MnSi Research Articles

Flow behavior and microstructural evolution of Al-1.2Mg-2.4Si-1.2Cu-0.6Mn alloy during hot compression

Thermal compression tests were conducted on Al-1.2Mg-2.4Si-1.2Cu-0.6Mn alloys with process parameters including deformation temperatures ranging from 400°C to 550°C and strain rates ranging from 0.05 s⁻¹ to 1 s⁻¹. The hot working properties of aluminum alloys were evaluated with intrinsic equations and machining diagrams. The results show that the processing safety zones of the alloy are 425–450℃ and 0.05–0.1 s−1, 450–475℃ and 0.1 s−1-0.5 s−1, and 475–500℃ and 0.5 s−1. The microstructure of the aluminum alloy following hot pressing was investigated through the use of optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and backscattered electron diffraction (EBSD). When the deformation temperature of the alloy is below 450°C, the alloy organization exhibits a greater prevalence of inhomogeneous defects, which manifest as coarser granular regions in the micro-morphology. Upon reaching a deformation temperature of above 525°C, the deformed alloy organization exhibits an evident thermal cracking phenomenon. At the same temperature, an increase in strain rate is accompanied by a decrease in the Mg2Si phase and an increase in the precipitation of the Al(Fe,Mn)Si eutectic phase. Furthermore, the precipitated phase tends to become coarser. The presence of certain Mn-containing nanoparticle dispersions can impede the migration of subgrain grain boundaries, while simultaneously pinning dislocations and accelerating the generation of dislocation entanglement. This also can serve to inhibit the coarsening of the grains to some extent.

Magnetization processes features in the tapes of cobalt-based amorphous alloy

Studies of the amorphous cobalt-based soft magnetic alloy AMAG-172 (Co–Ni–Fe–Cr–Mn–Si–B) from different manufacturers have shown that in the as-quenched state there is nonuniformity of the magnetic characteristics, and therefore the level of internal stresses across the width of the tape produced by MSTATOR (Borovichi) significantly lower. However, similar to the tape produced by NIIMET (Kaluga), there is nonuniformity of the tape in thickness, which contributes to the formation of a bimodal field dependence of magnetic permeability.This may be a consequence of the non-uniform concentration along the width of the tape of hydrogen and oxygen atoms embedded in its surface during interaction with atmospheric vapor and the presence of temperature gradients during the manufacturing process. A stepwise shape of the initial sections of the magnetization curves in the region of the first maximum of magnetic permeability was discovered. The abrupt nature of the magnetization processes in the region of weak fields allows us to conclude that in the samples of tape produced by MSTATOR, the formation of the first maximum of the field dependence is associated with an independent magnetization reversal of the surface layer, while the main layer of the tape participates in the formation of the second maximum. The smoothed shape of the stepped initial section of the magnetization curve of samples produced by NIIMET corresponds to the gradual involvement of the main layer of the tape in the processes of magnetization and remagnetization. A comparison of the hysteresis loops of both parts of the tape, measured in the same magnetic field region, shows that the field shift of the hysteresis loops is associated with the interlayer interaction of the surface and volume of the tape, and the formation of asymmetric hysteresis loops occurs with the participation of the second layer with its gradual involvement in the processes of magnetization and magnetization reversal.

Microstructure and Mechanical Properties of Gas Metal Arc-welded Fe–Mn–Si Seismic Damping Alloy

Microstructure and Mechanical Properties of Gas Metal Arc-welded Fe–Mn–Si Seismic Damping Alloy

A simple route for preparation of TRIP-assisted Si–Mn steel with excellent performance using direct strip casting

A simple route for preparation of TRIP-assisted Si–Mn steel with excellent performance using direct strip casting

Effect of MgO on Crystallization Behavior of CaO–SiO2–Al2O3 Inclusions in Si–Mn Deoxidized Steel During Solidification Stage

Effect of MgO on Crystallization Behavior of CaO–SiO2–Al2O3 Inclusions in Si–Mn Deoxidized Steel During Solidification Stage

Laser Powder Bed Fusion of Fe–Mn–Si based shape memory alloys with high performance at room and cryogenic temperature

A Fe–Mn–Si based alloy with high shape memory effect (SME) and mechanical performance at both cryogenic and room temperature was fabricated by laser powder bed fusion (LPBF) with blended elemental powders. The effect of laser power on the elemental uniformity, microstructure, SME, strength of the as-built sample was investigated. The developed alloy shown superior SME under high laser power, due to the fully transformation of initial bcc phase to the stable fcc phase during the cooling process. The developed Fe–Mn–Si alloy shown high shape recovery rate of 63 % and 92 % after ∼0.05 bending strain at room and cryogenic temperature, respectively. The as-built samples had characteristic microstructure of small fcc phase grains and high density of stacking faut and twins. The as-built sample exhibited room/cryogenic tensile strength as high as 962MPa/1372 MPa, respectively, with considerable plasticity. This work provides foundations for fast development of high performance additively manufactured shape memory alloy (SMA).

