Calculation Of Diagrams Research Articles

Design and fabrication of multiphase TiVCrZrW films with superior wear resistance and corrosion resistance

High entropy alloys (HEAs) have the potential to overcome the conflict between hardness and toughness by incorporating dual-phase or multiphase structures. Under unbalanced magnetron sputtering, HEA films with large atomic size differences tend to form non-monophasic structures. In this study, based on a phase diagram calculation simulation, a multiphase TiVCrZrW film with deposition temperature-induced phase separation was successfully designed. Interestingly, the TiVCrZrW film deposited at 600 °C exhibited a multiphase structure including a double body-centered cubic (BCC) phase and Laves phase by spinodal decomposition, realizing a balance between hardness and toughness. The tribological experiments showed that the multiphase TiVCrZrW film provided superior wear resistance, with a minimum wear rate of 2.63 × 10−6 mm3/(N·m). The electrochemical experiment demonstrated the outstanding corrosion resistance of the multiphase TiVCrZrW film, and the corrosive solution was effectively inhibited by the ZrO2 and Cr2O3 oxides passive film formed on the surface. According to the results of this study, TiVCrZrW protective films have a wide range of potential applications in various fields of marine engineering.

π-π scattering lengths: Electric corrections in the linear sigma model

In the frame of the linear sigma model and working in the weak field approximation, we discuss the role played by an external electric field on the behavior of π-π scattering lengths. For this purpose, we have considered all relevant one-loop diagrams in the s, t, and u channels where we have Schwinger propagators for charged pions. An important novelty of our analysis, compared with previous existing discussions in the literature, is the explicit calculation of box diagrams which were previously not considered in discussions regarding magnetic corrections to π-π scattering lengths. Our analysis shows that electric field corrections have an opposite effect with respect to the previously calculated magnetic corrections.

Comparative Study on the Effect of External Magnetic Field on Aluminum Alloy 6061 and 7075 Resistance Spot-Welding Joints

This study investigates the effects of the external magnetic field on the microstructure and mechanical property aluminum alloy 6061-T6 and 7075-T651 resistance spot welding joints. The melting behavior of 6061 and 7075 was analyzed via the calculation of the phase diagram (CALPHAD) technique. The CALPHAD results indicate that, for the 6061 aluminum alloy, the liquid fraction shows a minimal increase at the beginning stage during the solid–liquid phase transition process but with a sharp rise at the ending stage (near the liquidus). In contrast, for the 7075 aluminum alloy, the liquid fraction gradually increases throughout the entire solid–liquid phase transition process. The differences in melting behavior between the 6061 and 7075 alloys lead to different liquation crack morphologies in their spot-welded joints. In the 6061 alloy, the cracks tend to be “eyebrow-shaped”, allowing the liquid metal in the nugget to feed the gaps, and this does not significantly compromise the mechanical properties of the joint. In contrast, the 7075 alloy develops slender cracks that extend through the partially melted zone (PMZ), making it difficult for the liquid metal to feed these gaps, thereby significantly deteriorating the joint’s mechanical strength. Compared to conventional resistance spot-welding joints, the heat exchange between the nugget and the workpiece is enhanced under the external magnetic field, leading to a wider PMZ. This exacerbates the detrimental effects of liquation cracks on the mechanical properties of the 7075 joints. Lap-shear tests indicate that the mechanical properties of the 6061 aluminum alloy joints are improved under electromagnetic stirring. For 7075 aluminum alloy joints, the mechanical properties improve when the welding current is below 34 kA. However, when the welding current exceeds 34 kA, because the widening of the PMZ increases the tendency for liquation cracks, the joint’s mechanical property is deteriorated.

