Al-4 Wt Research Articles

Effect of Ce Content on Properties of Al-Ce-Based Composites by Powder-in-Tube Method

Al-Ce based alloys have gained recent interest and have proven to have excellent strength without heat treatment and high thermal stability. Challenges with the production of Al-Ce samples from elemental powders arise due to the elemental material before alloying being susceptible to rapid oxidation. The methodology for making superconductive wire, powder-in-tube, was used as a consolidate Al and Ce elemental powder, and Al-8 wt % Ce-10 wt % Mg composite powder into bulk nanostructured material. Powder samples are fabricated in an inert controlled atmosphere, then sealed in a tube to avoid oxidation of powders. Therefore, most of the powder is used without much loss. We used 316 stainless-steel tubes as a sheathing material. For Al-xCe wt % (x = 8 to 14) samples of elemental powder, liquid phase sintering was used and for Al-Ce-Mg powder solid-state sintering. Characterization of the bulk consolidated material after sintering, and before and after heat treatment, was made using optical and Scanning Electron Microscope imaging, Energy Dispersive Spectroscopy, Microhardness and Rockwell Hardness test. We demonstrated that microstructure stability in Al-Ce-based specimens can be retained after thermomechanical processing. Densification was achieved and oxidation of powder was avoided in most samples. In addition, we found that Fe and Ni in the sheathing material react with Al in the process, and Ce concentration modifies the reactivity the sheath.

Proven Anti-Wetting Properties of Molybdenum Tested for High-Temperature Corrosion-Resistance with Potential Application in the Aluminum Industry.

The behavior of Mo in contact with molten Al was modelled by classical molecular dynamics (CMD) simulation of a pure Mo solid in contact with molten Al at 1200 K using the Materials Studio®. Results showed that no reaction or cross diffusion of atoms occurs at the Mo(s)–Al(l) interface, and that molten Al atoms exhibit an epitaxial alignment with the exposed solid Mo crystal morphology. Furthermore, the two phases {Mo(s) and Al(l)} are predicted to interact with weak van der Waals forces and give interfacial energy of about 203 mJ/m2. Surface energy measurements by the sessile drop experiment using the van Oss–Chaudhury–Good (VCG) theory established a Mo(s)–Al(l) interface energy equivalent to 54 mJ/m2, which supports the weak van der Waals interaction. The corrosion resistance of a high purity (99.97%) Mo block was then tested in a molten alloy of 5% Mg mixed in Al (Al-5 wt.%Mg) at 1123 K for 96 h, using the ALCAN’s standard “immersion” test, and the results are presented. No Mo was found to be dissolved in the molten Al-Mg alloy. However, a 20% mass loss in the Mo block was due to intergranular corrosion scissoring the Mo block in the ALCAN test, but not as a result of the reaction of pure Mo with the molten Al-Mg alloy. It was observed that the Al-Mg alloy did not stick to the Mo block.

Powder metallurgical fabrication of graphene reinforced near-eutectic Al-Si matrix composites: Microstructural, mechanical and electrochemical characterization

Al-10 wt% Si matrix composites reinforced with a few-layered graphene (FLG) were fabricated via a powder metallurgical route. FLG in varying amounts (0.25, 0.5, 1, 2, and 5 wt%) was incorporated into the Al-10Si matrix via mechanical alloying (MA) for different durations in a high-energy ball mill. The mechanically alloyed (MAed) powders were consolidated by uniaxial pressing and pressureless sintering processes. The as-blended (non-MAed) and MAed powders and bulk composites were investigated comparatively in terms of microstructural, thermal, mechanical, tribological and corrosion properties. The MAed powders demonstrated refined and semi-equiaxed particle morphology with reduced crystallite size values. Additionally, the FLG/Al10Si composites exhibited advanced microstructural and mechanical properties by the contribution of MA and reinforcing particles compared to those of the as-blended and unreinforced matrix. The highest hardness and lowest wear rate values were obtained for the 4 h-MAed Al10Si-2FLG (138 HV and 6.485x10-4 mm3/N.m) and Al10Si-5FLG (178 HV and 7.456x10-4 mm3/N.m) composites. Moreover, the compressive strength of the Al-10Si matrix improved approximately by 50 and 20% via 0.5 and 2 wt% FLG addition, respectively. Also, lower corrosion resistance properties were observed for the FLG reinforced composites compared to the Al10Si matrix.

