Alloying Elements Research Articles

Composition driven machine learning for unearthing high-strength lightweight multi-principal element alloys

High-strength, lightweight alloys are highly desired in the aerospace, automotive and marine industries. The optimization of such alloys is a multifaceted process, characterized by the consideration of diverse objectives and constraints. Various optimization methodologies exist, spanning from intricate first-principle approaches to the application of sophisticated machine learning algorithms. These algorithms might incorporate input features encompassing elemental composition, microstructural attributes, and thermodynamic properties to enhance prediction accuracies. In this work, we aim to streamline this complexity by employing solely the alloy's elemental composition as the input feature for the machine learning algorithm, improving the hardness while reducing the density of the alloy. We have curated a comprehensive database comprising 544 multi-principal element alloys and developed a robust surrogate model based on these compositions. This composition-driven model is subsequently coupled with principal component analysis (PCA) to facilitate the selection process. Remarkably, through a mere three iterations involving 14 samples, we successfully identified an alloy with an effective specific hardness surpassing the training database maximum by 8.6 %. The proposed composition-driven machine learning delineates a simplified approach for conducting optimization across multiple target material properties.

Using pulse current to tailor hydride networks while improving the strength and plasticity of pure titanium

Interstitial hydrogen atoms in titanium usually deteriorate the mechanical properties of titanium by brittle hydride phase or hydrogen-enhanced localized plasticity. In this study, hydride was used as the second phase to improve the tensile strength and elongation of TA1 pure titanium. The continuous coarse hydride network is precipitated in TA1 pure titanium after the hydrogen-charged. Then pulse current treatment is used to decompose the original coarse hydride network and reduce the size and number of hydride strips. Finally, a small uniform hydride network is formed in TA1 pure titanium. The results of tensile experiments indicate that the tensile strength of hydrogen-charged TA1 pure titanium treated by pulse current increases from the 286.4 MPa to 316.1 MPa and the elongation increases from the 47.6 % to 56.8 %. The improvement of mechanical properties demonstrate that the small and uniform hydrides can significantly improve the mechanical properties of TA1 pure titanium. In hydrogen-charged TA1 pure titanium treated by pulse current, the increment of strength is mainly caused by hard phase hydrides, and the increase in plasticity is attributed to the role of twins in coordinating deformation during plastic deformation. This study manifests that in addition to being used as a temporary alloying element to optimize the microstructure of titanium, hydrogen can also be directly act as a second phase in titanium to improve the mechanical properties.

Microstructure evolution and properties of semi-solid Al80Mg5Li5Zn5Cu5 light weight high entropy alloy prepared by SIMA

The semi-solid Al80Mg5Li5Zn5Cu5 light weight high entropy alloys were prepared by strain induced melting activation method (SIMA), and the microstructure evolution, mechanical properties and corrosion resistance of semi-solid Al80Mg5Li5Zn5Cu5 light weight high entropy alloys were investigated. The results indicate that the ideal globular or near-globular microstructures with an average grain size of 29.1 μm and a shape factor of 0.86 can be obtained when the Al80Mg5Li5Zn5Cu5 light weight high entropy alloys with 20% deformation held at 500 °C for 15 min. The coarsening coefficient is 35.8 μm3/s when the temperature is 500 °C, which is lower than the traditional single major element alloys due to the sluggish diffusion effect of high entropy alloys. The compression strength of semi-solid Al80Mg5Li5Zn5Cu5 light weight high entropy alloys is 558.4 MPa, which is 11% higher than that of as-cast state. The corrosion resistance of semi-solid Al80Mg5Li5Zn5Cu5 light weight high entropy alloys is also significantly improved.

Investigation on Be, Mg, Ca, B, Ga, C, Si, and Ge atoms doped on Al (111) surface and their effect on oxygen adsorption: A first-principle calculation

