FCC Solid Solution Phase Research Articles

Effect of Cr content on the high temperature oxidation behavior of FeCoNiMnCrx porous high-entropy alloys

FeCoNiMnCr porous high-entropy alloys were prepared using the activation reaction sintering method with Fe, Co, Ni, Mn, and Cr as raw materials. The oxidation behaviors of FeCoNiMnCrx porous high-entropy alloys with different Cr contents, such as pore structure, the surface oxide film phase composition, structure, and morphology, were characterized by X-ray diffraction (XRD), electron probe micro analysis (EPMA), energy dispersive X-ray spectroscopy (EDS), and pore tester after high-temperature oxidation at 800–1000 °C. The results indicate that the initial porous high-entropy alloy comprises a single FCC solid solution phase. With the increase in Cr content, the average pore diameter, average porosity, and air permeability of the porous high-entropy alloy also increase. The oxidation kinetics of the porous high-entropy alloy after exposure to temperatures between 800 °C and 1000 °C follows a single-stage parabolic evolution law. At the same oxidation temperature, With the increase of Cr content, the oxidation gains gradually increased, at the same Cr content at different temperatures, the antioxidant performance of 1000 °C was the weakest, followed by 800 °C, and 900 °C showed excellent antioxidant performance. The oxidation products are mainly Mn2O3, Mn3O4, (Mn, Cr)3O4, Cr2O3and Fe2O3.

Effect of Cooling Method on Microstructure and Microhardness of CuCrFeMnNi High-Entropy Alloy

This study investigated four cooling methods for CuCrFeMnNi high-entropy alloy, namely, furnace cooling, air cooling, oil cooling, and water cooling (designated as FC, AC, OC, and WC, respectively), following a 12 h treatment at 800 °C. Results indicate that all four cooled alloys consisted of two FCC solid-solution phases (FCC1 and FCC2) and ρ phases. However, the FC alloy primarily contained FCC2 as the main phase and FCC1 as the secondary phase. The other three cooling methods yielded alloys with FCC2 as the primary phase and FCC1 as the secondary phase. With an increase in cooling rate, the content of the FCC1 phase gradually increased, that of the ρ phase initially decreased and then increased, and that of the FCC2 phase gradually decreased. The microstructure of the CuCrFeMnNi high-entropy alloy under the four cooling methods consisted of gray-black dendrites rich in Cr-Fe and white dendrites rich in Cu. Black ρ-phase particles predominated the dendrite region. As the cooling rate increased, the white interdendritic regions shrank, and the gray-black interdendritic regions expanded. The FC alloy exhibited the lowest microhardness at approximately 202.6 HV. As the cooling rate increased, the microhardness of the alloy progressively increased. The microhardness of the WC alloy was the highest, at approximately 355 HV. The strengthening mechanisms for all the alloys were primarily solid-solution strengthening and second-phase precipitation strengthening.

Fabrication of porous high-entropy Mn-Fe-Co-Ni-Cu-Zn alloys by vapor phase dealloying

Porous multicomponent 3d transition-metal (TM) alloys were fabricated by eliminating Zn from rapidly quenched ribbons with distinct compositions, TM7Zn93 and TM4Zn96 (TM – a mixture of Mn, Fe, Co, Ni, and Cu) using vapor phase dealloying (VPD). Phase composition and microstructure of the ribbons in an as-quenched state and resulting porous materials were investigated in detail by S/TEM-EDS, XRD, SEM, and EDXRF methods. In the as-quenched state, the majority of the alloy is composed of the CoZn13 type structure (C2/m space group). Atomically resolved EDS mapping clarified the chemical site occupancy of the TM elements in the structure. The resulting fabricated porous high-entropy alloys (HEA) have a spongy microstructure with a bimodal pore size and their surface area was estimated at 2–4 m2/g. Analysis of pore size distribution revealed their macro-mesoporous structure. The formation of the solid solution with the FCC (Fm3̅m space group) crystal structure during VPD was confirmed by XRD data. STEM-EDS analysis revealed the existence of several FCC solid solution phases within the porous HEA. A nanoscale elemental/phase separation into Co- and Cu-rich FCC solid solution regions with coherent interfaces across the individual crystalline grains has been found. A general route to prepare porous HEA using rapid solidification and vapor phase dealloying has been discussed.