A novel treatment of solute drag and solute trapping at a solid–liquid interface during rapid solidification of multicomponent alloys

AbstractIn response to the renewed interest in solute drag and solute trapping models fueled by their applications to additive manufacturing, a novel treatment is proposed to describe the diffusional behaviors of solute at a migrating solid–liquid interface during rapid solidification of multicomponent alloys. While the treatment is still built on irreversible thermodynamics and linear kinetic law, its novelty lies in breaking up the classical trans‐interface diffusional flux into two separate fluxes one is the transferred‐back flux with its ending point at the interface and the other is the bumping‐back flux with its starting point at the interface. This novel treatment entails three significant improvements in reference to the existing models. Firstly, it reveals that the degree of solute drag is dependent on the ratio of liquid diffusive speed over interface diffusive speed. Secondly, a novel relation between the distribution coefficient and interface velocity is derived. It amends the confusing behavior seen in Aziz’s without‐drag continuous growth model. Thirdly, the proposed treatment eliminates the need of prescribing the degree of solute drag parameter for the kinetic phase diagram calculation. The numerical solution to the proposed model is presented, and it is ready to be used for the kinetic phase diagram calculation.

Development of Cost-Effective Sn-Free Al-Bi-Fe Alloys for Efficient Onboard Hydrogen Production through Al–Water Reaction

Leveraging the liquid-phase immiscibility effect and phase diagram calculations, a sequence of alloy powders with varying Fe content was designed and fabricated utilizing the gas atomization method. Microstructural characterizations, employing SEM, EDS, and XRD analyses, revealed the successful formation of an incomplete shell on the surfaces of Al-Bi-Fe powders, obviating the need for Sn doping. This study systematically investigated the microstructure, hydrolysis performance, and hydrolysis process of these alloys in deionized water. Notably, Al-10Bi-7Fe exhibited the highest hydrogen production, reaching 961.0 NmL/g, while Al-10Bi-10Fe demonstrated the peak conversion rate at 92.99%. The hydrolysis activation energy of each Al-Bi-Fe alloy powder was calculated using the Arrhenius equation, indicating that a reduction in activation energy was achieved through Fe doping.

Effect of Cr:C ratio on open three-body wear resistance of squeeze cast high chromium cast iron

A series of high chromium white cast iron (HCCI) alloys with varying Cr:C ratios were designed and fabricated through the squeeze casting process. This study investigates the effect of the Cr:C ratio on the mechanical properties, microstructure, phase diagram, and both low-stress and high-stress abrasion performance of HCCIs. Alloys with a very high Cr:C ratio exhibited better impact toughness but poorer hardness. Scanning electron microscopy (SEM) and phase diagram calculations elucidated the influence of the Cr:C ratio on microstructure, carbide volume fraction, and carbide type. Abrasion resistance was evaluated using impact abrasive wear (high-stress) and rubber-wheel (low-stress) abrasion on quartzite in open three-body wear. Comprehensive assessments under impact abrasive wear and rubber-wheel abrasive wear conditions suggest that the alloy achieves optimal abrasion resistance with a Cr:C ratio ranging from 8 to 11. Post-wear analysis reveals that surface damage varies between high-stress and low-stress conditions. The microstructure of squeeze HCCIs is significantly influenced by the Cr:C ratio, resulting in diverse operative wear mechanisms, including micro-cutting and micro-fracture. Successful adjustment of the Cr:C ratio led to the attainment of a nearly eutectic HCCIs composition suitable for squeeze casting.

The origin of broadband blue emission in zero-dimensional organic lead iodine perovskites: A first-principles study.

Broadband blue emission in zero-dimensional perovskites has received considerable attention, which is very important for the realization of stable blue-light emitters; however, the underlying formation mechanism remains unclear. Based on first-principles calculations, we have systematically studied the self-trapped excitons (STEs) behavior and luminescence properties in 0D-(DMA)4PbI6 perovskite. Our calculations show that there is a significant difference between the intrinsic STE luminescence mechanism (∼2.51eV) and experimental observations (∼2.70eV). In contrast, we found that the iodine vacancy (VI) is energetically accessible and exhibits a shallow charge transition level at ∼2.69eV (0/+1) above the valence band maximum, which provides the initial local well for the STEs formation. Moreover, the low electronic dimension synergistic Jahn-Teller distortion facilitates the formation of extrinsic excitons self-trapping. Further excited state electronic structure analysis and configuration coordinate diagram calculations confirmed that the broadband blue emission in 0D-(DMA)4PbI6 is the origin of VI-induced extrinsic STEs instead of intrinsic STEs. Therefore, our simulation results rationalize the experimental phenomena and provide important insights into the formation mechanism of STEs in low-dimensional perovskite systems.

