In this work, the influence of Mn and Ca doping on the microstructure and mechanical properties of Mg–3Zn, Mg–3Zn-0.5Mn, and Mg–3Zn-0.5Mn-1.2Ca alloys is systematically investigated. The addition of Mn elements is shown to exert no obvious effect on the microstructure of as-cast, as-homogenized, and extruded Mg–3Zn alloys. In contrast, the introduction of Ca into the extruded Mg–3Zn-0.5Mn alloy promotes the formation of nano-sized compounds and enhances grain refinement compared to the other two alloys. The extruded Mg–3Zn-0.5Mn alloy exhibits the higher yield strength (YS, 155 MPa) and ultimate tensile strength (UTS, 183 MPa) but the lower elongation (13%) than the extruded Mg–3Zn alloy (YS of 130 MPa, UTS of 175 MPa, and elongation of 25%). The improved strength of the extruded Mg–3Zn-0.5Mn alloy is mainly attributed to the refined grains, while both the lack of twinning deformation and strong texture result in ductility loss. The most optimal combination of strength and ductility is achieved in an extruded Mg–3Zn-0.5Mn-1.2Ca alloy (YS of 180 MPa, UTS of 250 MPa, and elongation of 26%). This suggests that fine grains and high volume fraction of nano-sized MgZn2 compounds contribute mainly to the strength of Mg–3Zn-0.5Mn-1.2Ca alloy. Although the grain refinement also facilitates the suppression of twinning in the extruded Mg–3Zn-0.5Mn-1.2Ca alloy, the weak texture and fine homogeneous grains are conducive to the high ductility.

Growth of a Single MnCr2O4 Spinel on Ni–25Cr–1.5Mn Alloy by the Rhines Pack Method and Photoelectrochemical and Raman Signatures of MnCr2O4 Spinel

Growth of a Single MnCr2O4 Spinel on Ni–25Cr–1.5Mn Alloy by the Rhines Pack Method and Photoelectrochemical and Raman Signatures of MnCr2O4 Spinel

Effect of intermediate processing treatment on the structure and mechanical properties of Al–4 wt%Cu–3 wt%Mn alloy manufactured by electromagnetic casting followed by high-pressure torsion (HPT)

In this work, a thermally stable model Al–4Cu–3Mn (wt%) alloy has been manufactured by electromagnetic casting (EMC), followed by compression, intermediate heat treatment and high-pressure torsion (HPT). Structural changes of the alloy during subsequent processing stages have been analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the X-ray diffraction (XRD). The results indicate that variations in the intermediate heat treatment temperature of the compressed samples lead to a significant difference in strain hardening and thermal stability after HPT. According to microstructure investigations the hardening of samples processed by HPT resulted from formation of mixture of grains and subgrains with high dislocation density as well as mechanical fragmentation of eutectic Al2Cu particles and precipitation of nanoscale Mn-rich dispersoids which are identified as Al6Mn. The intermediate heat treatment of the EMC rod at 350 ºC for 3 hours and heat treatment of HPT sample at 250 ºC for 5 hours exhibited the best mechanical properties in terms of ultimate tensile strength (UTS), yield strength (YS) and elongation (El), reaching 610 MPa, 560 MPa and 10 % respectively. At the same time intermediate annealing at 450 °C makes the HPT processing ineffective.

Fatigue strength and fatigue crack initiation mechanism in non-combustible Mg-4%Al-1%Ca-0.2%Mn alloys and its TIG and MIG weld joints

Fatigue strength and fatigue crack initiation mechanism in non-combustible Mg-4%Al-1%Ca-0.2%Mn alloys and its TIG and MIG weld joints

Finite Element Modeling and Experimental Verification of a New Aluminum Al-2%Cu-2%Mn Alloy Hot Cladding by Flat Rolling