Spurious grain formation due to Marangoni convection during directional solidification of alloys in µ-g environment of International Space Station

During directional solidification of alloys in the microgravity environment of the International Space Station (ISS), growth of dendritic array is expected to be under purely diffusive transport conditions. The resulting microstructure is expected to make up uniformly arranged primary dendrites on sample cross-sections without any defects, such as macrosegregation and spurious (misoriented) grains. However, spurious grains have been seen in recently directionally solidified Al-7 wt% Si samples under the joint NASA-ESA project (MICAST) and also in SCN-0.24 wt% H2O samples grown under the NASA-PFMI project. Careful examination of both these experiments shows the presence of voids at the melt-crucible interface which are the likely source of the convective flows responsible for the fragmentation of dendrite-side arms, and their rotation which creates the nucleus for the spurious grains. In this paper, we assume that side-arm of a primary dendrite has gotten detached from the primary trunk during remelting and isothermal hold, prior to the onset of directional solidification on the Space Station, in the vicinity of a pore at the melt-crucible interface. We numerically simulate the influence of the Marangoni convection on the trajectory of such a dendrite fragment in the alloy melt and compare with the experimental observations. The experimentally observed rotation behavior of the fragmented side-arm in transparent SCN-0.24 wt% H2O, observed from the PFMI video, shows a good agreement with simulation results. The predicted rotational speeds of broken-off secondary arm in the Al-7 wt% Si (MICAST) samples is significantly higher than those in the SCN-0.24 wt% H2O (PFMI). The strength of the convection is dependent on the Marangoni Number and location of the surface pore relative to the Mushy zone. Marangoni convection is strong enough to force the rotation of broken-off side arms and should be considered an important source of microstructural inhomogeneity during terrestrial solidification processing applications.

Preparation and investigation of microstructure and wear properties of functionally graded materials of Aluminum-Nickel alloys

A functionally graded material is a high-performance engineering material that can withstand extreme working conditions without losing its properties or failing during operation. The design, fabrication, and characterization of Al-Ni integrated into single functionally graded materials are presented in this study. FGM (Al-Ni) have been successfully fabricated using the powder metallurgy process. FGMs samples are made up of five layers, starting with Al on one side and ending with Ni on the other. The FGM (Al-Ni) samples used in this research were made up of the following percentages: (100 Al, 25 Ni-75Al, 50Ni-50Al, 75Ni-25Al, and 100Ni) wt%. The samples were pressed with a load of 800 MPa and sintered at temperature 600°C for 3 hours. In this research we applied the wear test and X-ray analysis of FGM (Al-Ni) samples where the intermetallic phases that formed were (AlNi3, Al0.9Ni1.1, Ni5Al3, Al3Ni2, Al4Ni3, AlNi,), in addition to optical microscopy images.

A high activity Al–Bi@C for hydrogen generation from Al-water reaction

A high activity carbon-loaded Bi (Bi@C) is synthesized by carbonizing a home-made Bi metal coordination compound. The results show that Bi@C effectively catalyzes the Al–H2O reaction. Al–Bi@C composites are prepared by ball milling (named as Al–Bi@Cmilled) or ball milling and spark plasma sintering (SPS) (named as Al–Bi@CSPS). It can be found that the Al–Bi@CSPS obtained by sintered Al–Bi@Cmilled is converted from a powder to a block, which is beneficial for its practical application. Furthermore, the hydrogen generation performance of Al–Bi@CSPS is superior to that of Al–Bi@Cmilled. Such as the hydrogen yield of Al-5 wt% Bi@CSPS is higher than that of Al-5 wt% Bi@Cmilled (1292.0 mL g−1 vs 463.8 mL g−1), and Al-5 wt% Bi@CSPS also exhibits an excellent antioxidant ability. These results demonstrate that the SPS process is beneficial. The improvement mechanism of SPS on Al–Bi@C composites is studied by XRD, Raman spectroscopy, SEM-EDS and TEM. The fabricated Al–Bi@CSPS is expected to have practical application in the field of hydrogen supply.

A novel ultrahigh conductive Al-Cu composite produced via microwave sintering and post-treated by friction stir process

ABSTRACT Al-Cu composite materials were synthesised by powder metallurgy route via an unusual microwave sintering technique and post-treated by friction stir process. Al-100 wt.% base material resulted in a twofold increase of yield tensile strength and ultimate tensile strength with parallel enhancement in electrical conductivity when compared to AA1016. Among Al-Cu composite materials, Al-10 wt.%Cu exhibited better mechanical and electrical properties. Al-10 wt.%Cu has retained nearly 70% of the conductivity with 70% lighter weight compared to copper. It can be termed as ultrahigh conductive material compared to AA2024. Hence, this composite material can be a game-changer in replacing the heavier copper conductors in electrical applications.