Multi-response multi-parameter optimization of CoCrFeNiMo0.2 HEA coatings prepared by internal laser cladding and tribological behaviors

The process parameters of internal laser cladding have a significant influence on the dilution rate and hardness of CoCrFeNiMo0.2 high entropy alloy (HEA) coatings. In this paper, the influence of the key parameters for preparing CoCrFeNiMo0.2 coatings, namely laser power, scanning speed, and powder feeding rate on dilution rate and microhardness were systematically investigated. Polynomial mathematical models of the dilution and the microhardness were designed using the Response Surface Methodology (RSM), and the effects of each parameter on the objective response were investigated in depth. Then the quadratic models were used as the constraint functions and the multi-parameter multi-objective optimization algorithm was applied to find the minimum dilution rate and maximum microhardness. The algorithm was then utilized to predict the optimal combination of parameters to manufacture the internal HEA coating. Finally, the tribological behaviors of the coating were analyzed. The internal CoCrFeNiMo0.2 coating consisted of a single FCC solid solution phase. Only a small amount of hybrid texture phenomenon appeared in the coating. The coefficient of friction was approximately stable around 0.61, and the wear mechanism consisted of abrasive, adhesive, and oxidative wear. The coating has excellent tribological properties. The reliability of the RSM for the optimization of the internal HEA coating was demonstrated.

Phase formation and elemental transport in the vacuum diffusion bonding between CoCrFe0.2NiMn and CoCrFe16NiMn multicomponent alloys

To efficiently explore the influence of Fe content on the phase stability of the multicomponent CoCrFexNiMn (hereafter abbreviated as Fex) alloys. A diffusion layer with continuous, concentration gradient of Fe element is created based on diffusion couple technique. The microstructure and element distribution of the diffusion bonded layer between Fe0.2 and Fe16 alloys are analyzed. A new layer of FCC and HCP solid solution phases generates in the diffusion zone, which is consistent with the prediction of parametric approach and phase diagram calculation. As diffusion proceeds, the FCC phase is transformed from the BCC phase with the decreasing of Fe content and the HCP phase might be the transitional phase during this transition. The newly formed FCC and HCP phases are shown specific orientation relationships with the BCC phase. Elemental analysis indicated that the diffusion rate of the alloy components in the FCC phase is Cr > Mn > Co > Ni. The large concentration gradient in the diffuse interface and grain boundaries diffusion of BCC phase promoted the Fe diffusion, causing the BCC phase to transform into FCC phase.

SYNTHESIS AND INVESTIGATION OF SOME PHYSICOCHEMICAL PROPERTIES OF NANOSTRUCTURED CO-PT SYSTEM

The phase compositions and particle morphology of nanostructured Co-Pt system, obtained by the reduction of aqueous solutions of precursors with hydrazine hydrate, have been studied (for the first time in the Pt-rich region) by X-ray diffraction analysis (XRD), transmission electron microscopy (coupled with electron diffraction (ED)), thermogravimetry, small-angle X-ray scattering analysis (SAXS) and elemental analysis of the samples. As determined by XRD, with Co content less than approximately 60 at%, the only phase is determined: the face-centred cubic (fcc) phase of the solid solution of Co in Pt, with the upper limit of Co solubility in Pt equal to 18±1 at%. For Co content in the solid solution higher than its solubility limit during the synthesis, diffraction-undetectable phase (phases) is also formed in addition to the fcc solid solution phase. The presence of such phases was confirmed by the results of SAXS, and their metal nature, rather than oxide-hydroxide one, was confirmed by XRD, ED, and thermal analysis.

Designing eutectic medium-entropy alloys CoFeNiTax with outstanding mechanical properties

The eutectic medium-entropy alloys CoFeNiTax (x = 0.4, 0.5, 0.6) were designed successfully based on binary eutectic systems and thermodynamics calculations in this study. With the increase of Ta content, the solidified microstructures evolved from hypoeutectic to full eutectic and finally to hypereutectic. The primary phases in the hypoeutectic and hypereutectic were FCC solid solution and C14-Laves phase, respectively. The solidified microstructures were coarsened and spheroidized by the heat treatment, and a high-density of needle-like Laves phase precipitated in the FCC phase of the CoFeNiTa0.4. The crystallographic orientation relationship between the precipitated phase and matrix phase was [2‾ 42‾ 3]Laves//[011]FCC, and the crystal plane (1 1‾ 1)FCC was almost parallel to (0 1‾ 12)Laves, just with a mismatch angle of about 6°. The compressive strength and fracture strain of the heat-treated alloys were within 2232∼2465 MPa and 22.5–32.8 %, respectively, being superior to most high-entropy alloys. The excellent combination of strength and toughness was attributed to the synergistic effects of various strengthening-toughening mechanisms, including the second-phase strengthening, the solid solution strengthening, the interface strengthening and toughening, and the twinning toughening.

