Solid Solution Content Research Articles

The effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated Ti–6Al–4V alloys

Laser powder bed fusion (LPBF) excels at creating intricately shaped parts, which will result in variations in solidification conditions, microstructure formation and mechanical properties. To address this issue, three distinct shapes: cubic, pyramidal and inversed pyramidal Ti–6Al–4V alloy specimens were fabricated using LPBF technology. The effects of specimen geometry on microstructure formation, transformation as well as its effects on mechanical properties were investigated in the present study. Our results show that specimen geometry significantly affects the thermal gradient, influencing nucleation and growth during fabrication. EBSD (Electron Backscatter Diffraction) characterization reveals that the primary β-phase grows in columnar grains in cubic specimens, coarse columnar grains along lateral faces in pyramidal specimens, and nearly equiaxed grains in inverted pyramidal specimens, leading to a significant reduction in texture. Nanoindentation tests show higher nanohardness in the top parts of cubic and pyramidal specimens compared to the bottom parts, while inverted pyramidal specimens have consistent nanohardness throughout. This variation is due to differences in solid solute concentration, melt pool undercooling, and thermal histories during and post solidification processes respectively. TEM results indicate that the fine lath phase on the top parts has transformed into β-phase, while the bottom parts remain as α′ phase, highlighting a disparity due to different thermal cycling times and temperatures.

Phase evolution mechanism of SiC-Al-Si composite under flowing nitrogen at 1600 °C

Resin-bonded SiC-Al-Si composite was prepared and sintered under flowing nitrogen at 1600℃. By adjusting the Al/Si ratio, the controllable synthesis of various non-oxide reinforcing phases was achieved. The phase evolution mechanism was revealed, providing a theoretical foundation for the production and application of novel SiC-based refractory. As flowing nitrogen contained traces of oxygen, both Al and Si in the surface layer of the samples may be oxidized and nitrided. As the Al/Si mass ratio increased, the phase evolution in the surface layer of sintered samples followed this sequence: Si5AlON7→Si3Al3O3N5+AlN-SiC solid solution→AlN-SiC solid solution +Al2O3→Al7O3N5+Al2O3. As Al and Si consumed oxygen and generated non-oxides with multi-morphic sealed pores in the surface layer, the inner layer remained oxygen-free and low-nitrogen, leading to different phase evolution. As the Al/Si mass ratio increased, the phase evolution in the inner layer followed: Si3N4→AlN-SiC solid solution→AlN-SiC solid solution (content increase)→Al4SiC4. The synergistic toughening of various non-oxide resulted in a cold crushing strength of sintered samples exceeding 150 MPa. A reaction model was established.

Combustion synthesis of the (Ti,Zr)B2-(Zr,Ti)C eutectic composites: Structure formation and properties

The macrokinetic characteristics of combustion of the quaternary Ti-Zr-B-C mixture as well as the mechanism and stages of phase formation for the synthesis products were investigated. The mechanical and thermophysical properties of the hot-pressed boride/carbide ceramics with eutectic composition (Ti,Zr)B2-43%at.(Zr,Ti)C were measured. Preliminary mechanical alloying (MA) of the (Zr + Ti) mixture was shown to yield Ti/Zr granules having a laminar structure and consisting of alternating layers of titanium, zirconium, and (Zr,Ti)ss solid solution. The method used to prepare reaction mixtures and the initial temperature T0 increased within the range of 20–370 °C have virtually no effect on combustion temperature, which is 2260–2400 °C, while higher T0 increases the combustion rate by a factor of 1.5–2. The use of MA Ti/Zr granules reduces the combustion rate as well as the specific heat release amount and the heat release rate. Time-resolved X-ray diffraction data showed that binary carbides (Zr1-xTix)C and diborides (Ti1-yZry)B2 of variable stoichiometry are formed in the combustion wave of the Ti-Zr-B-C reaction mixtures within less than 0.25 s. The carbide and diboride phases are formed simultaneously; the use of MA Ti/Zr granules in the reaction mixtures reduces the content of solid solutions of variable stoichiometry among the reaction products. The ceramics fabricated using a combination of combustion synthesis and hot pressing have a dense and homogeneous structure that consist of bonded grains of the diboride (Ti0.80Zr0.20)B2 and carbide (Zr0.83Ti0.17)C phases having the following properties: density, 5.3 g/cm3; hardness, 22.9 GPa; fracture toughness, 4.7 MPa m0.5; heat capacity, 0.52 J/(g·K); thermal diffusivity, 11.67 mm2/s; and thermal conductivity, 33.28 W/(m·K).