Morphology and Mechanical Properties of Al- TiC Nanocomposite Processed via Ball Milling Technique

Al-TiC nanocomposites are prepared by powder metallurgy technique. The effect of milling time and TiC percent on the mechanical properties and microstructure are studied. Nano TiC powders with 5, 10, and 20 wt. % is added to the Al matrix. The mixed powders are mechanically milled by a 35:1 ball to powder ratio and 110 rpm for 6, 12, 24, and 48 hr. milling time (MT). Mixed powders are compacted by a uniaxial press under 600 Mpa and sintered at 600 °C for 1 hr. in a vacuum furnace. According to Archimedes’ principle, the density was estimated, which indicated it is decreasing for 6 hr. milling time, followed by an increase for 12 and 24 hrs., then another decreasing for 48 hrs. The addition of nano TiC increases the density values gradually by increasing its percent. Both the phase composition and microstructure of both composite powders and sintered samples are examined using XRD & FE-SEM, respectively. XRD results indicated forming the aluminum carbide (Al4C3) phase that is formed during the sintering process. The microstructure shows the homogeneous distribution of TiC on the Al matrix and the reduction of Al particle size by increasing both milling time and TiC percent. Hardness, compression strength, and wear resistance are improved by increasing TiC content and MT up to 24 hours. Al-20 wt. % TiC composite with 24 hr. milling time exhibited the highest hardness (196.5667 HV) and the lowest wear rate (0.001 g/min).

Relationship between Microstructure Evolution and Tensile Properties of AlSi10Mg Alloys with Varying Mg Content and Solidification Cooling Rates

This work explored and contrasted the effect of microstructure on the tensile properties of AlSi10Mg alloys generated by transient directional solidification depending on variations in cooling rate and magnesium (Mg) content (i.e., 0.45 and 1 wt.% Mg), with a focus on understanding the dendritic growth and phases constitution. Optical and scanning electron (SEM) microscopies, CALPHAD, and thermal analysis were used to describe the microstructure, forming phases, and resulting tensile properties. The findings showed that the experimental evolution of the primary dendritic spacing is very similar when both directionally solidified (DS) Al-10 wt.% Si-0.45 wt.% Mg and Al-10 wt.% Si-1 wt.% Mg alloys samples are compared. The secondary dendritic spacing was lower for the alloy with more Mg, especially considering the range of high growth velocities. Moreover, a greater fraction of (Al + Si + Mg2Si) ternary eutectic islands surrounding the α-Al dendritic matrix was noted for the alloy with 1 wt.% Mg. As a result of primary dendritic spacings greater than 180 μm related to lower cooling rates, slightly higher tensile properties were attained for the Al-10 wt.% Si-0.45 wt.% Mg alloy. In contrast, combining dendritic refining (<150 μm) and a larger Mg2Si fraction, fast-solidified DS Al-10 wt.% Si-1 wt.% Mg samples exhibited higher tensile strength and elongation. The control of cooling rate and fineness of the dendritic array provided a new insight related to the addition of Mg in slightly higher levels than conventional ones, capable of achieving a better balance of tensile properties in AlSi10Mg alloys.

Metal/mold thermal conductance affecting ultrafine scale microstructures in aluminum eutectic alloys

Ultra-thin microstructures of eutectic aluminum alloys have attracted attention due to their excellent mechanical properties. In this context, it is known that the massive production of industrial components may require adaptations in the processing routes with severe thermal control. Considering the benefits of molding applications, knowledge of proper conditions of the metal/mold interface is essential. The interfacial heat transfer efficiency controls the solidification kinetics and so the microstructure evolution. Furthermore, much of the existing work in this field involves the use of either water-cooled or massive copper molds. The goal is achieving moderate or fast cooling conditions and produce refined structures. In this sense, the association of the interfacial heat transfer coefficient, h, with desired microstructures can expand the application to other types of mold and process conditions. In this respect, the present research work applies a numerical mathematical model based on an inverse heat conduction problem (IHCP) for the solidification of relevant binary eutectic alloys, considered as priority for the production of ultrafine eutectics. It was demonstrated the compromise existing between the overall interfacial coefficient hg and the eutectic spacing for the Al-6.3 wt% Ni, Al-33 wt% Cu, Al-wt.12% Si and Al-1.0 wt% Co eutectic alloys. Expressions relating hg as a function of time (t) and hg versus the representative eutectic microstructural spacing (λ) of each alloy are proposed. The hg vs λ expressions allow inferring hg values necessary to induce the formation of ultrafine λ values.