Glass-Forming Ability and Magnetic Properties of Al82Fe16Ce2 and Al82Fe14Mn2Ce2 Alloys Prepared by Mechanical Alloying

Al82Fe16Ce2 and Al82Fe14Mn2Ce2 amorphous alloys were successfully synthesized by the mechanical alloying technique. The microstructural evolution of the milled powders was thoroughly investigated employing X-ray diffraction (XRD) and scanning electron microscopy (SEM). Additionally, their magnetic properties were quantitatively evaluated by a vibrating sample magnetometer (VSM). A full amorphous structure was obtained for both alloys after milling for 40 h. During the initial milling stage, extending from 5 to 20 h, an fcc solid solution phase was formed, coexisting with the residual Al phase. The partial substitution of 2 atomic percent (at.%) Mn for Fe in Al82Fe16Ce2 did not affect the alloy’s glass-forming ability. The amorphous Al82Fe16Ce2 and Al82Fe14Mn2Ce2 powders exhibited a nearly spherical shape, with diameters ranging from 1 to 3 µm and to 10 µm, respectively. Additionally, both the Al82Fe16Ce2 and Al82Fe14Mn2Ce2 alloys demonstrated characteristics of hard magnetism.

3D finite element analysis and experimental correlations of laser synthesized AlCrNiTiNb high entropy alloy coating

A 3D Finite Element Analysis (FEA) model of laser cladding process of AlCrNiTiNb high entropy alloy (HEA) coatings on Titanium alloy (Ti6Al4V) substrate has been developed taking into account heat transfer and free surface movement. The use of Ti6Al4V is highly evident in applications such as aerospace, automobile and marine environments due to their outstanding specific strength to weight ratio. Although they have high strength useful for fabrication of engineering components and movable parts in a mechanical system, Ti6Al4V are restricted to non-friction applications as a result of their low hardness. In this work, AlCrNiTiNb HEA hard-coating with equi-atomic ratio was synthesized on Ti6Al4V alloy substrate by laser cladding technique to mitigate the limitations. Prior to experimental method, a 3D computational model was developed to simulate the physical phenomena based on heat transfers involved during laser surface cladding (LSC) of HEA coating on Ti‐6Al‐4V alloy by a laser-assisted direct energy deposition technique. COMSOL Multiphysics 5.3a was used to create a model using heat transfer in solids module incorporating temperature distribution during the layer-wise build-up of 3 layers. The experimental validation showed that the microstructural analysis by scanning electron microscope (SEM) resulted in coating having dendritic and interdendritic structure which resulted in good metallurgical bonding. X-ray diffraction (XRD) analysis displayed that AlCrNiTiNb alloy coating is composed of ordered and disordered solid solution phases (BCC and FCC) with no intermetallic compounds formed. Energy dispersive spectrometer (EDS) confirmed the presence of elements used. The microhardness of AlCrNiTiNb HEA coating reached maximum value around 892 HV which is more than of the substrate. The microhardness increased significantly due to the combination of BCC and FCC solid solution phases.

Abnormal annealing-induced strengthening in Ni39.3Al15.7Fe45 eutectic medium entropy alloy

Cold-working combined with annealing is frequently used to enhance strength of traditional alloy materials. However, this thermal-mechanical processing is not adapted to the preparation for some near net shape parts. In this paper, a dual-phase Ni39.3Al15.7Fe45 eutectic medium entropy alloy (EMEA) was prepared by vacuum arc melting and abnormal annealing-induced strengthening is demonstrated and analyzed via XRD, SEM, EDS, TEM and room temperature tensile testing. It is found that the Ni39.3Al15.7Fe45 EMEA is composed of FCC solid solution phase and BCC phase. After annealing, ordered L12 phase precipitated from FCC solid solution, which induces a significant increment of tensile strength and a weak decrease of tensile plasticity. The tensile strength and elongation are 991 MPa and 24.1 % at as-cast state, the tensile strength and elongation are 1279 MPa and 22.4 % after annealing at 700 °C for 1 h.