Oxygen corrosion of the aluminum alloy has a substantial impact on the durability of engineering materials and equipment. To better understand how various alloy elements affect oxygen corrosion, we used first-principle DFT method to study the role of each given dopant atom (Be, Mg, Ca, B, Ga, C, Si, and Ge) in the formation of surface oxide film on the Al (111) surface, in the case replacing a surface Al atom. Our calculations show that the electron gain or loss abilities of these alloy elements differ from that of Al metal, with Be, B, C, and Si atoms tending to penetrate into the surface, Mg, Ca, and Ga atoms protruding, and Ge atom just embedded into the Al (111) surfaces. Additionally, the type of doping element at the Al (111) surface can greatly affect the O2 absorption, predicting that Ca-doped surface absorb the least amount of oxygen, followed by Si-doped surface, with Be-, Mg-, B-, Ga-, C-, and Ge-doped surfaces showing higher O2 absorption. Based on adsorption energy (Eads) and partial density of states (PDOS) analysis, we conclude that the doped Al (111) surfaces can make O2 adsorption different owing to the difference in electronic properties of the doping atoms. These insights draw a greater knowledge of the role of alloy elements in the oxygen corrosion of Al alloys, enabling guidance for designing more corrosion-resistant materials.

The electrochemical corrosion behavior and antibacterial properties of Cu-xFe alloy

Copper-based alloys have garnered significant attention for their potential in antimicrobial applications aimed at mitigating medical-related infections. Nonetheless, the alloying elements in conventional copper alloys frequently exhibit biotoxicity. This study explored the corrosion behavior, antimicrobial activity, and ion release of Cu–Fe alloys with varying iron contents and aging treatment. The results indicate that increasing the iron content in Cu–Fe alloys and applying appropriate aging treatment can enhance both the antibacterial efficiency and corrosion rate. Transmission electron microscopy (TEM) observations revealed a corrosion mechanism in which dispersed iron phases act as nucleation sites. These nanoscale precipitates increase the Cu/Fe interfacial area, thereby promoting ion release at the interface. Furthermore, in-situ scanning electron microscopy (SEM) revealed that corrosion products are more likely to detach in iron-rich segregated areas, which effectively promotes the sustained release of copper ions.

Effect of multi-element synergistic addition on the microstructure evolution and performance enhancement of laser hot-wire cladded Fe-based alloy

To satisfy the requirements of hardness and corrosion resistance for laser additive manufacturing of hydraulic supports, this study applied the synergistic addition of C, B, Cr, Ni, Nb and Mo elements in Fe-based alloys. The multi-phases, martensite + austenite + ferrite were designed. The microstructure, hardness and corrosion resistance of the coatings were analyzed. Increasing the C and B contents could significantly increase the hardness of the coatings, while the corrosion resistance was decreased. The corrosion resistance of the coatings was determined by the Cr contents. However, increasing the Cr contents to 20.0 wt % resulted in the ferrite structure with lower hardness (21 HRC). The coatings with 0.25 wt % C, 1.2 wt % B and 19.0 wt % Cr showed the optimal matching of hardness (56 HRC) and corrosion resistance (survived in neutral salt spray test≥300h). The resulted coatings were mainly consisted of dendritic structure. Fine lath martensite phase was dominant in the dendrite regions. The interdendritic regions were consisted of nano-sized intermetallics with a mixture of σ+Nb + FeNb + Cr2Nb+(Fe,Cr)2B + NbC compounds. These interdendritic regions (14.2 GPa) showed higher hardness than that of the dendritic regions (7.1 GPa). The high Cr contents with finer dendritic structures were the major mechanisms for the excellent combination of hardness and corrosion resistance. The precipitation and growth mechanisms of the interdendritic phases were elaborated. This work provides a valuable reference for laser hot-wire cladding to prepare Fe-based alloys with high hardness and excellent corrosion resistance.

Multi-objective, multi-constraint high-throughput design, synthesis, and characterization of tungsten-containing refractory multi-principal element alloys

Refractory multi-principal element alloys (RMPEAs) have gained interest recently due to their superior properties at elevated temperatures, including outstanding yield and ultimate strengths, high thermal conductivity, and resistance to creep. RMPEAs can be designed to exhibit a wide range of properties by tailoring their composition. However, the vast chemical design space makes brute-force experimental screening inefficient and costly. In this work, we follow a closed-loop, iterative computational/experimental screening approach that combines computational alloy design methodologies with high-throughput synthesis and characterization tools to explore the vast RMPEAs space and design new RMPEAs that satisfy multiple objectives and constraints. In particular, we targeted compositions with yield strengths higher than 50 MPa at 2000 °C, W content of more than 30 at.% for high-temperature strength and operability up to 2000 °C, narrow solidification range for additive manufacturability, competitive ductility metrics, among other property constraints. We evaluated the mechanical properties and microstructure of 58 alloys designed in 5 batches, in both as-cast and homogenized conditions, synthesized using vacuum arc melting, utilizing scanning electron microscopy, X-ray diffraction, Vickers microhardness, nanoindentation, and high-temperature compression testing. Based on the microhardness screening experiments in each batch, the best-performing alloys were selected for scale-up. High-temperature compression at 1800 °C was performed in these alloys, demonstrating that the designed alloys exhibit up to five times higher yield strength than a pure tungsten benchmark. We conclude that W-containing RMPEAs designed in this study merit further consideration for next-generation structural materials for ultra-high temperature applications.