Quantitative phase-field simulation of the entire solidification process in one hypereutectic Al–Si alloy considering the effect of latent heat

The multi-phase-field (MPF) model coupled with reliable CALPHAD thermodynamic/atomic mobility descriptions, appropriate faceted anisotropy and key experimental validation is employed to perform the quantitative simulation of the microstructure evolution of the hypereutectic Al-16 ​wt%Si alloy during solidification. By considering the effect of latent heat released during the eutectic phase transformation in the simulation, the appropriate entire solidification sequence is obtained. All the characteristics in the as-cast microstructure can be nicely reproduced, including the primary (Si) encircled by the second primary (Al) halo, and the coupled eutectic grains appearing at the Liquid/(Al) interface rather than Liquid/(Si) interface. Moreover, three types of growth patterns of eutectic (Si) with different lengths are distinguished according to the distance between primary (Si) and the nucleation position of eutectic (Si). Furthermore, the evaluated ratios of width to length for 50 eutectic (Si) grains due to the MPF simulation are in good agreement with the experimental data. The quantitative phase-field simulation of the entire solidification process of the hypereutectic Al-16 ​wt%Si alloy in the present work is anticipated to pave the way for revealing the grain refinement mechanism in hypereutectic Al–Si alloys in the future studies.

First-principles investigation of mechanical, electronic, dynamical, and thermodynamic properties of Al3BC

In this paper, Al-12 wt%B4C composites without and with 3 wt%Ti were fabricated via the stir-casting process, the results show that Al3BC was the main component of the reactant at the interface of B4C–Al composites. The first-principles was utilized to conduct an in-depth study of the mechanical, electronic, and thermodynamic properties, and the lattice dynamics of Al3BC. The optimized lattice parameters were agreed well with the experimental values. Al3BC had good thermal stability, but the dynamic stability was poor. The bulk modulus, shear modulus, Young's modulus, Poisson's ratio, B/G, and hardness of Al3BC are 153 GPa, 137 GPa, 317 GPa, 0.16, 1.17, and 26.43 GPa, respectively, these values indicate that Al3BC is a brittle material with high hardness and that brittle failure is the main failure form. Al3BC had a slight elastic anisotropy. It also had semiconductor properties, and its chemical bonding was covalent, metallic, and ionic.

Comparing the roles of Sb and Bi on microstructures and application properties of the Al-15% Si alloy

The roles of Bismuth (Bi) and Antimony (Sb) additions to hypereutectic Al-Si alloys with significant variation in solidification cooling rates have yet to be unraveled. Both elements are considered of importance in the production chain of Al-based metallurgical products: while Sb is a refiner of the eutectic Si, Bi remains important in applications requiring better levels of alloy machinability. Based on these verified realities, the present research aims to modify the Al-15 wt% Si hypereutectic alloy with 1.0 wt% Bi as well as with 1.0 wt% Sb. The implications of these incorporations on the characteristics of the microstructure phases and the tensile/wear properties are examined. Various samples characterized by distinct solidification rates have been generated through transient directional solidification experiments. Several methods were used to examine and compare the two alloys with each other: microstructure and segregation are investigated by CALPHAD simulations, optical microscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), whereas wear and tensile properties have been determined through standardized measurements. While adding Sb provides the growth of broken Si in the form of lamellae and some fraction of fibers for higher solidification rates, Bi alloying preserves lamellar growth for all rates examined. Adding Bi is better than Sb in reaching higher tensile properties, but Sb presence provides greater wear resistance. Both alloying elements ductilize the brittle Al-15 wt% Si alloy.