The roll bonding of an experimental Al-2%Cu-2%Mn alloy with technically pure 1050A aluminum at true deformations of 0.26, 0.33 and 0.40 has been simulated using the QForm 10.3.0 FEM software. The flow stress of the Al-2%Cu-2%Mn alloy has been measured in temperature and strain rate ranges of 350–450 °C and 0.1–20 s−1, respectively. The simulation results suggest that the equivalent strain in the cladding layer is more intense than that in the base layer, reaching 1.0, 1.4 and 2.0 at strains of 0.26, 0.33 and 0.40, respectively. The latter fact favors a decrease in the difference between the flow stresses of the rolled sheet layer contact surfaces by an average of 25% at the highest strain. The experimental roll bonding has achieved good layer adhesion for all the test samples. The average peeling strength of the samples produced at strains of 0.26 and 0.33 proves to be 12.6 and 18.4 N/mm, respectively, and at a strain of 0.40, it has exceeded the flow stress of the 1050A alloy cladding layer. The change in the rolling force for different rolling routes has demonstrated the best fit with the experimental data.

Effects of solution aging treatments on microstructure features, tensile properties and low-cycle fatigue behavior of Ti-6.2Al-4.26Mo-1.33Mn alloy

High-performance titanium alloy fasteners play an important role in the aerospace industry as important general basic parts. This work developed a high-elastic-modulus Ti-6.2Al-4.26Mo-1.33Mn alloy with good balance of strength and plasticity through regulating its primary equiaxed α (αp) phase with solution aging treatment. The influence of αp on the tensile properties and low-cycle fatigue (LCF) behavior of the alloy was investigated systematically, and the crack propagation mechanism of fatigue fracture of titanium alloy was revealed. The results show that with increasing solution temperature, the content of αp phase decreases from 43.6 % to 15.1 % in the range of 825 °C–925 °C, and the LCF life is increased by almost 2 times. However, the size of αp phase is almost unchanged with a diameter of about 2.3 μm. With the increase in solution temperature, the tensile strength of the alloy is improved, while the plasticity decreases gradually. At the solution temperature of 875 °C, the ultimate tensile strength (UTS) of the alloy is 1350 MPa, which is 18.6 % higher than the as-forged alloy, with an elongation (El) of >7 %. Moreover, the fatigue performance is also significantly improved, which is associated with the reduced αp phase that was characterized to act as crack initiations and crack propagation path.

Study on the electromagnetic properties and microwave absorption properties of Co2Si by non-magnetic metal Cu and Mn single doping

In this study, Co2Si and Co2Si-doped powder materials with different Cu,Mn proportions were prepared by mechanical alloying and thermal sintering. The effects of Cu,Mn doping on the crystal structure, magnetic properties, and microwave absorption properties of Co2Si were investigated. The results showed that all the sample peaks obtained by XRD measurement were consistent with the standard card (ICDD: 98–005–2281) of Co2Si.The Ms values corresponding to 2 at%, 4 at%, and 8 at% Cu doping were 25.79 emu/g, 23.79 emu/g, and 21.75 emu/g, respectively. The saturation magnetization of Co2Si samples doped with 2 at%, 4 at% and 8 at% Mn was 8.26 emu/g, 20.33 emu/g and 14.65 emu/g, respectively.The doping of Cu significantly improved the comprehensive absorption performance of Co2Si alloy, and the lowest reflection loss was obtained when Cu was doped with Co2Si alloy, with an RLmin value of -67.61 dB and an EAB of 2.40 GHz. The comprehensive absorption performance of Mn doped Co2Si was also improved, and the RLmin value of Mn doped with 4 at% was -67.04 dB, and the EAB was 2.39 GHz.This is because that the small Co2-xMxSi (M=Cu,Mn) alloy can produce multiple reflection and scattering effects, which increase the propagation path of the electromagnetic wave and optimize the impedance matching characteristics of the material.