Effect of Cr on high-temperature oxidation resistance of Cr–Si–Mn alloyed press-hardened steel during press hardening

It is of great interest to overcome the problem of high-temperature oxidation of press-hardened steels (PHS) in press hardening with a cost-effective Cr alloying strategy. Therefore, since Cr is one of the expensive metals, the effect of Cr (Cr ≤ 3 wt%) content on the oxidation resistance of Cr–Si–Mn alloyed steels was investigated. It was found that Cr–Si–Mn alloyed PHS with a Cr content of about 1.5 wt% or less cannot form a continuous Cr2O3 layer during press hardening. However, when the Cr content reaches around 2.5 wt%, the PHS shows excellent oxidation resistance due to the formation of continuous Cr2O3 and amorphous SiO2 layers, as well as an Mn-rich oxide layer. However, further addition of 0.5 wt% could not significantly improve the oxidation resistance of this PHS. Moreover, the increase in Cr content simultaneously enhances the positive role of Si and Mn in high-temperature oxidation resistance. This work provides new insights into the design of the next generation of PHSs with economical and superior performance.

Crystallization Behavior of the CaO–SiO2–Al2O3–MgO System Inclusions

The crystallization process of low melting point CaO–SiO2–Al2O3–MgO system inclusions during the continuous casting and hot rolling process greatly affects the deformability of inclusions. The effect of Al2O3 and MgO contents on the crystallization characteristics of CaO–SiO2–Al2O3–MgO system melts representing the typical oxide inclusions in Si–Mn deoxidized steels is systematically investigated. The continuous cooling transformation and time–temperature transformation experiments are carried out. The results reveal that the increase of Al2O3 contents restrains the crystallization process of the melt, whereas the crystallization tendency of the melt is promoted with the increase of MgO contents. The precipitated phases are predominately 2CaO·MgO·2SiO2 and 3CaO·MgO·2SiO2, and the primary crystalline phase is unaffected by the changes of Al2O3 and MgO contents. To obtain low melting point plasticized inclusions with limited crystallization ability, it is recommended to control the Al2O3 and MgO contents greater than 15 wt% and below 5 wt%, respectively. The isothermal treatment is suggested to be controlled within a proper temperature range (1175–1250 °C) to decrease the crystallization kinetics. The oxide system's viscosity change is the limiting kinetic factor in the crystallization process, and it can be utilized to predict the system's crystallization tendency.

The electrochemical corrosion performance of aluminum alloys grade 6082-T6 weld repair

This research investigated the corrosion behavior of standard current metal inert gas weld repair for 6082-T6 aluminum alloy using ER5356 filler metal. The new and repaired (NW and RW) welds were studied. The welds comprised the weld metal (WM), the heat affected zone (HAZ) (solid solution and softened zones), and the base metal (BM). The study focused on investigating electrochemical corrosion using polarization and electrochemical impedance spectroscopy (EIS) methods in 3.5% NaCl solutions, especially in HAZ, including metallurgical and mechanical examinations. The BM containing an α-Al matrix with Al(Fe,Mn)Si and Mg2Si phases exhibited the maximum hardness (70–104 HV0.1). The WM hardness decreased (67–76 HV0.1) with the α-Al, β-Mg3Al2, and Mg2Si phases. Despite having comparable phases to BM, HAZs showed lower hardness (Solid HAZ: 70–82 HV0.1) due to more intermetallic phases. The RW’s softened HAZ revealed the minimum hardness (52–63 HV0.1) compared to that of the NW (55–70 HV0.1). Besides, the tensile strength of the RW (179.7 MPa) was also lower than that of the NW (174.4 MPa) because of the reheating effect. The electrochemical corrosion results indicated that the BM exhibited the maximum corrosion resistance (the lowest corrosion current density (icorr), the highest corrosion potential (Ecorr), and the charge transfer resistance (Rct)), followed by the HAZ and the WM, respectively. The softened HAZ demonstrated better corrosion resistance than the solid solution HAZ. Conversely, the over-aging effect reduced the softened zone’s pitting corrosion resistance (Ep) compared to the solid solution zone. The RW exhibited inferior corrosion resistance compared to the NW due to increased intermetallic phases, which was consistent with the mechanical results. However, the RW’s softened HAZ corrosion characteristics were inconsistent with its mechanical properties; its hardness and tensile strength were the lowest, but its corrosion resistance was not. Pitting corrosion was observed on the weld surfaces using the SEM.