Enhancement of electrocatalytic oxygen evolution performance for FeCrNiCoTi alloys via powder modification

The development of non-precious metal catalysts with excellent performance in the oxygen evolution reaction (OER) is crucial for large-scale and low-cost hydrogen production from water. FeCrNiCoTi multi-principal element alloy (MPEA), which is free of precious metals and possesses four specific effects, holds promise as a low-cost and efficient electrocatalyst for water electrolysis. However, further enhancing the exposure of its active sites remains a challenge. To address this issue, the FeCrNiCoTi MPEA powder was long-term mechanically milled to refine the grain size, introduce defects, and (oxygen) hydroxide species with the aim of improving OER catalytic performance. Such powder milled after 80 h exhibits an overpotential of 296 mV at 10 mA/cm2 and the Tafel slope of 41.3 mV/dec, with continuous stability for 40 h in 1.0 M KOH electrolyte, comparable to the commercial RuO2 catalyst. This work provides a simple, practical and effective approach for the preparation of high-performance, low-cost OER electrocatalysts.

Effects of rare earth modifying inclusions on the nucleation mechanism and mechanical properties of MC5 roller steel

The effect of Ce treatment on the inclusions and mechanical properties of MC5 roller steel after solidification and annealing process was investigated. The implementation was observed by thermodynamic calculation, Electron Probe Micro-Analyzer and high-temperature confocal laser scanning microscopy (HT-CLSM). The results showed that as rare earth content increase, the inclusions were effectively modified into cerium oxide (Ce-O) and cerium sulfide (Ce-O-S); Compared with 0 RE steel, eliminating the proportion of inclusions larger than 5 μm by 14% and 22%; the average size decreased to 3.60 μm and 2.30 μm. Subsequently. CLSM was used to observe the aggregation, separation and agglomeration behavior of MgAlO4 inclusions and alloy elements on the surface of molten steel. Moreover. the ultimate tensile strength and yield strength of MC5 roller steel with Ce treatment increased by 12.6% and 34%. The addition of rare earths could improve the of MC5 roller steel, it provides effective reference value for subsequent industrial experiments.

Atomic insight on the electronic structure and interfacial bonding characterization of the Cu/TiC interface

The interfacial bonding characteristics of ceramic reinforced phase and metal matrix in metal matrix composites have a significant impact on their strength. Herein, the interfacial bonding properties and alloy element doping of the Cu/TiC interface in TiC-reinforced Cu matrix composites with a stoichiometric ratio of TiC of 1:1 were investigated by atomistic DFT simulations. The analysis of twelve Cu/TiC interfacial models reveals that the TiC(111) in Cu/TiC interface with C-terminated is more stable than that of TiC(111) interface with Ti-terminated due to the stronger covalent bonds formed by Cu-C. The Cu(110)/TiC(111)-C interface with the highest work of adhesion (2.871 J/m2) is the most stable interface among these Cu/TiC interfaces. Moreover, the Cu-Co/TiC interface has the highest Wad (4.223 J/m2) compared to Cu/TiC, Cu-Ni/TiC, and Cu-Zn/TiC interfaces. And the Cu-Zn/TiC interface has the lowest Wad (2.092 J/m2), which is even lower than that of the Cu/TiC interface (2.306 J/m2). During interfacial tension, the Cu/TiC, Cu-Ni/TiC, and Cu-Zn/TiC interfaces start to fracture either at the interface layer or the sub-interface layer on the Cu side, while the Cu-Co/TiC interface begins to fracture within the Cu slab. The Cu-Co/TiC interface has the highest tensile strength of 20.12 GPa at14 % strain compared to Cu/TiC (14.76 GPa), Cu-Ni/TiC (16.35 GPa), and Cu-Zn/TiC (15.30 GPa) interfaces, which is attributed to the strengthening of both the interface and sub-interface by Co doping. Thus, Co doping in the Cu matrix significantly strengthens the Cu/Ti interfacial bonding, Ni doping has a weaker strengthening effect, and zinc doping weakens the interfacial bonding.

