Al Addition Research Articles

Mechanistic study of integrated CO2 capture and utilization over Cu and Al-modified calcined limestone with high stability using MFB-TGA-MS

This study explores the performance of dual-functional materials (DFMs) in cyclic integrated CO2 capture and reverse water–gas shift (ICCU-RWGS) reactions under fluidized, isothermal conditions. DFMs with a copper catalyst and alumina support on calcined natural limestone were analyzed using micro-fluidized bed thermogravimetric analysis coupled with mass spectrometry (MFB-TGA-MS). The results indicate that the 10 %Cu5%Al-CaO-IMP surpasses others, demonstrating a CO2 capture capacity of 10.67 mmol⋅g−1, 71.5 % in-situ CO2 conversion at 700 °C, and remarkable cyclic stability over 30 cycles. Cu and Al additions curtail CaO agglomeration during extended ICCU-RWGS and enhance CO2 and H2 activation by removing surface formate species, promoting CO production. Furthermore, non-catalytic gas–solid reactions coexist with catalytic gas–solid reactions, leading to gradual Cu particle coating by CaCO3 during carbonation. This phenomenon prevents Cu sintering but slightly reduces catalytic activity. These findings, combined with cost-effective materials (CaO, Cu, Al), hold significant promise for efficient and economically viable ICCU processes.

Effect of Al addition on Nb-rich phase precipitation behavior in ferritic stainless steel

The precipitation behavior of Nb-rich phase in Al-free and 1Al Nb-bearing ferritic stainless steels (FSSs) at 700 °C were investigated. The results show that Nb-bearing carbides and Laves phases with mutual transformation relationships are precipitated in both Al-free and 1Al Nb-bearing FSSs at the early stage of aging. At this stage, the coarsening rate of Laves phase is higher than that of Nb2C phase, and the addition of Al can promote the precipitation of Laves phase and weaken the precipitation of (Nb, Ti)2C phase. As the aging time extended to 60 min, the Nb-rich phase in the two experimental steels was mainly Laves phase, and the intragranular Laves phase showed feather like aggregation distribution. On the one hand, the added Al can be enriched in the Laves phase to produce a tailing morphology, on the other hand, it can reduce the diffusion rate of Nb atoms in the matrix, thereby weakening the aggregation state of the intragranular Laves phase. During the coarsening process of Laves phase, the addition of Al can reduce the coarsening rate of Laves phase by 7.45 times.

Achieving ultrahigh fatigue resistance of Al15(CoCrNi)85 medium-entropy alloy with deformable multicomponent BCC phases

The bending fatigue performance of the Al15(CoCrNi)85 medium-entropy alloy (MEA) with deformable multicomponent duplex BCC phases was investigated. The significantly enhanced fatigue resistance is attributed to the reduced cyclic strain localization, which originates essentially from the duplex BCC phases and the Al addition in the FCC matrix. Al addition in the FCC matrix might enhance the planar slip, which is beneficial for the reduction of the slip irreversibility of dislocations and the cyclic strain localization. The deformable duplex BCC phases with the semi-coherent interfaces efficiently coordinate the incompatible plastic deformation, which would help release the local stress concentration at the phase boundaries. By comparing to the widely used micro-electro-mechanical system (MEMS) material, the Al15(CoCrNi)85 MEA with superior fatigue performance might be accepted as a promising material for micromechanical parts in MEMS.

Effect of Mn and Al additions on the microstructure and hardness of a high Cr white cast iron for severe wear applications

Effect of Mn and Al additions on the microstructure and hardness of a high Cr white cast iron for severe wear applications

Effect of aluminium addition on the oxidation and carburization behaviour of austenitic stainless in high-temperature SCO2 environments

The AFA stainless steels with 2.5 and 5 wt% Al were developed, and Al addition had a great influence on intermetallic compounds in AFA alloys, especially resulting in increasing of B2-NiAl phase. After 3000 h exposure in SCO2, the thickness of oxide scales for two AFA alloys was 5–7 times thinner than that of ASS without Al, and the structure of formed oxide scale significant changed, i.e., from single Cr2O3 to double-layer with Fe/Cr oxide and Al oxide. As for AFA-2.5%, the formed Al-riched oxide inner layer was amorphous and unstable, resulting in the severe internal oxidation and carburization occurrence.