The Phase Stability of Al3Er Studied by the First-Principles Calculations and Experimental Analysis

The thermodynamics of five Al3Er compounds were investigated through first-principles density-functional theory (DFT) and experimental analysis. The Al3Er compounds with Al3Ho.hR20 (prototype Al3Ho, Pearson symbol hR20), Cu3Au.cP4, AlNd3.hP8, Ni3Ti.hP16 and Al3Gd.hR12 structures exhibited formation energies of −0.412(−0.417), −0.411(−0.416), −0.400(−0.413), −0.399(−0.345) and −0.342(−0.345) meV/atom when using DFT with “standard” potential (“frozen core” potential) of Er. The results indicated that the Al3Ho.hR20 structure was the thermodynamic stable phase and the other structures were metastable. The formation energy of Cu3Au.cP4 structure was only 1 meV/atom less than that of Al3Ho.hR20. Experimentally, the Al-30 wt.% Er alloys were cooled from 900 °C to 500 °C at the rate of 5 ± 2 °C/h and 60 ± 2 °C/h, respectively. The corresponding XRD analysis showed that the Al3Ho.hR20 was formed at the cooling rate of 5 ± 2 °C/h and the Cu3Au.cP4 was formed at the cooling rate of 60 ± 2 °C/h, which indicated that the Al3Ho.hR20 was in a thermodynamic stable phase and the Cu3Au.cP4 was in a metastable phase with high stability. The structural analysis indicated that the tiny energy difference between Al3Ho.hR20 and Cu3Au.cP4 might be attributed to a similar structure with varied stacking sequences.

Austenite/ferrite interface movement during intercritical annealing of a medium Mn steel

The austenite/ferrite interface movement during intercritical annealing of 0.15C–8.0Mn–2.1Al (wt-%) steel was simulated by DICTRA software under local equilibrium and then confirmed experimentally. The simulation results show that the austenite volume fraction exceeds the thermodynamic equilibrium amount during isothermal annealing and then decreases because the interface returns from ferrite to austenite. The reverse interface movement is verified in simulated batch annealing experiment for the first time by ex-situ determining the austenite volume fraction using characterisation of XRD as well as by in-situ measuring the bulk volume change led by phase transformation using dilatometric curves.

In Situ Investigation of the Solidification of Al-20 wt.% Zn Alloys Inoculated by Al-5Ti-1B

In situ synchrotron x-ray radiography studies on the solidification sequences of non-refined and refined Al-20Zn alloys were carried out. The dendrite growth, porosity evolution, grain densities and growth rates were measured. Without and with 0.05% grain refiner, the solidification sequences appear as columnar dendrite. The average columnar dendrite growth rate of non-refined Al-20Zn alloy is larger than refined by 0.05% grain refiner. The burst growth is happened in columnar dendrite which is the first report and the time interval was about 1.2s. The columnar interdendritic region is prone to form porosities with solidification progress. The equivalent diameter of porosity with time is well fitted by Gaussian function, and the growth velocities of porosities of all sequences are faster in the first seven seconds and fluctuated with time. When the addition level of grain refiner is larger than 0.1%, the solidification sequences appear as equiaxed dendrite. The accumulation of grains of refined Al-20Zn alloys is well fitted by logistic function. The porosities disappeared during solidification with equiaxed grains. The equiaxed dendritic growth velocity, which is ~16μm/s at a cooling rate of 8K/min, is much lower than columnar.

Influence of melt superheating treatment on cast structure of Al–Sn alloys

The study covers the effect of Melt Superheating Treatment (MST) for Al–Sn alloys. To determine the optimal superheating temperature, the authors measured the temperature dependences of the kinematic viscosity, electrical resistivity, density and surface tension of Al–Sn melts with tin contents of 10, 20, 30, 40, and 50 wt.%. According to the measurement results, the temperature t* was determined for each Al–Sn alloy sample. Heating to this temperature breaks down the micro-inhomogeneous state and leads to the heterogeneous liquid – homogeneous liquid structural transition. Melt superheating (MST) results in a decrease in melt viscosity. It was found that the temperature t* rises with increasing tin concentration in the Al–Sn melt. An increase in the tin content in the Al–Sn melt also leads to a decrease in the absolute values of kinematic viscosity and surface tension, while the electrical resistivity and density increase accordingly. Thus, the Melt Superheating Treatment (MST) mode for Al–Sn alloys was determined. The effect of MST of Al–50wt.%Sn melt on the microstructure and mechanical properties of the ingot was studied in order to determine the structural sensitivity to the degree of melt overheating, and to find a new strategy to improve the shaping ability of the Al–Sn alloy two-phase structure. The results demonstrated that the method of resistivity and viscosity determination are more sensitive and effective for melt superheating temperature (MST mode) evaluation. In addition, the desired modified Al–Sn ingot structure can be formed under normal casting conditions; MST can contribute to the modified ingot structure formation by increasing the solidification time and decreasing the average solidification rate by reducing melt viscosity after superheating.