A synchronous improvement of strength and elongation caused by solid solution in low-silver SAC solder with superior necking resistance properties

The current SAC(Sn–Ag–Cu) solder often experiences rapid degradation of mechanical properties at high temperatures and is prone to fracture under dynamic loads, thus failing to meet the interconnection requirements of industrial electronic products that operate under high power and vibration loads. In light of this, this paper aims to enhance the overall performance of the alloy by reducing the fraction of the second phase in SAC305 alloy, altering the type of second-phase particles, and strengthening the matrix β-Sn phase. Additionally, based on thermodynamic calculations of phase diagrams, the internal phases and elemental solid solubility of the alloy under different temperature conditions are accurately designed, thereby improving the alloy's strength while maintaining its elongation almost unchanged. The experimental results indicate that the designed Sn1.0Ag0.7Cu–3Bi4In1.5Sb alloy exhibits a higher rate sensitivity factor m (0.0559), which is more than double that of the Sn1.0Ag0.7Cu–5Bi4In3Sb alloy (0.0239). This improvement is primarily attributed to the enhanced interaction between the matrix β-Sn and the solid solution effect. Larger compound phases, such as Cu6Sn5 and Ag3Sn, only play a role in the low-rate loading region. Additionally, the alloy demonstrates strong temperature dependence, which is also related to the dissolution of the In element in the matrix β-Sn. The solid solution of the In element significantly enhances the high-temperature elongation rate of the alloy, increasing from 11.9% at low temperatures to 21.3% at high temperatures. The successful development and implementation of this research provides a new solution for interconnection of electronic devices under high-speed dynamic loading and high-temperature service.

Calculation of critical endpoints and phase diagrams of highly asymmetric binary systems

The computation of Global Phase Equilibrium Diagrams (GPED) for binary systems, including critical and three-phase equilibrium curves, is crucial for analyzing process conditions and assessing thermodynamic models. In the past two decades, algorithmic strategies and GPEC software have become essential tools. However, numerical problems can arise with the original algorithm for highly asymmetric systems, such as gases or water with heavy compounds or polymers, hindering the completion of GPED and related diagrams.This study presents an innovative calculation methodology to address these challenges. Our approach extends existing algorithms to achieve automatic GPED generation without user intervention, focusing on nearly pure phases. We apply our methodology to systems such as methane or water with heavy alkanes, and CO2 + silicones. The proposed algorithmic strategies effectively handle asymmetric systems, different types of phase behavior, and the estimation of extremely low concentrations in nearly pure phases along the vapor-liquid-liquid equilibrium curve.

Evaluation and quantification of diffusion wear between cutting chip and workpiece using forging press

The state of the interface between the workpiece and the cutting tool affects the cutting temperature and pressure on the tool surface during the cutting process. In particular, while cutting difficult-to-cut materials such as Ni-based alloy 718, the workpiece exhibits a high affinity for cutting tool materials and could easily adhere to them. Adhesion can, at times, adversely affect productivity. The diffusion between the cutting tool and the workpiece is a factor considered to contribute to the adhesion phenomenon during cutting. Addressing this issue involves choosing tool materials and coated materials with high resistance to diffusion and optimizing cutting conditions, particularly the cutting speed, which significantly impacts cutting temperature. However, because cutting tool wear comprises various forms, clarifying the effect of diffusion on tool wear remains open. In this study, to reproduce the diffusion phenomenon between cutting tool and workpiece, two pairs of test specimens were prepared: (1) cemented carbide-AISI 1045 and (2) cemented carbide-Alloy718, which could be held at high temperature under vacuum conditions by a forging press. The degree of diffusion phenomena was evaluated at each tool-work material interface, and the quantification of diffusion amount was performed by diffused element in each work material. Additionally, the theoretical analysis of the diffusion phenomenon using the thermodynamic and phase diagram calculation software Thermo-Calc was also performed.