First Principles Calculation of the Effect of Cu Doping on the Mechanical and Thermodynamic Properties of Au-2.0Ni Solder.

To meet the demands for high-temperature performance and lightweight materials in aerospace engineering, the Au-Ni solder is often utilized for joining dissimilar materials, such as Ti3Al-based alloys and Ni-based high-temperature alloys. However, the interaction between Ti and Ni can lead to the formation of brittle phases, like Ti2Ni, TiNi, and TiNi3, which diminish the mechanical properties of the joint and increase the risk of crack formation during the welding process. Cu doping has been shown to enhance the mechanical properties and high-temperature stability of the Au-Ni brazed joint's central area. Due to the difficulty in accurately controlling the solid solution content of Cu in the Au-Ni alloy, along with the high cost of Au, traditional experimental trial-and-error methods are insufficient for the development of Au-based solders. In this study, first principles calculations based on density functional theory were employed to analyze the effect of Cu content on the stability of the Au-2.0Ni-xCu (x = 0, 0.25, 0.5, 0.75, 1.0, 1.25 wt%) alloy phase structure. The thermal properties of the alloy were determined using Gibbs software fitting. The results indicate that the Au-2.0Ni-0.25Cu alloy exhibits the highest plastic toughness (B/G = 5.601, ν = 0.416, Cauchy pressure = 73.676 GPa) and a hardness of 1.17 GPa, which is 80% higher than that of Au-2.0Ni. This alloy balances excellent strength and plastic toughness, meeting the mechanical performance requirements of brazed joints. The constant pressure specific heat capacity (Cp) of the Au-2.0Ni-xCu alloy is higher than that of Au-2.0Ni and increases with Cu content. At 1000 K, the Cp of the Au-2.0Ni-0.25Cu alloy is 35.606 J·mol-1·K-1, which is 5.88% higher than that of Au-2.0Ni. The higher Cp contributes to enhanced high-temperature stability. Moreover, the linear expansion coefficient (CTE) of the Au-2.0Ni-0.25Cu alloy at 1000 K is 8.76 × 10-5·K-1, only 0.68% higher than Au-2.0Ni. The lower CTE helps to reduce the risk of solder damage caused by thermal stress. Therefore, the Au-2.0Ni-0.25Cu alloy is more suitable for brazing applications in high-temperature environments due to its excellent mechanical properties and thermal stability. This study provides a theoretical basis for the performance optimization and engineering application of the Au-2.0Ni-xCu alloy as a gold-based solder.

Microstructure and ablation behavior of Zr-based ultra-high-temperature gradient composites

To obtain high-performance Zr-based ultra-high-temperature composites, Zr-based ultra-high-temperature gradient composites were prepared by changing the laying method of the infiltrant via reactive melt infiltration. The effects of different infiltrant laying methods on the microstructure and ablative properties of Zr-based ultrahigh-temperature gradient composites were investigated. The results showed that the gradient structure of the Zr-based ultrahigh-temperature gradient composites differed when the composition ratio of the infiltrant was changed. When the thicknesses of the Zr/Mo/Si layers were 6/4/12 mm and 8/2/12 mm, the SiMoZrC solid solution content in the samples increased and decreased along the infiltration direction, respectively. The gradient samples were ablated in an oxyacetylene flame at 3000 °C for 40 s. The ablation resistance of the sample was the highest when the infiltrant was a powder and the thickness of the Zr/Mo/Si layer was 6/4/12 mm.