Effect of hot rolling and annealing on microstructure and mechanical properties of the Fe-Co-Cr-Ni-V-Zrx(x =0–5) high entropy alloys

The effect of hot rolling and annealing on the microstructural evolution and mechanical properties of the Fe25−xCo25Cr20Ni25V5Zrx (x=0, 2.5, 5) HEA with Zr variation has been investigated. The Fe25−xCo25Cr20Ni25V5Zrx (x = 0, 2.5, 5) HEA was designed using the CALPHAD approach with varying Zr content from 0 to 5 at%. The structural and microstructural characterization has been carried out by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) analysis. The microstructure of the investigated samples is found to be composed of FCC solid solution + lamellae of FCC solid solution and Ni7Zr2 intermetallic phase, which is consistent with CALPHAD prediction. Differential scanning calorimetry (DSC) analysis has also been carried out to confirm the evolution of different phases. The room temperature mechanical response of the alloys in as-cast and hot rolled annealed (HRA) conditions are evaluated by hardness and tensile testing. The hardness of the alloy increases by 70% for an increment of Zr content from 0 to 5%, respectively, which further increases after HRA. The tensile test performed on the as-cast samples shows a significant reduction in uniform elongation to 13.5% in the case of Zr5, whereas the yield strength increases by more than 125% for those compositions. After HRA treatment, the grain size and uniform elongation of the investigated samples reduced, and the yield strength further improved. The extent of grain size reduction depends on the distribution of the intermetallic Ni7Zr2 phase. The strain hardening exponent ‘n′ is found to be dependent on the grain size, and it reduces with the reduction in grain size. Also, the variation of n is dependent on the presence of the intermetallic Ni7Zr2 phase, and it is found to increase initially if the second phase is present inside the grain interior, whereas it fails to improve if the second phase is present at the grain boundary.

Microstructure and tribological performance of ultra-high speed laser-cladded AlCrCoFeNi2.1-xTiB2 (x = 0, 0.5, 1.0, 1.5 and 2.0 wt%) high-entropy alloy coatings

AlCoCrTeNi2.1- xTiB2 (x = 0, 0.5, 1.0, 1.5 and 2.0 wt%) high-entropy alloy (HEA) composite coatings were prepared on 304 stainless steel by ultra-high speed laser cladding. The microstructure, microhardness and tribological performance of HEA composite coatings were studied in detail. The results showed that HEA composite coatings all mainly consisted of BCC and FCC solid solution phase, and the addition of TiB2 didn’t change the phase structure of HEA composite coatings. The addition of TiB2 improves the microhardness of HEA composite coating. When x = 2.0 wt%, the microhardness of HEA composite coating reaches the maximum value (331.3 ± 5.0 HV), which is nearly 1.5 times that of 304 stainless steel. Accordingly, the wear resistance of the AlCoCrTeNi2.1-xTiB2 HEA composite coatings with TiB2 addition were improved, and the wear rate of AlCoCrTeNi2.1- xTiB2 HEA composite coatings showed a decreased tendency with the increase of x. However, the wear mechanism of HEA composite coatings are the same, mainly oxidation wear, adhesive wear and fatigue wear.

Influence of Al and Mo on microstructure and tribological behaviors of Co-based superalloy

In this study, three Co-based superalloys with different Al and Mo concentrations were prepared by powder metallurgy (PM) method to investigate their influences on the microstructure and tribological properties. Replacing Al with Mo in the alloy has been found to decrease its hardness and yield strength, but increases its compressive ductility at room temperature. With the increase of Mo content, the formation of the HCP phase from the original FCC solid solution phase was promoted, and the microstructure of the alloy became relatively coarse. All superalloys showed decreased friction coefficient during sliding wear at 800 °C. The alloy with the highest content of Mo and lowest content of Al exhibited the greatest wear resistance at both room temperature and 800 °C. Formation of a continuous compact glaze layer rich in Cr2O3 and CoMoO4 oxides results into a significant reduction in both friction coefficient and specific wear resistance, and the synergistic effect of high temperature wear-induced oxides is the dominant contribution rather than the transformation of HCP from the original FCC solid solution phase at high temperature.

