Al-Mn Alloys Research Articles

Characterizations of micro-nano structure and tensile properties of a Sc modified Al Mn alloy fabricated by selective laser melting

In this work, bulk deposits of a Sc modified Al-Mn-Fe-Si alloy were prepared by selective laser melting (SLM), and the microstructural characteristics and tensile properties of the deposits were analyzed. The as-deposited sample presented a multiscale microstructure consisting of epitaxial columnar grains with width of 30–140 μm, in which there exist α-Al dendrite arrays with average primary dendrite arm spacing of 0.34 μm, and interdendritic nanoscale α-Al + Al6(Mn,Fe) divorced eutectic. After an aging treatment, Al6(Mn,Fe) transformed into Al12(Mn,Fe)3Si, and its morphology gradually evolved from skeleton into particle. Meanwhile, needle-like AlMnSi precipitated and grew up in the α-Al dendrite trunk. The ultimate tensile strength increased from 349 ± 9 MPa in the as-deposited state to 430 ± 3 MPa after aging at 300 °C. However, it dropped to 358 ± 1 MPa when the aging temperature increased to 350 °C. The addition of Sc caused precipitation strengthening of secondary Al3Sc after aging treatment, but the grain refinement effect of primary Al3Sc was inhibited since Sc tended to segregate at the frontier of the Mn-containing pre-precipitates.

Evolution of micro-chemistry during solidification and homogenisation of AA 3xxx aluminium–manganese alloys

An important aspect of the characterisation of non-heat-treatable Al alloys is the constitution of the material in terms of its alloying elements in solid solution and, in turn, volume, size, morphology and species of second-phase particles. These constitutional characteristics, conveniently summarised as micro-chemistry, have an impact on physical and mechanical materials properties of Al semi-finished products. In the present study, the evolution of micro-chemistry in the Al–Mn alloys of the AA 3xxx series during solidification and homogenisation is analysed. Especially, we focus on the impact of additional alloy elements, including Si, Mg and Cu, on the phase selection during solidification and the changes in solute level and volume, size and type of second-phase particles during subsequent homogenisation.

Inverse Magnetocaloric Effect Related to the Magnetostructural Phase Transition in Quaternary Ni–Co–Mn–Al Alloy

Inverse Magnetocaloric Effect Related to the Magnetostructural Phase Transition in Quaternary Ni–Co–Mn–Al Alloy

An Evaluation of the Influence of Forward Slip on the Corrosion Behavior of Aluminum-Manganese Alloys

The tribological influence of hot rolling parameters, such as the work roll roughness, roll speed, and the number of rolling passes on the surface quality of rolled aluminum alloys, has been a subject of interest for the wrought aluminum industry. A hot rolling tribo-simulator was used to investigate the effect of forward slip on the surface damage induced by the rolling operation and the subsequent corrosion behavior of the Al-Mn alloys. A two-pass hot rolling schedule was conducted at 500–540 °C for forward slip levels of − 4, 1, 7, and 13% using an AISI 52100 steel work roll with a surface roughness (Ra) of 0.01 µm. Characterization of the rolled surfaces using scanning electron microscopy (SEM) revealed hot rolling-induced damage in the form of microcracks, nanocracks, and MgO coverage, which was more prominent for higher forward slips. Corrosion tests were subsequently conducted on the rolled Al-Mn specimens by immersion in a 0.5 wt.% NaCl solution. These tests showed greater corrosion-covered surface areas on samples rolled at lower forward slips. This relationship between the forward slip and corrosion behavior was due to the extent of surface damage induced at varying forward slip levels. The preferential corrosion mechanism was observed to be due to the dissolution of the MgO-rich near-surface microstructures induced during hot rolling.

Corrosion inhibition of AA3003 aluminum alloy by self-assembled layers of myristic acid

PurposeThis paper aims to prepare highly hydrophobic films on aluminum AA3003 using myristic acid (MA) and evaluate its corrosion protection efficiency in a low-chloride solution.Design/methodology/approachThe aluminum surface was initially treated with boiling water to develop a porous nanostructure, and then surface modification was carried out in ethanolic solutions with different concentrations of MA. The surface morphology, wetting behavior and film composition were first characterized, and then, the corrosion behavior was evaluated with electrochemical techniques.FindingsThe best hydrophobicity and corrosion resistance were obtained with 50 mM of MA. For such concentration, a water contact angle of 140° and protective efficiency of 96% were achieved. A multilayer structure was revealed by scanning electron microscope and X-ray photoelectron spectroscopy.Originality/valueThe results of this work shed light on the anticorrosion performance of fatty acid self-assembled multilayers on the surface of Al–Mn alloys.