Spectral-luminescence characteristics of solid solutions ZrO2-Eu2O3 crystals

Data on the structure of (100-x) mol.% ZrO2 - х mol.% Eu2O3 solid solution concentration series (x = 4, 6, 8, 10, 12, 15, 20, 27) have been presented. The crystals with x = 4 have a hexagonal structure, while those with x = 8 are a mixture of cubic and tetragonal phases. The crystals with x = 10, 12 and 15 have a cubic structure, and those with x = 27 are two-phase and contain cubic modification and pyrochlore phase.Luminescent spectra of the (100-x) mol.% ZrO2 - х mol.% Eu2O3 solid solutions have been taken in the as-grown and air-annealed states. The presence of Eu2+ ions was revealed in (100-x) mol.% ZrO2 - х mol.% Eu2O3 solid solution concentration series (x = 4, 6, 8, 10, 12, 15, 20, 27) after growth, the content of which decreases significantly after heat treatment in air. It has been shown that in (96-85) mol.% ZrO2 - (4–15) mol.% Eu2O3 crystals the relative proportion of optical centers of Eu3+ surrounded by oxygen seven-vertex is lower compared to crystals (96.7–85) mol.% ZrO2 - (3.6–15) mol.% Gd2O3 - 0.1 mol.% Eu2O3. The (73, 80) mol.% ZrO2 - (20, 27) mol.% Eu2O3 crystals contain optical centers of Eu3+ surrounded by oxygen six-vertex with two oxygen vacancies along the diagonal faces of the cubic crystal lattice. Their percentage being higher than in the (79.9, 76.9) mol.% ZrO2 - (20, 33) mol.% Gd2O3 - 0.1 mol.% Eu2O3 crystals.In crystals of (100-x) mol.% ZrO2 - х mol.% Eu2O3 solid solution concentration series (x = 4, 6, 8, 10, 12, 15, 20, 27), the presence of concentration quenching was revealed with increasing concentration of europium ions.

The Effects of Different Zn Forms on Sintering Basic Characteristics of Iron Ore.

The micro-sintering method was used to determine the sintering basic characteristics of iron ore with Zn contents from 0 to 4%, the influence mechanism of Zn on sintering basic characteristics of iron ore was clarified by means of thermodynamic analysis and first-principles calculations. The results showed that (1) increasing the ZnO and ZnFe2O4 content increased the lowest assimilation temperature (LAT) but decreased the index of liquid phase fluidity (ILF) of iron ore. The addition of ZnS had no obvious effect on LAT but increased the LIF of iron ore. (2) ZnO and ZnFe2O4 reacted with Fe2O3 and CaO, respectively, during sintering, which inhibited the formation of silico-ferrite of calcium and aluminum (SFCA). The addition of ZnS accelerated the decomposition of Fe2O3 in the N2 atmosphere; however, the high decomposition temperature limited the oxidation of ZnS, so the presence of ZnS had a slight inhibitory effect on the formation of SFCA. (3) The Zn concentrated in hematite or silicate and less distributed in SFCA and magnetite in the form of solid solution; meanwhile, the microhardness of the mineral phase decreased with the increase in Zn-containing solid solution content. As the adsorption of Zn on the SFCA crystal surface was more stable, the microhardness of SFCA decreased more. The decrease in microhardness and content of the SFCA bonding phase resulted in a decrease in the compressive strength of the sinter.