Microstructure and wear resistance of CoCrFeNiMn coatings prepared by extreme-high-speed laser cladding

In this study, CoCrFeNiMn high-entropy alloy coatings with remarkable formability were deposited on a 316-steel substrate using conventional laser cladding (CLC) and extreme-high-speed laser cladding (EHLA) techniques. The microstructure, phase composition, element distribution, microhardness, and wear properties of the coatings prepared at various deposition speeds were analyzed. The results illustrated that the coatings comprised a stable FCC solid solution phase. The microstructure of the CLC-HEA coating was predominantly composed of columnar grains with an average size of 60.8 μm, whereas the grain size of the EHLA-HEA coating decreased to approximately 32.9 μm and 24.5 μm at deposition speeds of 20 m/min and 40 m/min, respectively. The quick cooling and heating properties of the EHLA-HEA coating finally led to a lowered dilution rate, changed grain growth orientation, and enhanced dislocation density. Furthermore, the surface hardness of the EHLA-HEA coating (251 HV) surpasses that of the CLC-HEA coating (173 HV), particularly at higher deposition speeds. The wear test analysis demonstrates a transition in wear mechanisms from abrasive to adhesive, fatigue, and oxidative wear as the load increases. Moreover, EHLA-HEA coating exhibited superior wear resistance, especially at low loads (5 N); the wear rate of EHLA-HEA coating (1.07 × 10−6 mm3N−1 m−1) deposited at 40 m/min is nearly an order of magnitude lower than for CLC-HEA coating (9.97 × 10−6 mm3N−1 m−1), which is owing to its fine sub-grain structure and its higher dislocation density.

Phase evolution and properties of AlxCoCrFeNi high-entropy alloys coatings by laser cladding

High-entropy alloys are class of structural materials that have excellent properties and are commonly used in laser additive manufacturing. In this paper, AlxCoCrFeNi (x = 0.5, 1.0, x is the molar ratio) high-entropy alloy coatings were prepared on the surface of H13 steel by using laser cladding technology. The effects of coatings on the phase composition, microstructure, element distribution, grain orientation, wear, and corrosion resistance of AlxCoCrFeNi ((x = 0.5, 1.0) coatings were analyzed. The results show that the Al0.5CoCrFeNi HEAc consists of FCC solid solution phase only, and the Al1.0CoCrFeNi coating consists of BCC/B2 solid solution phase. The microstructure changes from blocky crystals to equiaxial crystals. The average grain size decreased from 65.864 µm to 8.155 µm with the increase of Al content, and the high angle grain boundaries increased gradually with more uniform grain distribution. The average hardness values of AlxCoCrFeNi (x = 0.5, 1.0) coatings are 513.06 HV0.5 and 652.38 HV0.5, respectively. The friction coefficient and mass loss gradually decrease, and the wear form changes from abrasive wear to adhesive wear. AlxCoCrFeNi (x = 0.5, 1.0) HEAcs self-corrosion current density (Icorr) increases from 2.964 × 10−6 Acm−2 to 1.060 × 10−5 Acm−2, and the corrosion resistance gradually decreases.

Plasma nitrided CoCrFeNiMn high entropy alloy coating as a self-supporting electrode for oxygen evolution reaction

Noble metal electrocatalytic electrodes used in water electrolysis for hydrogen production are expensive and non-noble metal nanoparticle catalysts are not conducive to large-scale production. In this paper, the CoCrFeNiMn high entropy alloy (HEA) coating was prepared by high-velocity oxygen fuel (HVOF) spraying on the surface of stainless steel as a self-supporting oxygen evolution electrode, and the electrocatalytic activity of the electrode was further improved by plasma nitriding. The results show that the CoCrFeNiMn coating is mainly composed of FCC solid solution phase and MnCr2O4 spinel phase, and the thickness of the coating is approximately 100 μm. After nitriding, the surface of the coating is reshaped from the original semi-molten morphology to cauliflower-like structure, and the N atoms are mainly enriched in the MnCr2O4 phase. In addition, the binding energies of Co, Cr, and Ni to O in the nitrided coating decrease by 0.7 eV, while the binding energies of Fe and Mn to O are not significantly affected. The overpotential of the nitrided CoCrFeNiMn coating decreases from 363 mV to 309 mV at the current density of 10 mA cm−2, and it has a smaller Tafel slope and charge transfer resistance, and larger double-layer capacitance compared to the CoCrFeNiMn coating. Both the CoCrFeNiMn coated electrodes with and without nitriding show good long-term stability during the 60 h stability test. The high entropy alloy coating coupled with plasma nitriding technique provides a new research idea for the eletrocatalytic field of the water splitting.