Investigations on machining characteristics and chip morphology in turning Al-Mn (AM) alloy using finite element simulation

Finite element analysis has become an indispensable tool, often used in research and development, to provide valuable insights into the process. The studies in the metal cutting area mostly employ the Finite element method (FEM) due to its ability to highlight the physics involved in chip formation and the range of force generated in the cutting zone. The study involves investigations by adopting the Johnson-Cook (JC) constitutive model with energy-based damage criteria to simulate the turning of a fabricated AM (Mg alloy: 7 wt%Al-0.9 wt%Mn) alloy. For the FEM, the JC and Damage model constants are calculated using inverse identification methodology. The results obtained on the cutting force (Fc), cutting temperature (Tc), and chip-thickness (tc) at different combinations of turning parameters were analyzed and compared with the experimental values. The Predicted data was in line with the experimental data, and a variation of mostly less than 12% was observed. Thus, establishing the efficacy of inverse identification method. Further, the obtained results exhibit the significant influence of turning parameters on Fc(N), Tc(°C), and tc(mm) and enunciates crucial facts related to the AM alloy's machinability.

Microstructure and magnetic properties of (Mn54Al46)98C2 magnets fabricated by liquid-phase sintering with the Mn65Ga35 as an additive

MnAl(C) alloys are widely considered as potential candidates of rare earth-free permanent magnets. Fabrication of MnAl(C) magnets remains an intensive research topic. In this work, liquid-phase sintering is primarily explored to prepare MnAl(C) magnets by sintering (Mn54Al46)98C2 with Mn65Ga35 as an additive. The sintering temperature of 1273 K ensures the Mn65Ga35 in liquid-state and (Mn54Al46)98C2 in solid-state. The liquid-phase sintering leads to a noticeable densification effect on the magnets, in which the internal porosity is significantly reduced. As the weight percentage of Mn65Ga35 increases from 0 wt.% to 40 wt.%, the remanence magnetization μ0Mr increases from 1.44 kGs to 1.83 kGs, the coercivity Hc increases from 1.08 kOe to 1.52 kOe, and the energy product (BH)max increases from 0.25 MGOe to 0.45 MGOe. The Hc increase is explained based on the nucleation model. This work might provide a possible approach to fabricate MnAl(C) magnets.

Keyhole mode induced simultaneous improvement in strength and ductility of Sc modified Al–Mn alloy manufactured by selective laser melting

The effect of melting modes on microstructure evolution and tensile properties of selective laser melted (SLM-ed) Sc modified Al–Mn alloy (Al–5Mn-0.6Sc) is investigated in this work. With the transition of melting mode from conduction to keyhole by coinstantaneous increasing the laser power from 200 W to 380 W and the scanning speed from 800 mm/s to 1400 mm/s, the columnar grain width significantly decreases by 88% from 34.9 μm to 4.2 μm. Consequently, the yield strength and the elongation increase simultaneously from 266 MPa and 10% to 308 MPa and 17%, which increase by 16% and 70%, respectively. The refinement and orientation diversification of the grains caused by keyhole mode simultaneously improve the strength and elongation by inducing the Hall-Petch effect and enhancing the crack path tortuosity. This work reveals the feasibility and the mechanism of changing melting mode acts as a method to regulate the SLM-ed microstructure and mechanical properties.

Electrochemical production of Al–Mn alloys during the electrodeposition of aluminium in a laboratory cell

This study reports the direct production of an aluminium–manganese alloy during aluminium electrolysis in fluoride-based melts. Experiments were conducted in a laboratory cell dedicated for current efficiency measurements. The temperature was varied from 965–980 °C at a cathodic current density (CCD) of 0.9 A/cm2 and a cryolite ratio (CR) of 2.2. The manganese content was up to 3.0 wt%. Manganese was added in the form of Mn2O3. Bath samples were collected regularly and analyzed with ICP-MS to observe the decay of manganese during electrolysis. It was possible to produce Al-Mn alloys of up to 21 wt. % Mn. Current efficiency for the electrodeposition of Al–Mn alloy was estimated to be in the range of 93%. Current efficiencies with respect to aluminium were estimated. The solidified surfaces of the metal deposits were mostly flat, but some were deformed.

Aluminothermic Reduction of Manganese Oxide from Selected MnO-Containing Slags.