Enhancing Microstructural, Thermal, Mechanical, and Corrosion Response of a Bio/Eco‐Compatible Mg–2Zn–1Ca–0.3Mn Alloy Using Two Types of Cryogenic Treatments

Biocompatible Mg–2Zn–1Ca–0.3Mn is synthesized using the disintegrated metal deposition process and subjected to two types of cryogenic treatments (refrigeration [RF] at −20 and −196 °C using liquid nitrogen) with a target to improve microstructural, thermal, mechanical, and electrochemical responses. The material exhibits densification and grain refinement after these treatments, which improves the physical, thermal, compressive, and corrosion responses. While both RF and liquid nitrogen exposures improve the overall combination of properties, overall improvement in properties is best met with RF treatment at −20 °C. In the results of this work, the efficacy of low energy option (RF) is convincingly established rather than liquid nitrogen exposure (as conventionally practiced) to enhance microstructure and properties.

Investigation of the microstructural behavior of Al–Mg–Si(X)–Mn aluminum alloys based on biaxial hot tensile tests

This study investigates the microstructural behavior of laboratory-produced Al–Mg–Si(X)–Mn aluminum alloys, focusing on the influence of varying Si content during biaxial hot tensile testing. Alloys with Si contents of 0.7%, 0.9%, and 1.3% were subjected to biaxial deformation at temperatures of 200 °C, 300 °C, and 400 °C. Using digital image correlation analysis, the impact of Si content on microstructural evolution under biaxial tensile loading was analyzed. Force–displacement analysis revealed a consistent inverse relationship between temperature and the maximum force required to initiate strain. At the temperature of 200 °C, the Al–Mg–Si(1.3)–Mn alloy required a maximum force of 1500 N, while at the temperature of 400 °C this force decreased to 900 N. The degree of anisotropy varied, with higher Si alloys exhibiting increased resistance to deformation in the transverse direction. In particular, the Al–Mg–Si(1.3)–Mn alloy showed pronounced strain anisotropy, with large major true strain φ1 values reaching up to 0.32 at 400 °C, compared to 0.26 at 300 °C and 0.2 at 200 °C. Microstructural analysis using electron backscatter diffraction (EBSD) and energy dispersive X-ray spectrometry (EDS) showed minimal changes at low temperatures, while increased dislocation density and grain boundary distortion were observed at elevated temperatures. The β-Mg2Si precipitates, influenced by Si content and temperature, significantly affected the mechanical properties. In the Al–Mg–Si(0.7)–Mn alloy, precipitates were predominantly 1–3 µm in diameter, whereas in the Al–Mg–Si(1.3)–Mn alloy, precipitates grew to 4–8 µm at higher Si content. These findings provide critical insights into the mechanical response and deformation mechanisms of aluminum alloys under biaxial tensile conditions, essential for optimizing material performance in engineering applications.Graphical abstract

High‐temperature oxidation of Cu–Al–Ni–Mn shape‐memory alloy

AbstractThe isothermal oxidation behavior of the Cu‐11.35Al‐3.2Ni‐3.5Mn (wt.%) shape‐memory alloy (SMA) in the temperature range of 500–900°C in oxygen was studied using the thermogravimetric (TG) method. TG curve showed that the alloy has parabolic isothermal oxidation characteristics. The effect of oxidation on the surface morphology and chemical composition of the Cu–Al–Ni–Mn alloy was determined by scanning electron microscopy, energy‐dispersive spectroscopy, and X‐ray photoelectron spectroscopy (XPS) analyses. The oxidation rate of SMA increases up to 700°C, remains stable at 800°C, and increases again up to 900°C. The XPS analysis identified that the corrosion products mainly contained MnO2, MnO/Mn2O3, and Al2O3.

Microstructure and Mechanical Properties of Mg-Al-La-Mn Composites Reinforced by AlN Particles.