Microstructure and Properties of Laser Cladding AlxFeCoCrNiMn High Entropy Alloy of Q345 Steel

High entropy alloy is a multi-component alloy material with equal or near atomic number, which has excellent wear resistance and corrosion resistance. In this paper, AlxFeCoCrNiMn (x = 0,0.5,1.0,1.5) high entropy alloy cladding layer was prepared by laser cladding on Q345 steel plate. The phase structure, microstructure, hardness and wear resistance of the cladding layer were studied. The results show that the cladding layer of AlxFeCoCrNiMn alloy has good metallurgical bonding ability with Q345 steel. The cladding area is mainly columnar and equiaxed. The cladding layer of AlxFeCoCrNiMn alloy is mainly composed of BCC + FCC solid solution phase, which is caused by the addition of Al element under the high entropy effect. Al element promotes the formation of BCC phase structure. With the increase of Al element, the hardness of cladding layer increases. The hardness of A1.0 cladding layer is 670HV, which is close to three times of Q345 steel. When Al (x = 1.0), the hardness of the cladding layer is the highest, and it also shows better wear resistance with lower friction and wear loss.

Study of Al Addition on Sintered CuCrFeNiTi as a Potential Alloy for Automotive Components

CrCuFeNiTiAlx high-entropy alloys (where x = 0, 0.5, 1.0, 2.5 and 5.0 mol percent or mol %) were processed through powder metallurgy. Aluminum concentration was varied in the alloy to determine its effect on the microstructure and phase formation within the CrCuFeNiTiAlx system. X-ray diffraction (XRD) studies revealed the presence of structures mainly composed of FCC and BCC solid-solution (SS) phases in the CrCuFeNiTi alloy. The addition of aluminum content is responsible for an increased volume fraction of the BCC phase on the sintered alloys. XRD results also indicate the formation of compounds of a chemical composition and crystalline structure different from those of FCC and BCC SS phases. The presence of these compounds was also confirmed through mapping of elements and punctual chemical analysis through energy dispersive spectroscopy (EDS). Bulk samples exhibited microstructures with multimodal grain size. From the microhardness test results, it was determined that addition of Al is proportional to an increase in hardness.

A Neural Network Approach to Predict Gibbs Free Energy of Ternary Solid Solutions

We present a data-centric deep learning (DL) approach using neural networks (NNs) to predict the thermodynamics of ternary solid solutions. We explore how NNs can be trained with a dataset of Gibbs free energies computed from a CALPHAD database to predict ternary systems as a function of composition and temperature. We have chosen the energetics of the FCC solid solution phase in 226 binaries consisting of 23 elements at 11 different temperatures to demonstrate the feasibility. The number of binary data points included in the present study is 102,000. We select six ternaries to augment the binary dataset to investigate their influence on the NN prediction accuracy. We examine the sensitivity of data sampling on the prediction accuracy of NNs over selected ternary systems. It is anticipated that the current DL workflow can be further elevated by integrating advanced descriptors beyond the elemental composition and more curated training datasets to improve prediction accuracy and applicability.

Microstructure evolution and compressive property variation of AlxCoCrFeNi high entropy alloys produced by directional solidification

The AlxCoCrFeNi (molar radio, x = 0.3, 0.6, 0.9 and 1.2) high entropy alloys (HEAs) were directionally solidified at the withdrawal rate of 150 μm/s. The effects of Al content on microstructure evolution, element segregation as well as compressive property were investigated. It was found that the increase of Al content resulted in the formation of BCC crystal structure. Meanwhile, the microstructure of AlxCoCrFeNi HEAs transformed from dendrite to equiaxed dendrite. The Al0.3CoCrFeNi HEA formed a single FCC solid solution phase, the Al0.6CoCrFeNi HEA consisted of CoFeCr-enriched FCC solid solution phase + NiAl-enriched BCC solid solution phase, the Al0.9CoCrFeNi and Al1.2CoCrFeNi HEAs were composed of NiAl-enriched B2 solid solution phase + CoFeCr-enriched BCC solid solution phase. Morphology of solid-liquid interface was coarse dendrite or typical dendrite. As the Al content increased, the compressive strain of directionally solidified AlxCoCrFeNi HEAs decreased from 21.26% to 18.05%, and the ultimate compressive strength increased first and then decreased. The improvement of strength results from crystal structure transition and solution strengthening. As the Al contents increased from 0.6 to 0.9, the crystal structure of AlxCoCrFeNi HEAs transformed from CoFeCr-enriched FCC structure + NiAl-enriched BCC structure to CoFeCr-enriched BCCstructure + NiAl-enriched B2 structure. The strain of Al0.3CoCrFeNi HEA was higher than others, and Al0.9CoCrFeNi HEA exhibited the maximum ultimate compressive strength of 2114.57 MPa.