Formation and strengthening mechanism of ordered interstitial complexes in multi-principle element alloys

Ordered interstitial complexes (OIC) are in the intermediate state between random interstitial solutes and chemical compounds, which can effectively improve the mechanical performance of multi-principle element alloys. Nevertheless, experimentally observing the complex atomic details of OIC formation and their interaction with dislocations remains challenging. Meanwhile, simulations of the OIC behavior faced the dilemma of lacking interatomic potentials for multi-component systems. In this work, we investigate the oxygen OICs in TiNbZr medium entropy alloys as a typical example to elucidate the strengthening and toughening mechanisms of OICs with a developed highly accurate deep learning potential. The formation mechanism, atomic packing of OICs and their interaction with dislocations, were then elucidated by molecular dynamics simulations with the developed potential. The interstitial atoms were found to aggregate energetically and increase the barrier of dislocation movement upon loading. It was found that the Nb content exerts a significant influence on the morphology and distribution of OICs. The decrease of Nb content favors the formation of larger cluster-like OICs. The existence of OICs can remarkably enhance the critical shear stress required for continuous dislocation movement. A pinning-cutting behavior was observed when an edge dislocation encounters an OIC, while a cross-slip behavior occurred when a screw dislocation encounters an OIC. The developed interatomic potential provides a valuable tool for elucidating the deformation mechanisms of TiNbZrO alloys, which highlights the significant effects of OICs on the mechanical performance of multi-principle element alloys.

A new synergy to overcome the strength-ductility dilemma in Al-Si-Cu alloy by adding AlZrNiTi master alloy

With the increase in lightweight components, Al-Si-Cu alloys are extensively applied in the automotive field. In this study, a multi-principal element alloy (MPEA) AlZrNiTi was designed to modify the Al-9Si-3Cu alloy, and the modification effects of individual additions of Zr, Ni, and Ti elements to the alloy were assessed. Moreover, the microstructure evolution, fracture behavior, and the mechanisms of strengthening and toughening during the modification process were investigated. Experimental results showed that when the addition amount of AlZrNiTi alloy was 0.8 wt%, significant refinements were made to the α-Al, eutectic Si, and Al2Cu in the Al-9Si-3Cu alloy, and the mechanical properties were significantly improved. In addition, the AlSiZr phase served as the heterogeneous nucleation core of α-Al was discovered. Furthermore, the AlZiTi phase was enriched at the front edge of the solid-liquid interface in solidification, hindering the growth of α-Al grains. It was also found that Al(Ni, Cu) particles with a size of 336 nm promoted the formation of high-density twins in Si crystal through the impurity-induced twin (IIT) mechanism, thereby modifying the Si phase. Comparative experiments reveal that the modification effect and mechanical properties of AlZrNiTi master adding to Al-9Si-3Cu alloy was obviously better than that of individual adding Zr, Ni, and Ti elements.

Experimental investigation of comprehensive performance by tailoring the proportion of late transition metals in quinary Fe-Co-Ni-Si-B amorphous alloys

We fabricated the Fe-Co-Ni-Si-B multi-principal element alloys by vacuum melt-spinning method. The effects of late transition metals proportion in quinary alloy ribbons on the formation, phase structure, thermal stability, microhardness, corrosion resistance and soft magnetic properties were investigated. The melt-spun structure consists of an amorphous single phase for all the specimens. The surfaces of glassy ribbons are rather flat and flawless and the average surface roughness is 0.351 nm or below. The initial crystallization temperature (Tx) and supercooled liquid region (ΔTx) of alloy system decrease by degrees with increasing Co and Ni content, showing the maximum values of 753.0 K and 60.0 K for Fe60Co10Ni10Si6B14 alloy. But the glass transition temperature (Tg) seems to barely change and maintain approximately 692.0 K. All the as-received alloy ribbons exhibit good bending ductility and acceptable Vickers microhardness ranging from 671 to 785 HV0.5. The amorphous alloy ribbons present a gradually wide passive potential range (ΔE) with the decrease of Fe content, but the corrosion current density (Icorr) becomes larger. The smallest Icorr value is 1.785 μA·cm-2 for Fe60Co10Ni10Si6B14 alloy and the widest ΔE value is about 0.272 V for Fe26Co27Ni27Si6B14 alloy. The saturation magnetization of these glassy alloys reduces from 165.0 to 112.0 emu/g as the Fe content decreases. Meanwhile, the coercivity also changes from 14.25 to 6.70 A/m. This paper offers a brand-new perspective to understand the role of late transition metals on the various physicochemical properties of quinary Fe-Co-Ni-Si-B amorphous alloys.