The Mg-Al-RE series heat-resistant magnesium alloys are applied in automotive engine and transmission system components due to their high-temperature performance. However, after serving at a high temperature for a long time, the Al11RE3 phase coarsened and even decomposed, while the Mg17Al12 phase grew and dissolved, which limits the service temperature of Mg-Al-RE series heat-resistant magnesium alloys to a maximum of 175 °C. In this study, a new preparation method for in situ AlN particles was presented. The AlN/Mg-4Al-4La-0.3Mn composites were prepared by a master alloy and casting method. The effects of various contents of AlN (0.5-3.0 wt.%) on the microstructure and mechanical properties of the Mg-4Al-4La-0.3Mn (AE44) alloy at room (25 °C) and high temperatures (150-250 °C) were investigated. Microstructure analysis revealed that the inclusion of AlN led to a reduction in both the grain size and second phase size in the AE44 alloy, while also improving the distribution of the second phase. The average grain size, Al11La3 phase, Al2La phase, and Al3La phase of the 2.0 wt.% AlN/AE44 composite were 135.7, 9.6, 1.9, and 12.6 μm, respectively, which were significantly lower than those of the AE44 matrix alloy (179.8, 12.6, 3.3, 17.8 μm). The refinement was attributed to the ability of AlN particles to serve as heterogeneous nucleation cores for α-Mg and, at the same time, impede the growth of the solid-liquid interface, eventually leading to grain refinement. With the increase in the AlN content, the mechanical properties of composites initially exhibited an increase at both room and high temperatures, followed by a subsequent decrease. When the AlN content was 2.0 wt.%, the composite exhibited optimal strength and plasticity matching. At room temperature, the TYS, UTS, and EL values of the 2.0 wt.% Mg-4Al-4La-0.3Mn composite were 96 MPa, 175 MPa, and 7.0%, respectively, which were increased by 26 MPa, 27 MPa, and 0.7% when compared with the base alloy. The TYS of the 2.0 wt.% Mg-4Al-4La-0.3Mn composite at 150 °C, 200 °C, and 250 °C were 17 MPa, 14 MPa, and 22 MPa higher than those of the matrix alloy, respectively. The main strengthening mechanisms were second phase strengthening, load transfer strengthening, and thermal mismatch strengthening. At elevated temperatures, AlN particles effectively pinned the grain boundaries, inhibiting their migration, and hindered dislocation climbing, resulting in excellent mechanical properties of the composites at high temperatures. This study contributes to the advancement of in situ AlN particle preparation methods and the exploration of effects of AlN on the properties and microstructure of Mg-Al-RE alloys at high temperatures (150-250 °C).

Strain Hardening in Dilute Binary Al–Cu, Al–Zn, and Al–Mn Alloys: Experiment and Modeling

During thermo-mechanical processing, dissolved alloying elements have a huge impact on the microstructure evolution by influencing the overall dislocation storage rate. Especially, for non-heat treatable Al alloys, the effects of strain-hardening and solid solution strengthening are of significant practical interest. In the present work, a detailed study of the room temperature work-hardening behavior of binary Al–Cu, Al–Zn, and Al–Mn alloys with varying solute concentrations is carried out. Stress–strain curves at different strain rates are recorded and computationally analyzed by an advanced 3-Internal-Variables-Model (3IVM) approach for the dislocation density evolution. The initial strengthening rate is examined as a function of the solute concentration.

Mechanical properties and microstructure of magnesium alloy with in situ formed Al2RE phases

The advancement of magnesium alloys has historically faced challenges due to their inherently low modulus and the inverse relationship between modulus and ductility. In this study, an Mg-15Gd-8Y–11Al-0.3Mn alloy containing Al2RE phases was developed through an in-situ synthesis process, exhibiting exceptional mechanical properties, including a high elastic modulus of 57.6 GPa coupled with a satisfactory elongation of 7.3 %. The findings indicate the presence of polygonal Al2RE phases of varying sizes within the alloy, with α-Mg observed in some Al2RE phases, forming a coherent interface. The grain size of the alloy was refined, and the dimensions of the Al2RE particles were reduced through the extrusion process. The effective strain transfer between α-Mg and Al2RE, facilitated by the coherent interface, endowed the alloy with commendable ductility, even at a substantial Al2RE volume fraction of 23 %. Furthermore, the formation of the Al2RE phase was identified as the key contributor to the alloy's enhanced modulus. This study provides novel insights for the engineering of high-modulus magnesium alloys, thereby paving the way into their broader industrial application.