The aluminothermic reduction process of manganese oxide from different slags by aluminum was investigated using pure Al and two types of industrial Al dross. Two types of MnO-containing slags were used: a synthetic highly pure CaO-MnO slag and an industrial high carbon ferromanganese slag. Mixtures of Al and slag with more Al than the stoichiometry were heated and interacted in an induction furnace up to 1873 K, yielding molten metal and slag products. The characterization of the produced metal and slag phases indicated that the complete reduction of MnO occurs via the aluminothermic process. Moreover, as the Al content in the charge was high, it also completely reduced SiO2 in the industrial ferromanganese slag. A small mass transport of Ca and Mg into the metal phase was also observed, which was shown to be affected by the slag chemistry. The obtained results indicated that the valorization of both Al dross and FeMn slag in a single process for the production of Mn, Mn-Al, and Mn-Al-Si alloys is possible. Moreover, the energy balance for the process indicated that the energy consumption of the process to produce Mn-Al alloys via the proposed process is insignificant due to the highly exothermic reactions at high temperatures.

Bubble-induced formation of new intermetallic compounds in an Al–Mn alloy during heating observed by synchrotron radiography

Formation of intermetallic compounds (IMCs) is observed for the first-time during heating of an Al–10 wt% Mn alloy by synchrotron radiography. We reveal that such “abnormal” behavior is closely associated with coalescence of bubbles, which induces concentration fluctuation of Mn solute. When the local solute concentration exceeds its saturability, nucleation and precipitation of IMCs occur in the melt. A mathematical model is established to describe the supersaturation fluctuation of Mn solute during bubble coalescence. The merged bubble can push the newly-formed IMCs to move. Bubble-induced formation of IMCs is an important supplementary to the existing formation mechanisms of IMCs in Al–Mn alloys.

Recent developments of manganese-aluminium as rare-earth-free magnets

This article reviews findings and progresses in the past decade on manganese-aluminium (MnAl) based magnets as the interest has been revived to fulfill their potential as commercial magnets. The challenges in developments of these rare-earth-free magnets are to acquire a high remanence and coercivity from the ferromagnetic τ-phase in MnAl alloys. To this end, the phase transformation to this τ-MnAl with L10 body centered tetragonal structure has been promoted by a variety of methods and a few percents of carbon (C) is often added to prevent the phase decomposition. Magnetization and coercivity are not only influenced by the phase composition but also the microstructure. The fabrication processes and factors affecting the phase and microstructure are therefore covered. Finally, the productions of bulk MnAl magnets are addressed.

Effects of the Addition of Fe, Co on the Azo Dye Degradation Ability of Mn-Al Mechanically Alloyed Powders

Azo compounds are used in the textile and leather industry. A significant step during the azo dyes treatment of water is the degradation by breaking the N=N bonds. This break produces the decolorization of water. In this research work, 10% atomic of Fe or Co was added to produce ternary Mn-Al-rich, nanostructured, mechanically alloyed powders in order to improve the decolorization of Reactive Black 5 solutions and to check Fe and Co addition’s influence. The microstructure was followed by X-ray diffraction, the morphology and composition by electronic microscopy and energy-dispersive X-ray spectroscopy (EDS) microanalysis. The dye degradation was monitored with ultraviolet/visible absorption spectrophotometry. After degradation, the remaining organic compound was checked by high-performance liquid chromatography (HPLC) and the functional groups of the powdered alloys by infrared spectroscopy. Fe addition to Mn-Al displayed faster kinetics and a higher efficiency than the Co addition. The Mn-Al-Fe solution (0.25 g/100 mL) was fully decolorized in 5 min. On the other side, Mn-Al-Co powders were able to successfully decolorize the dyed solution in 10 min under the same conditions. Thus, nanocrystalline Fe-doped Mn-Al alloys are good candidates for use in the decolorization process, in comparison with Co-doped and other intermetallic particles.

Effect of the interaction between Fe and Si on the precipitation behavior of dispersoids in Al–Mn alloys during homogenization

The effects of different Fe and Si concentrations on the microstructure and precipitation behavior of dispersoids in Al–Mn alloys during homogenization were studied via optical microscopy (OM), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and electrical resistivity measurements. The equivalent diameter, size distribution, and number density of the dispersoids were measured. The evolution of dispersoids during homogenization was divided into four stages: nucleation, growth, dissolution, and coarsening. Si can strongly promote the precipitation of Mn from the matrix during homogenization. However, Fe can also promote the precipitation of Mn from the matrix during homogenization at high temperatures. This work proposes a new method to enhance the nucleation of dispersoids, which is helpful for further understanding the precipitation mechanism of the dispersoids.