Large electrostrain achieved in BNKT‐based ceramics by the adjustment of phase boundary with Ba(Sn0.70Nb0.24)O3 addition

AbstractIn the current study, the incorporation of Ba(Sn0.70Nb0.24)O3 (BSN) effectively modifies the phase boundary of the 0.8(Bi0.50Na0.50)TiO3‐0.2(Bi0.50K0.50)TiO3 (BNKT) lead‐free ceramic material, inducing enhanced electrostrain properties at room temperature, particularly results in a “bud‐like” strain profile without negative strain. A comprehensive investigation has been conducted into the microstructure, electrical properties, and electrostrain properties of the above‐mentioned ceramics. The addition of BSN was observed to be well incorporated into the BNKT crystal structure, forming a single perovskite structure according to the X‐ray diffraction pattern. With the increase in BSN solid solution content, the temperature at which the transition from ferroelectric to the relaxor phase occurs shifted from 88.1°C to beneath room temperature (30°C). Specifically, the BNKT‐0.0075BSN ceramic demonstrated a positive strain response of 0.459% along with a large signal piezoelectric coefficient (d33*) of 643 pm/V. Additionally, the strain hysteresis of the BNKT‐0.0175BSN ceramics was only about 3% at 120°C. These experimental findings suggest that BNKT‐xBSN ceramics could be strong contenders for actuators and sensors, presenting promising opportunities for lead‐free ceramic actuator applications.

High-quality Cr2O3 - Ga2O3 solid solutions films grown by mist-CVD epitaxy

Micron-thick layers of (Cr1-xGax)2O3 solid solutions were grown by modified mist chemical vapor deposition (mist-CVD) with three different Ga concentrations. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods were used to analyze the quality of the films. They showed good crystallinity, homogeneity and coalescence of the samples. Solid solution contents estimation was performed via applying Vegard’s law to XRD data and by its results the highest reached Cr:Ga ratio is approximately 1:1. Transmission spectra of solid solutions demonstrated blue-shift of the absorption edge with increase of the Ga contents. Optical bandgap increased from 3.06 eV for undoped Cr2O3 sample to 3.73 eV for the layer with the highest Ga concentration.

Microstructure, hardness, and tribological performance of D2 tool steel fabricated by laser cladding using pulsed wave and substrate heating

D2 steel is a tool grade steel that presents hot cracking problems during the solidification process due to its alloying elements. On the other hand, additive manufacturing processes have great potential to manufacture, repair, and functionalize metal parts due to their low heat input, minimal distortion, and excellent metallurgical bonding. In this work, D2 metallic powder was deposited by the laser cladding process using pulsed wave, without and with preheating of the substrate. Through ANOVA statistical analysis using a complete factorial design 24, the optimal regions were determined to obtain D2 deposits with minimum dilution and depth, and maximum widths, heights and high hardness. Once the optimal parameters of the process were established, the coatings were deposited without and with preheating the substrate where, regardless of the condition, coatings without defects and good metallurgical adhesion were obtained. Coatings with preheating obtained higher cooling rates, where lower laser powers promoted higher rates; while in the coatings without preheating, lower duty functions promoted higher rates. The austenite, martensite and M7C3 eutectic carbides phases were obtained, with austenite being the main phase due to the C content in solid solution due to the cooling rates achieved. The coatings in as-built condition, reached hardness values between 606 and 711 HV (55–60 HRC), where the preheated coatings obtained the highest values. On the contrary, the coatings without preheating showed a better wear resistance (7.672 x10-6 mm3/Nm) due to the formation of tribo-layers due to the formation of oxides due to the higher amount of austenite.

Enhancing the strength of the PCBN/M42 joint via a solid solution brazed seam design involving a pre-melted CuNi layer and a Ti interlayer

We present a two-step method to achieve high-strength PCBN-M42 joints by employing a pre-melted CuNi layer combined with a Ti interlayer. Reliable interface bonding with PCBN is established through the Cu-Ni-Ti eutectic reaction while effectively retaining a considerable solid solution content within the joint, thus significantly enhancing the joint strength.

The Effect P Additive on the CeZrAl Support Properties and the Activity of the Pd Catalysts in Propane Oxidation.