Effects of minor alloying elements (Si, Mn and Al) on the corrosion behavior of stainless steels in molten carbonate fuel cell cathode environment

Abstract Effects of minor alloying elements (Si, Mn, and Al) on the corrosion resistance behaviors of stainless steel (SS) modified 310S used as a cathode current collector (CCC) material for molten carbonate fuel cells (MCFC) were examined in a mixture of 62 mol% Li2CO3–38 mol% K2CO3 at 650 °C by measuring the change in corrosion potential and the potentio-dynamic, potentio-static polarization responses. The corrosion potential of modified 310S gradually increased after 9 h of immersion due to an active to passive transition and that of SSs added with minor alloying elements drastically increased before 6 h of immersion due to the reactive alloys. Si, Mn, and Al addition to base SS led to a decrease in corrosion resistance due to the rapid corrosion rate at the cathode operation potential, −40 mV, of the MCFC. The steady state current densities of SSs added with minor alloying elements were higher than that of 310S and modified 310S. Addition of Si, Mn, and Al induced a decrease in corrosion resistance of CCC materials in molten carbonate fuel cell operating temperatures, 650 °C.

Structural, optical, and dielectric properties of M/SnO2 (M= Al2O3, NiO, Mn3O4) nanocomposites

The structural parameters, optical properties, and dielectric constants at a frequency (f) range of 0.1–20 MHz, and temperature (T) range of 300–400 K of hydrothermally synthesized M/SnO2 nanocomposites (for simplicity M denotes oxides of Al, Ni, or Mn) were compared. Rietveld refined X-ray powder diffraction (XRD) analysis demonstrated the formation of hexagonal, cubic, or spinel crystal structures of Al2O3, NiO, or Mn3O4 phases, respectively, besides the tetragonal rutile crystal structure of SnO2. The impact of Al addition on the optical band gap of SnO2 is negligible while it decreased or increased by incorporation of Ni or Mn, respectively. The residual lattice dielectric constant of SnO2 was increased, while the real part of the dielectric constant and the ac conductivity of SnO2 were decreased by M incorporation. The dielectric parameters are remarkably affected by selected M, T, and f values and their changes agree with the Maxwell-Wagner model. The Q-factor of SnO2 was increased by M addition while decreased with increasing T. The Ni/SnO2 obeys the hole conduction at T ≤ 330 K, while Mn/SnO2 and Ni/SnO2 obey the electronic conduction at T > 330 K. The binding energy is independent of the chosen T for SnO2, whereas it sharply increases for Ni/SnO2 and slightly decreases for Al/SnO2 and Mn/SnO2. The F-factor of SnO2 was slightly decreased by M addition, but it was increased with T for SnO2, Al/SnO2, and Mn/SnO2 while was decreased for Ni/SnO2. The Cole-Cole plots for M/SnO2 composites were analyzed, and the components of the equivalent circuit were determined. The electrical impedance, resistance of grains, resistance of grain boundaries, and equivalent resistance of SnO2 were increased by M incorporation, whereas equivalent capacitance was decreased. The findings recommend the SnO2-based nanocomposites for applications in optoelectronics, lithium batteries, supercapacitors, and solar cell devices.

Increasing ductility via Cu addition in AlxCrFeMnNi: Towards a scrap-based high entropy alloy

Alloys comprising common alloying elements are more amenable to accepting high fractions of scrap. The present study examines the effect of Cu and Al addition on common element containing multiple principal element alloy (CE-MPEA): AlxCuyCrFeMnNi (x = 0, 0.15, 0.3, 0.6, 0.9 and y = 0, 0.07, 0 = 0.14). Alloys were fabricated by arc casting. As expected, after quenching, the microstructures displayed FCC A1, Cr-rich BCC A2 and B2 precipitate phases in varying amounts. Adding small amounts of Cu to low and medium Al alloy groups increased the FCC phase fraction and refined the FCC grains. It is proposed that these microstructural changes account for the increased ductility seen to accompany Cu addition. A hybrid model was successfully employed to predict the hardness of the FCC phase. In contrast to high Cu-containing HEAs from prior studies, Cu additions in the studied alloys did not detrimentally affect the corrosion resistance in idealised polarization corrosion tests in salt solution. This can be ascribed to the absence of a Cu-rich FCC phase at the low Cu levels employed in the present work. The current alloys show promise as a base composition for further development into a tough fine-grained stainless alloy able to be produced using high fractions of scrap input.