Effect of Zn Addition on Phase Evolution in AlCrFeCoNiZn High‐Entropy Alloy

The addition of Zn to AlCrFeCoNi high‐entropy alloy (HEA) poses intriguing questions as to how it would affect phase evolution. Herein, the phase evolution in AlCrFeCoNiZn is studied using a combination of experimental techniques (X‐ray diffraction, scanning electron microscopy, energy‐dispersive spectroscopy, and differential scanning calorimetry) and computational (density‐functional theory [DFT], calculation of phase diagrams, and machine‐learning) methods. Mechanically alloyed and spark‐plasma‐sintered AlCrFeCoNiZn assumes a metastable single‐phase, body‐centered‐cubic (BCC) structure that undergoes diffusion‐controlled phase separation upon subsequent heat treatment to form separate (Al, Cr)‐rich, (Fe, Co)‐rich, and (Zn, Ni)‐rich phases. The formation of (Al, Cr)‐rich phase, not reported previously in AlCrFeCoNi‐based HEAs, is attributed to strong clustering tendency of Cr–Zn and Cr–Ni pairs, combined with the strong ordering of Zn–Ni pair, driving out Cr that in turn combines with Al to form a (Al, Cr)‐rich phase. In the DFT results, the formation of thermodynamically stable L12 phase is shown wherein Cr–Fe–Zn [Al–Ni‐Co] preferably occupy1a (000) [3c (0 ½ ½)] positions. The sluggish diffusional transformation to L12 phase from BCC precursors is attributed to the small stacking‐fault energy of AlCrFeCoNiZn. The equilibrated HEA exhibits a high microhardness of 8.24 GPa with an elastic modulus of 184 GPa.

Analysis of Thermophysical Properties of Electro Slag Remelting and Evaluation of Metallographic Cleanliness of Steel.

Improving the competitiveness of steel companies is linked to sustainable, quality-compliant steel production. Therefore, new steel production technologies contributing to increased cleanliness of steel are continuously being developed and optimized. One way to achieve a high steel quality is to use electro slag remelting (ESR) technology. In this paper, the principle of ESR technology and the importance of fused slags for optimizing the process are outlined. The aim of this work was to analyze the main thermophysical properties of steel and fused slags used in the ESR process. Determination of the properties of steel and slags was performed using the FactSage calculation software, which involved the calculation of the liquid and solid temperature of steel and slags, the calculation and construction of quaternary diagrams, and the calculation of viscosity. The resulting quaternary diagrams revealed the substantial influence of chemical composition on melting temperatures of slags. In order to validate the acquired results, a CrNiMoV-type steel was subjected to investigation of its metallographic cleanliness and evaluation of its mechanical properties; the ESR process was shown to significantly improve the cleanliness of the steel and improve the mechanical properties of the steel compared to its cleanliness and quality when produced via vacuum degassing (VD) technology. During the ESR process, the average size of non-metallic inclusions was reduced from 20 μm to 10 μm, and the maximum size of non-metallic inclusions was reduced from 50 μm to 28 μm. The mechanical properties of the steel produced using ESR technology were impacted as follows: the ductility increased by 10%, contraction increased by 18%, notched toughness at 20 °C increased by 46%, and at -40 °C (respectively -50 °C) it increased by 30%.

Ultrahigh electromechanical response from competing ferroic orders

Materials with electromechanical coupling are essential for transducers and acoustic devices as reversible converters between mechanical and electrical energy1–6. High electromechanical responses are typically found in materials with strong structural instabilities, conventionally achieved by two strategies—morphotropic phase boundaries7 and nanoscale structural heterogeneity8. Here we demonstrate a different strategy to accomplish ultrahigh electromechanical response by inducing extreme structural instability from competing antiferroelectric and ferroelectric orders. Guided by the phase diagram and theoretical calculations, we designed the coexistence of antiferroelectric orthorhombic and ferroelectric rhombohedral phases in sodium niobate thin films. These films show effective piezoelectric coefficients above 5,000 pm V−1 because of electric-field-induced antiferroelectric–ferroelectric phase transitions. Our results provide a general approach to design and exploit antiferroelectric materials for electromechanical devices.