The properties of a catalyst support are closely related to the catalyst activity, yet the focus is often placed on the active species, with little attention given to the support properties. In this work, we specifically investigated the changes in support properties after the addition of P, as well as their impact on catalyst activity when used for catalyst preparation. We prepared the CeO2-ZrO2-P2O5-Al2O3 (CeZrPAl) composite oxides using the sol-gel, impregnation, and mechanical mixing methods, and characterized the support properties using techniques such as XRD, XPS, SEM-EDS, N2 adsorption-desorption, and Raman spectra. The results showed that the support prepared using the sol-gel method can exhibit a more stable phase structure, larger surface area, higher adsorption capacity for oxygen species, and greater oxygen storage capacity. The addition of an appropriate amount of P is necessary. On the one hand, the crystallization and growth of CePO4 can lead to a decrease in the Ce content in the cubic phase ceria-zirconia solid solution, resulting in a phase separation of the ceria-zirconia solid solution. On the other hand, CePO4 can lock some of the Ce3+/Ce4+ redox pairs, leading to a reduction in the adsorption of oxygen species and a decrease in the oxygen storage capacity of the CeZrPAl composite oxides. The research results indicated that the optimal P addition is 6 wt.% in the support. Therefore, we prepared a Pd/CeZrPAl catalyst using CeZrAl with 6 wt.% P2O5 as the support and conducted the catalytic oxidation of C3H8. Compared with the support without P added, the catalyst activity of the support loaded with P was significantly improved. The fresh and aged (1000 °C/5 h) catalysts decreased by 20 °C and 5 °C in T50 (C3H8 conversion temperature of 50%), and by 81 °C and 15 °C in T90 (C3H8 conversion temperature of 90%), respectively.

Advanced Cd1-xMnxTe:Fe2+ semiconductor crystals for IR applications: The role of the composition and sin-band redshift spectra effect

Doped semiconductor crystals of solid solution Cd1-xMnxTe:Fe2+ were grown by the high-pressure Bridgman method, covering the range of their existence as a zinc blende structure (0 < x < 0.76). The concentration of the Fe2+ impurities was approximately 10−3 wt% in all the studied samples. The structural and optical properties of the crystals were investigated, including the case of high concentrations of x > 0.4. The correlations between the composition of solid solution crystals of Cd1-xMnxTe:Fe2+, the lattice constant, the band gap, and the maxima positions of the Fe2+ active ion absorption and emission spectra were found experimentally and explained physically. A theoretical model based on the principle of compositional additivity for solid solution semiconductor materials was first used for explaining the long-wavelength sin-band linear “redshift” of absorption and emission bands in the spectra of Cd1-xMnxTe:Fe2+ crystals with increasing solid solution concentration. A new effect is discovered for the differentiated redshift of the Jahn-Teller components (bands) of the total absorption spectrum. Longwavelength absorption bands have a stronger redshift than shortwavelength absorption bands. The redshifts in the maxima of the total absorption and emission spectra have shift (slope) coefficients Kab≈1.7 nm/at.% and Kem≈6.1 nm/at.%, respectively. The obtained results can be used to predict and design laser media based on Cd1-xMnxTe:Fe2+ solid solution crystals while controlling the lasing range (for all Mn concentrations).

Thermodynamic modelling application for prediction of diffusion formation of supersaturation solution

Abstract In this paper the effect of diffusion formation of supersaturated solid solution in the Al–Ge system is discussed. It was shown that at relatively low temperatures of diffusion annealing, Ge concentration in Al-based solid solution became higher than the solubility limit at given temperatures. The maximal concentration of Ge was determined by extrapolation of the diffusion profile on the Ge/Al interface. Analysis of diffusivity of Al in Ge allowed to suggest that slow diffusion in Ge restricts the formation of Ge-based solid solution. Qualitative approach confirmed this suggestion.