Site-occupation and structure relaxation behavior of C14-type stoichiometric and iron-rich Fe2Nb Laves phases with addition of aluminum or chromium

Powder X-ray diffraction Rietveld refinement for Al- or Cr-added stoichiometric and Fe-rich off-stoichiometric C14-type Fe2Nb Laves phases were examined to elucidate the site-occupation behavior of Al and Cr, and the resulting changes in the lattice parameters and the c/a axial ratio in the Fe2Nb Laves phases. In the case of the stoichiometric composition of the Fe2Nb Laves phase, no anti-site atoms were presented at the Fe and Nb both sites Al or Cr addition to the Fe-33.3at%Nb Laves phase by replacing Fe with Al or Cr did not generate anti-site Fe atoms, and Al and Cr preferentially occupied the Fe sites. Al and Cr atoms can replace Fe atoms at both the 6 h and 2a Fe sites in the case of Fe-rich alloy, and they also can occupy the Nb site (4f) by replacing anti-site Fe atoms. However, Al and Cr had no preferential occupation of any of these sites. The accuracy of Rietveld refinement was confirmed by observation through high-angle annular dark-field scanning transmission electron microscopy. The lattice parameters of the a and c axes increased almost linearly with increasing the added Al or Cr concentrations, but the c/a ratio showed different behavior. Therefore, the change in c/a cannot be explained solely in terms of the concentration of the added element; however, it is proposed that the change in c/a is interpreted by using parameters consistent with site-occupancy values.

Effects of Al additions on precipitation, recrystallization and mechanical properties of hot-rolled ultra-super ferritic stainless steels

In this study, 1.0 wt%Al element was added into the traditional 26.8Cr-3.7Mo–2Ni super-ferritic stainless steel to tailor the brittle phase precipitation, recrystallization microstructure and mechanical property via solution annealing at temperatures of 950–1150 °C. The experimental results demonstrated that hot-rolled microstructure for 1.0Al sample consisted of surface fine grain region and core elongated grains together with TiN, NbC and Laves phase, while none of these fine grains appeared in 0Al samples. After annealing below 1050 °C, both σ-phase and Laves phase were formed in Al-free samples, while only abundant Laves phase precipitated in 1.0Al sample indicating the inhibition effect of Al on the σ-phase and the promotion effect on Laves phase. When annealing above 1050 °C, recrystallization was completed and neither σ-phase nor Laves phase were observed. Relatively stable mean grain size was produced due to the Laves phase pinning effect during annealing at 1050 °C, while the Nb/Al solute drag effect bore responsibility for the situation at 1050–1150 °C. Sudden grain coarsening phenomenon appeared after annealing above 1150 °C. Al additions gave a solution strengthening and intensive Laves phase precipitation strengthening for the designed alloys, and good comprehensive mechanical properties were obtained demonstrating the probability of developing of the Al-modified ultra-super stainless steels.

The effect of Al addition on the microstructure, magnetostrictive and mechanical properties of Fe73Ga27 alloy

Fe-Ga alloy exhibits two magnetostrictive peaks when the Ga content (at%) is 19 and 27, respectively but most studies have focused on improving the performance of Fe81Ga19. In order to reduce the manufacturing cost of the alloys and achieve better mechanical properties, Al element is used to replace part of the Ga of Fe73Ga27 alloy in this experiment. So long as the magnetostrictive properties does not decrease significantly, which is in line with expectations from an engineering application perspective. Fe73Ga27−xAlx (x = 0,1,2,3,4,5) alloys were prepared by vacuum arc furnace and the effect of Al addition on the microstructure, magnetostrictive properties, and mechanical properties of the alloys is studied. The results show that the phase structure of alloys is chiefly composed of A2 phase and the metallographic structure of the alloys is comprised of equiaxed and columnar grains. The fracture morphology of the alloys is principally intergranular brittle fracture and cleavage fracture, and the reasons for the alloys fracture include the detachment of Fe and Al elements and the segregation of Fe, Ga, Al elements. Except for Fe73Ga27 alloy, the tensile strength, elongation, and Vickers hardness of the alloys are ameliorated when the content of Al added is equal to 4 at% while the parallel magnetostrictive strain(λ∥) of the alloy crested 81 ppm, which is 24.3% higher than Fe73Ga27.

Improved corrosion resistance of laser melting deposited CoCrFeNi-series high-entropy alloys by Al addition

The microstructural evolution, pitting performance, and passive-film properties of AlxCoCrFeNi high-entropy alloys (HEAs) fabricated via laser melting deposition (LMD) were investigated using material characterization techniques and electrochemical measurements. The substrates of the LMD HEAs transform from a face-centred cubic (FCC) to a body-centred cubic (BCC) structure with increasing Al addition. The BCC-structured B2 and A2 phases precipitate in the HEA substrate when the Al content reaches 10 mol.%. Ternary-phase HEA with Al addition of 10 mol.% exhibits the best corrosion resistance, which is attributed to favourable modifications in the Cr2O3 content and passive-film thickness.