Intermittent nucleation and periodic growth of grains under thermo-solutal convection during directional solidification of Al-Cu alloy

The presence of natural convection during solidification of alloys significantly influences the heat and mass transfer processes in the liquid phase, and thus affecting the nucleation and growth behaviors of grains. It is crucial to understand the impacts of thermo-solutal convection on the solidification process to control the final properties of casting ingots. In this study, the directional solidification of Al-15 wt.% Cu alloy under different temperature gradients has been in-situ observed using synchrotron radiation X-ray radiography. The solute distribution in the field of view (FOV) and three dimensional solid microstructure are obtained by our proposed image processing technique, which aims to determine the permeability and solutal Rayleigh number in the mushy zone over time. Then the interplay between the thermo-solutal flow and microstructure is quantitatively studied. Results indicate the solute elements are periodically discharged out of and confined to the mushy zone owing to the solutal instability in the mushy zone, which results in the periodic oscillation of solute concentration. Therefore, the oscillatory constitutional undercooling gives rise to the intermittent nucleation and periodic growth of grains, which in turn cause the periodic oscillation of permeability and the associated solutal Rayleigh number, thereby in turn resulting in the oscillation of solute concentration. Moreover, owing to the superposed solute flow and convective flow, the oscillation amplitudes of solute concentration and nucleation number vary in a sinusoidal manner in general.

Influence of nanostructured Al on the mechanical properties and sliding wear behavior of Al-MWCNT composites

In the present investigation, aluminum-based nanocomposites using multiwalled carbon nanotubes (Al-MWCNTs) were developed using nanostructured Al as a matrix and MWCNTs as nanofillers through a powder metallurgy route. The effect of nanostructured Al on the microstructure, microhardness, and sliding wear behavior of Al-MWCNT composites was studied. The crystallite size of nanostructured Al via mechanical milling for 25 h was found to be 32 nm. The major challenge associated with the development of Al-MWCNT nanocomposites is the uniform dispersion of the CNTs in the Al matrix, which was addressed by incorporating nanostructured Al. A significant improvement in the relative density, microhardness, and wear resistance of the Al-MWCNT composites up to the addition of 2 wt% of the MWCNTs was observed compared with as-received Al and its composites. The hardness of an Al-2 wt% MWCNT composite developed using nanostructured Al was 800 MPa, which was five times higher than as-received Al (170 MPa). Hardness and wear resistance found to be inversely proportional to crystallite size and porosity. The significant incremental improvement in the mechanical and wear properties mainly originates from fine-grain strengthening effects and the homogenous distribution of MWCNTs in the Al matrix. The presence of well-dispersed CNTs while maintaining structural integrity and aluminum carbide (Al4C3) crystals in the Al matrix were observed. The wear mechanism of Al-MWCNT nanocomposites was studied in detail. The wear mechanism of nanostructured Al composites has not been discussed in the literature previously; thus, this is the first comparative study of micro-and nanostructured Al-based composites.

Rod Eutectic Growth of Al-Al <sub>3</sub>Sc in Al-2 Wt. % Sc Undercooled Melt

The lack of a thorough understanding of Al-Al3Sc eutectic growth motivates the present work. We observed a rod-typed Al 3 Sc eutectic phase existing prevalently in an as-cast Al-2 wt. % Sc alloy that solidified via both slow cooling in air (~1 oC·s−1) and rapid cooling in a wedge-shaped copper mold (up to ~3000 oC·s−1), different from reported results. Al-Al3Sc eutectic dendrites were identified within a narrow region near the edge of the wedge. The eutectic dendrites have an equiaxed dendritic contour and a rod eutectic structure inside. The condition for the growth of the eutectic dendrites was assessed by using appropriate analytical models. It was revealed that an interface undercooling of 48.2 oC is required to form the eutectic dendrites, or to enter the coupled zone of the Al-Al3Sc phase diagram. A phenomenon of scientific interest is that when crystallizing under a near-equilibrium condition, the eutectic Al3Sc phase formed a non-faceted morphology, in contradiction to its faceted nature. Based on the competitive growth criterion, we deduced that the non-faceting of the eutectic Al3Sc phase essentially reduces the interface undercooling for the resultant regular eutectic, in comparison to an otherwise irregular eutectic that contains a faceted eutectic Al3Sc phase.