Effect of Ferrite Second Phase on Shape Memory Effect of Corrosion‐Resistant Fe–Mn–Si Shape Memory Alloy

At present, Fe–Mn–Si shape memory alloy with high corrosion resistance has become the focus of attention because of its special requirements in some fields. On the basis of Fe–Mn–Si shape memory alloy, a corrosion‐resistant shape memory alloy was designed by adding Cr and other alloy elements. The microstructure characteristics and phase ratio control mechanism of the annealed alloy and the influence mechanism of the second phase (ferrite) and ratio on the alloy memory effect are emphatically studied. The results show that ferrite and austenite are evenly distributed at low annealing temperature, and there is thermal‐induced ε‐martensite at the same time. Appropriate thermal‐induced ε‐martensite can strengthen the austenite matrix, and the shape recovery rate is high at this time. With the increase of annealing temperature, the volume fraction and grain size of ferrite increase, the volume fraction of thermal‐induced ε‐martensite and austenite decreases, and the shape recovery rate decreases, but it is beneficial to improve the corrosion resistance.

Microstructure Characteristics, Texture Evolution and Mechanical Properties of Al–Mg–Si–Mn–xCu Alloys via Extrusion and Heat Treatment

Microstructure Characteristics, Texture Evolution and Mechanical Properties of Al–Mg–Si–Mn–xCu Alloys via Extrusion and Heat Treatment

Shear strengthening of damaged reinforced concrete beams with iron-based shape memory alloy (Fe-SMA) strips: numerical and parametric analysis

Shape memory alloys (SMAs) are metallic materials that are characterized by their ability to restore their original shape after large deformation when activated by heating. This unique property renders SMAs appealing for various civil engineering applications. Iron-based SMAs (Fe-SMAs), including alloys like Fe–Mn–Si, stand out due to their cost-effectiveness and high strength. The primary focus of this research lies in the computational modeling of Fe-SMA strips utilized to reinforce damaged concrete structures. To achieve this, details from an experimental test are leveraged for the computational simulation of real-scale reinforced concrete beams that were first loaded to some level of damage, then released and strengthened, and subsequently retested. The strengthening approach involves the application of external Fe-SMA strips wrapping around the beams. This paper presents an original computational modeling setup that incorporates a switch option for the Fe-SMA material. This feature enables one to use a single simulation platform for the whole process. The significance of this method originates from its capacity to ensure a robust analysis that includes all simulation steps-testing unstrengthened beams, installing and heating Fe-SMA strips, and testing both damaged and strengthened beams—in a single, multi-step analysis. The computational simulation results were compared with the outcomes of the experimental test, revealing an acceptable level of agreement. The findings indicate a substantial increase in both shear strength and ductility as a result of the application of Fe-SMA strips. Additionally, parametric and mesh sensitivity studies were conducted. These aimed to investigate the mesh dependency of the model and to identify the optimal mesh size. Furthermore, variations in the details of the Fe-SMA strips, including thickness, width, quantity, and effect of applied temperature were explored to compare the outcomes of different applications of these strips.

Phase diagrams of oxide system FeO–MnO–MgO–SiO2. Report 2. Triple state diagrams FeO–MnO–SiO2, FeO–MgO–SiO2, MgO–MnO–SiO2

The knowledge of the thermodynamics and phase equilibria of silicate melts FeO–MnO–MgO–SiO2 and solid solutions of silicates of the MnO–MgO–SiO2 system allows us to predict the appearance of non-metallic inclusions in steel. The FeO–MnO–MgO–SiO2 system includes six double and four triple state diagrams of oxide systems. Previously, the state diagrams of binary FeO–MnO, FeO–MgO, FeO–SiO2, MnO–MgO and ternary FeO–MnO–MgO oxide systems were studied. In this work, state diagrams of the FeO–MnO–SiO2, FeO–MgO–SiO2 and MgO–MnO–SiO2 systems were constructed. The calculations used the theory of subregular ionic solutions, which takes into account the dependence of the coordination number on the composition of the melt, quite accurately describes diagrams with two immiscible liquids and is consistent with the experimental data presented in the literature. In the work, the energy parameters of this theory were selected to calculate the activities of the components of the oxide melt of each of the systems under study, as well as the parameter of the theory of regular ionic solutions to calculate the activities of the components of the magnesium-manganese orthosilicate solution |Mg2SiO4, Mn2SiO4|. The data obtained on the state diagrams of the systems included in the FeO–MgO–MnO–SiO2 system will make it possible to establish non-metallic inclusions in equilibrium with the liquid metal in the Fe–Mg–Mn–Si–O system

Effect of MgO on structure and crystallization behavior of CaO–SiO2–Al2O3 inclusions in Si–Mn deoxidized steel

Effect of MgO on structure and crystallization behavior of CaO–SiO2–Al2O3 inclusions in Si–Mn deoxidized steel