Cooperative regulation of mechanical properties and magnetoresistance effect in high-entropy alloys by spinodal decomposition

Adjusting the phase composition of high-entropy alloys is an effective approach to change its mechanical and magnetic properties. In this study, FeCoNiCr high-entropy alloys with Al addition (AlxFeCoNiCr; x = 0.0, 0.25, 0.5, 0.75, 1.0, 1.25, 1.75) were prepared by argon arc melting to obtain a special spinodal decomposition structure. There precipitated body-centered cubic (BCC) phase in the face-centered cubic (FCC) phase matrix for the samples with Al (x = 0.25, 0.5, 0.75) addition. Furthermore, the increase in the Al content (x = 1.0, 1.25, 1.75) transformed the alloy into a BCC phase, and resulted in a spinodal decomposition in the alloy. This spinodal decomposition created a low-misfit coherent nanostructure combining the enriching AlNiCo ordered B2 matrix with enriching Fe–Cr BCC disordered nanoprecipitates. The difference in the distribution of chemical elements of the two phases leads to different magnetic properties and induces the magnetoresistance (MR) effect. This provides a pathway for the design of advanced functional high-entropy alloys.

Effect of Aluminum Addition on the Microstructure, Magnetic, and Mechanical Properties of FeCrCoNiMn High-Entropy Alloy

High-entropy FeCoCrNiMn (C1) and FeCoCrNiMn10Al10 (C2) alloys (HEAs) were mechanically alloyed for 24 h and heated to 900 °C (C1_900 °C and C2_900 °C). The powders were also compacted into pellets (C1_pellet and C2_pellet) and sintered at 500 °C for 1 h. Crystal structure, microstructure, magnetic, and mechanical properties were investigated by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, and microindentation. During the milling process, a mixture of body-centered-cubic (BCC) and face-centered-cubic (FCC) phases with a crystallite size in the range of 9–13 nm was formed in the C1 HEA alloy. The dual FCC + BCC solid solutions remain for the C1_pellet and transform to a single FCC for the C1_900 °C powders. Al addition stabilizes the BCC structure in the FeCoCrNiMn10Al10 HEA alloy, as revealed by the structural refinement. The structure exhibits a mixture of BCC + FCC solid solutions for the C2 powders and BCC + FCC + CrCo sigma phase for the C2_pellet and C2_900 °C powders. The crystallite sizes are in the range of 6-93 nm for all the samples. The saturation magnetization (Ms), coercivity (Hc), and squareness ratio (Mr/Ms) are estimated to be 24.2 emu/g, 153.62 Oe, and 0.165, respectively, for C1 and 28.45 emu/g, 188.48 Oe, and 0.172 for C2. The C1_900 °C and C2_900 °C powders exhibit, respectively, paramagnetic and soft magnetic behaviors and an exchange bias at room temperature. The C1_pellet and C2_pellet HEAs show high hardness values of 584.85 Hv and 522.52 Hv, respectively.

Effect of Al addition on microstructure and wetting properties of quinary lead-free solder alloy systems

In this study, the wetting and microstructural properties of SACBi-xAl (x = 0.05, 0.1, 0.3, 0.5, and 0.6%) quinary lead-free solder alloys produced by adding various amounts of Al to the quaternary SAC-1Bi lead-free solder alloy (wt%) were investigated. The wetting and microstructural properties of Al-added quinary lead-free solder alloys on Cu substrate in an Ar gas atmosphere were investigated. It was reported that the best wetting angle (38.44° for the 325 °C temperature value) and melting temperature (212.5 °C) belonged to the SACBi-0.1Al solder alloy. When the microstructural properties are examined, it is seen with the help of SEM images that the CuAl IMC phase, which is rich in Al, has replaced Cu6Sn5 and Ag3Sn IMCs.

Enhancing yield strength and ductility of Fe-Mn-C-xAl (x = 0, 3) high manganese steel by cryogenic rolling

In this study, cryogenic rolling was employed to introduce nanotwins into Fe-Mn-C-xAl (x = 0, 3) high manganese steel in order to enhance its yield strength. The yield strength of 0Al and 3Al steels were improved after cryogenic rolling, and the yield strength reached 1079 MPa and 961 MPa, respectively. Furthermore, excellent ductility was achieved after tempering without any reduction in strength, and the ductility of 0Al and 3Al steels were 23.6 % and 14.9 %, respectively. The effect of Al addition on the mechanical properties was investigated and the strengthening contribution mechanism is discussed.