Microstructure of Al-2%Si and Al-6%Si Strips Cast Using Vertical-Type High-Speed Twin-Roll Caster

Al-2%Si and Al-6%Si were cast at a roll speed of 30 m/min and a roll load of 5 N/mm using a vertical-type high-speed twin-roll caster. The rolls were suddenly stopped during casting and the molten metal was solidified. The effect of Si content on the microstructure at the cross section near the roll bite was investigated using Weck’s reagent. The cross section of the Al-2%Si strip consisted of five layers (one center layer, two middle layers, and two surface layers) at the roll bite and that of the Al-6%Si strip consisted of three layers (one center layer and two side layers). The a-Al in the center layer was globular for both Al-2%Si and Al-6%Si. The relative thickness of the center layer for Al-6%Si was greater than that for Al-2%Si. In Al-2%Si, the surface layer had a very fine chill-zone microstructure. The Si solid-solution content in the α-Al in the surface layers and the center layer was less than that in the middle layers in the Al-2%Si strip.

Enhancing the Resistive Memory Window through Band Gap Tuning in Solid Solution (Cr1-xVx)2O3.

Memories based on the insulator-to-metal transition in correlated insulators are promising to overcome the limitations of alternative nonvolatile memory technologies. However, associated performances have been demonstrated so far only on narrow-gap compounds, such as (V0.95Cr0.05)2O3, exhibiting a tight memory window. In the present study, V-substituted Cr2O3 compounds (Cr1-xVx)2O3 have been synthesized and widely investigated in thin films, single crystals, and polycrystalline powders, for the whole range of chemical composition (0 < x < 1). Physicochemical, structural, and optical properties of the annealed magnetron-sputtered thin films are in very good agreement with those of polycrystalline powders. Indeed, all compounds exhibit the same crystalline structure with a cell parameter evolution consistent with a solid solution over the whole range of x values, as demonstrated by X-ray diffraction and Raman scattering. Moreover, the optical band gap of V-substituted Cr2O3 compounds decreases from 3 eV for Cr2O3 to 0 eV for V2O3. In the same way, resistivity is decreased by almost 5 orders of magnitude as the V content x is varying from 0 to 1, similarly in thin films and single crystals. Finally, a reversible resistive switching has been observed for thin films of three selected V contents (x = 0.30, 0.70, and 0.95). Resistive switching performed on MIM devices based on a 50 nm thick (Cr0.30V0.70)2O3 thin film shows a high endurance of 1000 resistive switching cycles and a memory window ROFF/RON higher by 3 orders of magnitude, as compared to (Cr0.05V0.95)2O3. This comprehensive study demonstrates that a large range of memory windows can be reached by tuning the band gap while varying the V content in the (Cr1-xVx)2O3 solid solution. It thus confirms the potential of correlated insulators for memory applications.

High-strength and high-toughness austenitic stainless steels based on type 316LN at 4.2 K

High-strength and high-toughness prototype steel forgings, N2, N3, and N4, were developed based on type 316LN as a cryogenic structural material. By extrapolating the proportional relationship between carbon plus nitrogen content (C + N) and 0.2 % proof stress (σ0.2) in the range of approximately 0.10–0.25 mass% C + N content, the C + N content was successfully designed to achieve the target σ0.2. To suppress the degradation of the plane-strain fracture toughness (KIC(J)) while increasing the nitrogen solid-solution content, the alloying level was designed by considering the stability of the austenite phase and stacking fault energy. The steel forgings showed a good balance of strength and toughness at 4.2 K, i.e., N2 (σ0.2 = 1142 MPa, KIC(J) = 228 MPa√m), N3 (σ0.2 = 1226 MPa, KIC(J) = 219 MPa√m) and N4 (σ0.2 = 1296 MPa, KIC(J) = 215 MPa√m). The σ0.2 and KIC(J) of ITER-grade 316LN (316LNL, 316LNM, and 316LNH) thick plates with low interstitial (C + N) content of 0.13–0.17 mass% were also evaluated at 4.2 K. Then, the effects of nitrogen content on strength and fracture toughness were successfully clarified in the full range of interstitials concentrations. An alloy design with higher Ni, Mn, and Mo contents in the chemical composition range of 316LN would be desirable for improving the fracture toughness by increasing σ0.2 due to the higher nitrogen content.