On novel Ni-rich phase formed during aging of an additively manufactured ultra-high strength CoFeNi alloy

The precipitation mechanism of strengthening phase of a body-centered-cubic (BCC) structured CoFeNi multi-principal element alloy produced by additive manufacturing was studied by transmission electron microscopy (TEM) and atom probe tomography (APT). The hardness of CoFeNi alloy achieved the peak value of 554.79 ± 9.86 HV after aging for 160 h at 400 °C. The CoFeNi alloy exhibited an ultrahigh compressive yield strength and ultimate compressive strength up to 1.8 GPa and 2.3 GPa respectively, whilst maintains a strain of 18.9 %. The microstructure of the alloy exhibited nanoscale lamellar Ni-rich phase with high stability homogeneously distributed in BCC matrix after aging at 400 °C. The novel Ni-rich phase containing about 50 at. % Ni with a hexagonal structure is the mainly precipitation strengthening phase, and has coherent orientation relationship with the BCC matrix in the<101>bcc∥<112¯0>Niand 111bcc∥{0001}Ni. Based on the experimental results, the precipitation mechanisms of the Ni-rich phase were discussed in detail. The current work provides a possible new direction to design high-strength alloy by introducing the novel Ni-rich phase.

A study integrating in-process thermal signatures, microstructure, and corrosion behaviour of AISI 316L coatings on low carbon steel substrate deposited by laser-directed energy deposition (L-DED)

Surface coating through Laser Directed Energy Deposition (L-DED) of AISI 316L on low-carbon steel was carried out by varying laser fluence. The resulting melt pool characteristics, obtained through IR pyrometer, played a significant role in evolution of the microstructure. A higher heat input resulted in an equiaxed grain structure with finer grain sizes and improved deposition quality. The quantitative phase analysis revealed the presence of a dominant austenite phase and a secondary ferrite phase, along with traces of molybdenum carbide. Corrosion analysis reveals improved resistance at a higher laser fluence, attributed to increased content of corrosion-resistant alloying elements (Mo, Cr) and predominance of the austenite phase. Electrochemical Impedance Spectroscopy (EIS) confirms a higher corrosion resistance at a higher laser fluence, supported by a significantly higher polarization resistance and presence of a duplex-structured passive film. Results indicate that moderate laser fluence levels, ranging from 5 to 7.5 kJ/cm2, accompanied by medium to high thermal signatures and moderate cooling rates, yield coatings with refined microstructures, enhanced mechanical strength, and corrosion resistance. For superior corrosion resistance, a laser fluence of 10 kJ/cm2 is recommended, although careful consideration of its potential impact on mechanical properties is advised.

Bond strength and interfacial analysis of six CoCr alloys made by conventional casting and selective laser melting.

To investigate the effects of the elemental composition and the manufacturing process of cobalt chromium-molybdenum (CoCr-Mo), cobalt chromium-tungsten (CoCr-W), and CoCr-Mo-W alloys on metal-ceramic bond strength. Six CoCr-based alloys were included in this study, a were classified into three different groups depending on their elemental composition (Ν = 10, for each group). The first group had molybdenum (Mo) as the third alloying element, the second group contained tungsten (W) (without Mo), and the third group included both alloying elements. The groups were further divided by the manufacturing process (casting or selective laser melting, SLM). Interfacial analysis was carried out using backscattered electron imaging (BEI) and energy-dispersive X-ray microanalysis (EDX) operating in line scan mode. The metal-ceramic bond strength was tested by a 3-point bending test according to the ISO 9693 requirements. The fracture mode of all specimens was examined under a stereomicroscope. The bond strength results were statistically analyzed by 2-way ANOVA and Tukey's multiple comparison post hoc test (a = 0.05). A continuous interface with the porcelain was found without pores, debonding areas, or other defects. Of the major elements found at the interface, Co showed the highest diffusion rate, while titanium (Ti) had the lowest diffusion rate. No statistically significant differences were identified in metal-ceramic bond strength either among materials or between manufacturing processes. The fracture mode was found to be cohesive for all specimens. The metal-ceramic bond strength is independent of the current CoCr alloy type and manufacturing process when comparing conventional casting and SLM. Interfacial analysis revealed no differences between the tested groups.