Powder plasma arc additive manufacturing of (AlTi)2x(CoCrNi)100–2x medium-entropy alloys: Microstructure evolution and mechanical properties

In this work the effects of Al and Ti element addition on the microstructure and mechanical properties of CoCrNi medium-entropy alloys (MEAs) has been investigated. A novel (AlTi)2x(CoCrNi)100–2x MEAs was fabricated by using powder plasma arc additive manufacturing technique. The influences of Al and Ti elements on the microstructure, mechanical properties and strengthening mechanisms were analyzed by XRD, EBSD and TEM. The (AlTi)2x(CoCrNi)100–2x MEAs exhibited columnar crystal structure, but the average grain size and texture decreased continuously with increasing values of x. Moreover, tensile test results showed that (CoCrNi)90Al5Ti5 alloy possessed strength-ductility balance (yield strength, ultimate tensile strength and elongation to failure of 664 MPa, 897 MPa and 19.3 %, respectively). The analysis on the strengthening mechanism showed that the solid solution strengthening effect was more dominant with increasing of the x in all alloys. (CoCrNi)94Al3Ti3 and (CoCrNi)90Al5Ti5 have similar average grain sizes, wherein the difference in mechanical properties between both the alloys can be mainly attributed to the formation of fine grain sizes. (CoCrNi)90Al5Ti5 has a small amount of dislocations, solid solution strengthening and grain boundary strengthening are the main sources of the excellent properties.

Development of advanced cementite-free bainitic steel using Ni, Al and Cu additions – Design concept and phase transformations study

A novel concept, consisting of the stabilization of retained austenite with Ni, Al, and Cu additions instead of using Si as the major alloying element to prevent carbide formation, is proposed to design nanocrystalline, cementite-free bainitic steels. In this work, the novel steel (wt.%) Fe-0.40C-0.50Mn-8.0Ni-2.65Al-0.8Cu was designed. Dilatometry investigations were performed to obtain the experimental CCT and TTT diagrams for this material. It was concluded that the bainitic reaction occurs between 400 and 225 °C during a transformation time ranging from 2 h to 66.5 h, respectively. An in-depth analysis performed on the resulting materials confirmed the presence of an ultrafine structure free of cementite consisting of carbon supersaturated laths of tetragonal bainitic ferrite and retained austenite with thin film and block morphologies. The use of Ni, Al and Cu as alloying elements leads to high carbon content in both populations of retained austenite, which prevents, the formation of fresh martensite during cooling to room temperature. The results of this research constitute a novel insight into the design of ultra-fine, cementite-free bainitic steels.

Effect of Al Content on Microstructure, Mechanical, and Corrosion Properties of (Fe33Cr36Ni15Co15Ti1)100−xAlx High‐Entropy Alloys

(Fe33Cr36Ni15Co15Ti1)100−xAlx (x = 0, 3, 5, 6, 7, 8) high‐entropy alloys (HEAs) are prepared by arc melting. The influence of Al element addition on the microstructure, mechanical properties, and anticorrosion in 3.5 wt% NaCl aqueous solution is systematically investigated. The microstructure analysis indicates that HEAs possess varying phases from face center cubic/face‐centered cubic (FCC) + sigma to FCC + body‐centered cubic (BCC) and then FCC + BCC +sigma, the last to BCC + sigma with the increase of Al content. The compressive results suggest that the Al addition exhibits a significant elevation in strength. Particularly, Al7 alloy shows a superior strength and plasticity, which presents a yield strength of 1315.3 MPa and a compressive strain over 50%. Order strengthening and coherent strengthening of nanosized phase are regarded as main strengthening effects. In addition, Al element is harmful for the corrosion resistance of (Fe33Cr36Ni15Co15Ti1)100−xAlx HEAs system, which is ascribed to the weakened passive film stability. It is also noted that pits tend to be initiated in relatively Cr‐depleted phases (FCC or B2 phase) due to the inhomogeneous elemental distribution‐induced galvanic corrosion. In spite of this, all HEAs exhibit superior corrosion resistance than that of 304SS.

Effect of Al addition and rolling reduction on microstructure and texture evolution of Mg–3Sn alloy during high-speed rolling

Effect of Al addition and rolling reduction on microstructure and texture evolution of Mg–3Sn alloy during high-speed rolling