Realization of Soft Magnetic Properties in Precipitation Hardening Stainless Steel

Precipitation hardening of soft magnetic stainless steel was investigated to achieve both workability (low hardness during machining) and durability (high hardness in practical use) while maintaining soft magnetic properties. NiAl intermetallic compound was used for precipitation hardening. The relationship among aging temperature, microstructure, magnetic properties, and hardness was investigated for 22 composition samples with the basic composition of 15Cr-1Si-2Mo-3Ni-1Al-0.15Ti-bal. Fe (in wt.%) and varying compositions of Si, Mo, Ni, Al, and Cu. The maximum aged hardness was obtained by solution treatment at 1030 °C followed by aging at 550 °C. Soft magnetic properties were achieved with a single-phase ferrite composition (δ: bcc structure), and the hardness level could be adjusted with the concentration of solid solution strengthening elements. Two indexes of the relationship between microstructure and magnetic properties and between solid solution strengthening elements and hardness were obtained. The soft magnetic properties obtained by solution treatment were maintained after aging despite the occurrence of nonmagnetic precipitates of NiAl intermetallic compound. This is because precipitates do not become pinning sites for the domain wall due to their small size and distance between precipitates (1/175 and 1/26 of the domain wall, respectively). As a result, a practical precipitation hardening soft magnetic stainless steel with good properties of 227 HV after solution treatment, 372 HV and a coercive force of 64 A/m after aging treatment was realized.

Design of novel Al-Mg-(Zn-Sc) alloys with enhanced mechanical properties and corrosion resistance

The novel Al-Mg-(Zn-Sc) alloys were fabricated using vacuum induction melting and argon-protected casting method. The effects of Zn and Sc on the microstructure evolution, mechanical properties and corrosion properties of the as-cast Al-Mg-(Zn-Sc) alloys were comparatively studied. The results show that the addition of 1.5 wt% Zn facilitates the evolution of coarsen β-Al3Mg2 phases into fine T-Mg32(Al, Zn)49 phases, enhancing the resistance to intergranular corrosion (IGC) of Al-5.5Mg-1.5Zn-0.4Sc (alloy 4) with a maximum corrosion depth of 133.4 µm. The addition of Zn also promotes Mg solid solution, resulting in a 13.7 % increase in Mg solid solution concentration in Al-5.5Mg-1.5Zn (alloy 3) compared to Al-5.5Mg (alloy 2). The addition of 0.4 wt% Sc leads to the formation of smaller (∼2 µm) Al3Sc particles with a larger volume fraction of 0.96 %, providing grain refinement and improved strength in the Al-Mg alloy. Furthermore, the joint addition of Zn and Sc elements reduces the grain size by 64.0 % compared to Al-5.0Mg (alloy 1) and increases the tensile strength by 33.5 %. Alloy 4 exhibits the greatest measured tensile strength of 343 MPa. The solid solution strengthening, grain boundary strengthening and precipitation strengthening contributions to alloy 4 are calculated at 76.8 MPa, 27.9 MPa and 66.6 MPa, respectively.

Effect of Roll Load on Microstructure of Roll Cast Al-10%Mg Strip

The effect of roll load on the microstructure of an Al-10%Mg strip cast using a vertcal-type high-speed twin-roll caster was investigated using roll stop and etching with Weck’s reagent. Roll stop was adopted to investigate the transformation of the microstructute near the roll bite. Weck’s reagent was used to visually determine the of the Mg solid-solution content. The roll load was 2, 88, or 420 N/mm and the roll speed was 30 m/min. A band zone formed at the center of the thickness direction for all roll loads. The Mg solid-solution content in the αAl in the band zone obtained at a roll load of 2 N/mm was greater than that obtained at roll loads of 88 and 420 N/mm. Recrystalization migh occur in the band zone of the strip at a roll load of 2 N/mm. The Mg solid-solution content in αAl near the surface was greater than that inside the strip in the thickness direction. The Mg solid-solution content in αAl near surface obtained at a roll load of 2 N/mm was greater than that obtained at roll loads of 88 and 420 N/mm.