Effect of quenching temperature on the austenite stability and mechanical properties of high-strength air-cooled TRIP steel prepared with hot-rolled C–Si–Mn sheets

This paper systematically studies the effect of quenching temperature on the microstructure evolution and the relationship between the microstructure and mechanical properties of air-cooled TRIP steel prepared with C–Si–Mn hot-rolled sheet. The results indicate that when the quenching temperature is lower than (200 °C) or close to (250 °C) the Ms temperature, the martensite transformation mainly occurs during quenching or at early stage of air cooling. When the quenching temperature reaches 300 °C, lathy bainite begins to form. As the quenching temperature increases, the morphology of bainite is transformed from lathy to granular. Bainite transformation during air cooling can promote the C enrichment in austenite, thus improving the thermal stability of the austenite. However, martensite transformation also occurs during subsequent air cooling, and the start temperature of martensite transformation first decreases and then increases with the increase of quenching temperature from 300 °C to 450 °C. The yield and tensile strength of TRIP specimens first decrease and then increase, while the retained austenite content, elongation and product of strength and elongation (PSE) first increase and then decrease. When the quenching temperature is 400 °C, the best elongation and PSE are obtained. The best elongation of 400TRIP specimen is mainly attributed to its highest content and suitable mechanical stability of retained austenite, which is favorable for the expansion of the TRIP effect range. The TRIP specimens prepared with hot-rolled sheet all exhibit ultra-high tensile strength (over 1050 MPa), which is related to the ultrafine ferrite grains, martensite transformation during air cooling and TRIP effect of retained austenite.

Tailoring the stability of iron carbides to enhance the mechanical performances of Fe–C–Mn–Si alloys

Tailoring the stability of iron carbides to enhance the mechanical performances of Fe–C–Mn–Si alloys

High performance Bi–Co–Mn–Si–B-doped ZnO varistors with wide ranging breakdown voltage and high resistance to electrical degradation

A simple ZnO varistor with high resistance to electrical degradation and an adjustable breakdown voltage range of 100–3000 V/mm was developed by adding SiO2 and B2O3 to Bi–Mn–Co-doped ZnO. Samples were fabricated by sintering at 1150 ºC and doped with 0–55 mol% SiO2 to adjust breakdown voltage. High nonlinear index and low leakage current density were confirmed with addition of SiO2; however, severe electrical degradation occurred. Addition of 1 mol% B2O3 successfully improved the resistance to electrical degradation and long-term reliability, due to the formation of homogenous glass-phase Bi–B–O at grain boundaries inhibiting ion migration. A stabilized interface trap with ∼0.6 eV and 10−21 (m2) was found in samples with 1 mol% B2O3.

The shape recovery behavior of compressively deformed Fe–Mn–Si–Cr–Ni alloys

Cylindrical alloys fabricated from shape memory Fe–xMn–5Si–5Ni–yCr were produced by utilizing diverse solid volume fractions through the use of the powder metallurgy and sintering technique. The shape recovery due to compressive force was analyzed and correlated with the volume fractions. A higher concentration of manganese (Mn) will result in a decrease in shape recovery as a result of the formation of oxides, precipitates and unintended intermetallics during the furnace cooling process. The dislocation occurring within and around the grain boundary is another significant factor contributing to the reduction in shape recovery. The increase in chromium (Cr) content reduces the likelihood of dislocation around the grain boundary. The effectiveness of compressive deformation was examined and correlated.

Effects of addition of Er and Zr on microstructure and mechanical properties of Al–Cu–Mn–Si–Mg alloy

Abstract The effects of addition of Er and Zr on the aging precipitation phase and mechanical properties in cast Al–Cu–Mn–Si–Mg alloy were studied. The addition of Er and Zr can refine the as-cast grains. The average grain size of as-cast alloy containing Er and Zr is 140.60 μm, while the average grain size of as-cast alloy without Er and Zr is 168.54 μm. After T6 heat treatment, the yield strength of the alloy containing Er and Zr reached 334.3 MPa, while the yield strength of the alloy without Er and Zr was only 284.3 MPa. After aging the strengthening precipitates of both alloys contain θ′ phase, Q′ phase and T phase. In the alloys containing Er and Zr the Al3(Er, Zr) phase with L12 structure precipitated during the solution process, which reduced the diameter of the θ′ phase during subsequent aging. After T6 heat treatment, the precipitation strengthening contributed 67.09 % and 61.31 % to the total strength of the alloy with Er, Zr and without Er, Zr, respectively.

Influence of Mn–Si elements on the kinetics of oxidative phase transformation under continuous cooling conditions and modeling study

Influence of Mn–Si elements on the kinetics of oxidative phase transformation under continuous cooling conditions and modeling study