Intensive processing optimization for achieving strong and ductile Al-Mn-Mg-Sc-Zr alloy produced by selective laser melting

The Sc-containing AlMn alloy system produced by additive manufacturing (AM) has recently presented exciting new opportunities to achieve a step-change in mechanical properties, but its processability remains unclear. In this work, the optimum processing window for the Al-Mn-Mg-Sc-Zr alloy fabricated by selective laser melting (SLM) has been established for the first time. The window covers the range of processing parameters that can lead to a good combination of part density, strength, ductility, and processability. The alloys fabricated within this optimized processing window of SLM have the material relative density more than 99.8% with less porosity. Moreover, all these alloys have the yield strength exceeding 430 MPa and the ductility of over 17%. Further microstructural examinations suggest that such excellent mechanical properties are associated with a bimodal grain architecture. Also, a high number density of intermetallic particles has been detected in these two-grain regions. They are confirmed to be Al3Sc and Mn(Fe)-rich quasicrystal. Most of these particles distributing along grain boundaries are expected to pin the grain boundaries and contribute to the high strength of this alloy. The findings will provide an essential basis for achieving exceptional mechanical performance and intricate geometry designs of the alloy using AM.

Nanodispersoids of the quasicrystalline I-phase in Mn- and Mg-bearing aluminum-based alloys

The current study compares Al-Mn and Al-Mn-Mg alloys’ precipitation behavior in a temperature range of 350–450 °C. Mn-bearing nanodispersoids of the quasicrystalline-structured I-phase precipitate during the decomposition of supersaturated Al-based solid solution in both alloys. In the binary Al-Mn alloy, quasicrystalline-structured dispersoids precipitate only in the grain boundaries. The Mg addition does not change the dispersoids’ composition but significantly accelerates the precipitation kinetics. The Mg addition provides the precipitation of high-density distributed I-phase nanodispersoids in the body of the grains. The annealing temperature increase results in the I-phase transformation to a cubic α-phase, with both phases coexisting in the alloy structure.

Physical Properties of Directionally Solidified Al-1.9Mn-5Fe Alloy

Al-1.9Mn-5Fe (wt.%) alloy was prepared by adding 5 wt.% Fe to the eutectic Al-Mn alloy. This alloy undergone controlled solidification under four different growth velocities (V) in Bridgman-type furnace. Eutectic spacings (λ), microhardness (HV), ultimate tensile strength (σU) and electrical resistivity (ρ) of these alloys were determined. While the HV and σU increased with increasing V values or decreasing λ, the elongation (δ) values decreased. In addition, relationships between these parameters were investigated using linear regression analysis. Microstructure photographs of directionally solidified samples were taken by optical microscope and scanning electron microscope (SEM). The eutectic spacings were measured from these photographs. The relationships among growth velocity (V), eutectic spacing (λ), microhardness (HV), ultimate tensile strength (σU) and electrical resistivity (ρ) were measured by suitable method and tests. The ρ measurements were carried out depending on V and temperature (T). While temperature coefficient of resistivity (αTCR) was calculated from the ρ–T curve, the values of thermal conductivity (K) predicted by Wiedemann–Franz (W–F) and Smith–Palmer (S–P) equations. It was found that the microstructure, microhardness, tensile strength and electrical resistivity were affected by both eutectic spacing and the growth velocity.

Experimental investigation to study the effects of processing parameters on developed novel AM(Al-Mn) series alloy

ABSTRACT In this paper, a novel AM series Mg alloy developed through a stir casting process has been discussed. The current research utilizes an improved stir casting setup with a systemized inert facility. The effects of the processing parameters viz. stirring speed and holding temperature on microstructure and mechanical properties of the novel AM alloy (Mg-7 wt%Al-0.9 wt%Mn) have been investigated during the study. In addition, the study also attempts to highlight the adverse effect of higher values of processing parameter on porosity. The five output variables, such as Ultimate tensile strength (UTS), Yield strength (YS), Elastic modulus (E), Hardness, and Density (d), were measured for different combinations of processing parameters. The results showed an evident rise in the mechanical properties with the variation of stirring speed and holding temperature; the optimum values were attained at 250 rpm and 700°C. A significant enhancement in the Elastic modulus (24.3%) and hardness (16.21%) was witnessed vis-à-vis the existing AM series alloy. The improved properties of the novel material will make it a prospective candidate for industrial applications.

Surface engineered AlMn alloy using laser surface alloying for wear resistance

Surface engineered AlMn alloy using laser surface alloying for wear resistance

Deformational and magnetic effects in Cu–Al–Mn alloys

A comparative analysis of the magnetic, size and deformation effects of martensitic transformation in aged Cu–Al–Mn alloys with a minimum width of the temperature hysteresis was performed. According to the experimental studies of the behavior of alloys during martensitic transformations, the changes in temperature dependences of thermal expansion, magnetic susceptibility and electrical resistance, depending on preliminary thermomagnetic treatment of alloys, were found. The thermomagnetic treatment contributes to a change in the magnitude of volume effect of martensitic transformation. Using magnetic analysis, the state and distribution of precipitated particles, affecting both the magnetic characteristics and the volume effects of martensitic transformation in the alloys, were determined.