On the microstructure, corrosion behavior and surface films of the multi-principal element alloy CrNiTiV

A multi-principal element alloy consisting of equi-atomic concentrations of Cr, Ni, Ti, and V, was produced by arc melting. The CrNiTiV alloy was characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and scanning transmission electron spectroscopy (STEM), revealing a complex microstructure containing five phases. The corrosion performance of the alloy was evaluated with cyclic potentiodynamic polarization tests, indicating a low corrosion current density, a high breakdown potential and high repassivation potential. X-ray photoelectron spectroscopy and STEM were carried out after constant immersion in 0.6 M NaCl solution, revealing the passive (surface) film for each of the five phases. The Cr and V dominant phase consisted of an oxidized Cr/V-rich surface film, while the remaining four Ti-containing phases were predominantly TiO2-rich surface films. Ni enrichment and Ti deficiency were observed at the metal/oxide interface in certain Ti-containing phases.

Influence of Noble Metals on Morphology and Topology of Structural Elements in Magnesium Alloy.

The main motivation for this study was to improve implant materials. The influence of silver and gold on the structure and mechanical properties of Mg-Nd-Zr alloy was studied. In the work, quantitative and qualitative evaluation of the structural components of magnesium alloy with noble metal additives was performed. The research methods used were investigation of the mechanical properties and observation of micro- and macrostructures. The results showed that modification of magnesium alloy with Ag and Au contributes to the formation of spherical intermetallics of smaller size groups, which become additional centers of crystallization and grind the cast structure. The best composition from additional alloying with silver and gold was determined. Their positive effect on the strength and ductility properties of the metal was established. Preclinical and clinical testing was performed and the prospects for noble metal modification of bioabsorbable magnesium alloy for implant production usage were shown.

Multiple potential phase-separation paths in multi-principal element alloys

It is now well established that multi-principal element alloys (MPEAs) offer ample opportunities for exploring new compositions beyond those accessed previously by conventional alloys. However, there is one more realm of possibility presented by MPEAs that has not been touch upon thus far. Here we show that, different from conventional alloys based on a single host element, a given starting MPEA solid solution on its way towards equilibrium can take a rich variety of potential decomposition pathways via multi-stage phase separation, offering a wide range of composition destinations. If/when some of them are reached, assuming kinetically allowed, the multiple phase separation reactions one after another would lead to domains that are compositionally complex and spatially localized. This hypothetical scenario is demonstrated in this paper using a model that mimics Cr-Co-Ni MPEA, showing a preponderance of multiplicity even when assuming only fcc-based phases can form. The complex chemical heterogeneities created as such are expected to be an additional knob to turn for tuning spatially variable composition and chemical order and therefore mechanical properties. Our results thus advocate multiple phase separation possibilities with many potential paths and terminal chemical heterogeneities as yet another important characteristic that distinguishes MPEAs from conventional alloys.

Unveiling the precipitation behavior and mechanical properties in G-phase strengthened CrFe2Ni2Ti0.2Six multi-principal element alloys

In order to develop Co-free CrFeNi based multi-principal element alloys (MPEAs) with good synergies between strength and plasticity, the effects of Si content on the microstructures and mechanical properties of CrFe2Ni2Ti0.2Six (x = 0, 0.125, 0.25, 0.375, 0.5 and 0.625) MPEAs are studied in this work. The results show that the addition of Si induces a phase transformation from a single-phase face-centered cubic (FCC) structure to a dual-phase structure, comprising an FCC solid solution phase and G-phase. The outcomes from phase formation theory and phase diagram calculations (CALPHAD) also confirm that CrFe2Ni2Ti0.2Six MPEAs are prone to form dual-phase structures. With increasing Si content, the yield strength and hardness of the alloys increase by 47.2 % and 57.3 %, respectively, while still maintaining a strain of 34.2 %, which is indicative of commendable overall mechanical properties. This is ascribed to the coherence between FCC matrix and G-phase, enabling an enhancement in strength concurrently with the retention of considerable plasticity. Moreover, grain boundary strengthening and precipitation strengthening play a dominant role in the strengthening of CrFe2Ni2Ti0.2Six MPEAs. The present work offers new insights for the further development of high-performance non-metallic MPEAs, so as to achieve a combination of targeted microstructures and excellent properties.