Improved phase-state identification bypass approach of the hydrocarbons-CO2-H2O system for compositional reservoir simulation

CO2 injection is a highly effective technique to enhance oil recovery, achieved through continuous or alternative injection. However, the intricate interactions between different phases within porous media present significant challenges when predicting the performance of CO2 injection. To address this, it is crucial to employ compositional simulation, which accounts for the multiphase multicomponent transport. Nonetheless, conventional multiphase flash calculations can be computationally inefficient for large-scale reservoir simulations. Therefore, it is necessary to accelerate the Equation-of-State (EoS)-based compositional simulation, given the widespread use of CO2 enhanced oil recovery (CO2-EOR) in recent years. The phase-state identification bypass method has proven to be superior to other methods in terms of efficiency. However, this approach struggles with regions near phase boundaries, resulting in reduced computational efficiency in those areas.In this study, an enhanced phase-state identification bypass approach is developed to address this limitation. The first step involves discretising the pressure-temperature space using rectangular grids. Additionally, the tie-simplexes, which represent regions defined by the maximum number of phases formed by the fluid under consideration, are discretized in the phase-fraction space at the pressure and temperature of each discretization node. Subsequently, the discretization grid associated with the given point (the overall composition, pressure, and temperature) is located, and the phase states of the grid nodes are determined using the conventional multiphase flash method. If all nodes exhibit the same phase state, that phase state is assigned to the given point. However, if multiple phase states are obtained, a novel process is proposed to determine the phase state of the given point. To validate this improvement to the phase-state identification bypass method, phase diagram calculations and simulation cases are conducted, and the results demonstrate the robustness of the proposed method and its superior computational efficiency compared to the previous method.

Late Jurassic High-Pressure Metamorphism of Variscan I-Type Granitoids in the Northern Part of the Pelagonian Unit (Republic of North Macedonia)

Abstract The high P/T metamorphic Pelagonian Unit in the Republic of North Macedonia comprises (1) a Variscan basement consisting of gneisses, schists and minor meta-mafic rocks, which are all intruded by I-type granitoids and rare related dikes; (2) a metamorphosed sedimentary sequence of Permian to Lower Triassic age, and (3) a sequence of calcite and dolomite marbles resulting from Late Triassic to Middle Jurassic carbonate sediments. All these rocks underwent a common high-P/T metamorphism of Late Jurassic age. This paper deals with the metamorphism of the Variscan I-type granitoids which contained the igneous mineral assemblage plagioclase I + alkali feldspar I + quartz I + biotite I + titanite I + allanite I + zircon I + apatite I ± magnetite I. During Late Jurassic high-P/T metamorphism, these undeformed granitoids were thoroughly metamorphosed under isotropic pressure conditions as documented by undeformed granitic textures that are overgrown by metamorphic minerals such as garnet II, epidote II, and phengite II. Various, eventually metasomatic mineral reactions took place in different textural positions: (1) Former igneous plagioclase grains became completely transformed to Na-rich plagioclase IIa (An09–14) containing numerous small grains of epidote IIa and phengite IIa. Either this transformation was an allochemical one and was accompanied by the syn-metamorphic introduction of an aqueous fluid phase containing Fe, Mg and K or, alternatively, the more Ca-rich parts of plagioclase I became considerably sericitized before high-P/T metamorphism, and the resulting mixture of more Na-rich relic plagioclase with its sericite-rich domains became later metamorphosed under high-P/T conditions. In the first case, an aqueous phase is needed during metamorphism, while in the second case high-P/T metamorphism might have proceeded under H2O-undersaturated conditions; (2) igneous alkali feldspar I was changed to albite-poor orthoclase II or microcline II; (3) igneous Ti-rich biotite I reacted with plagioclase to metamorphic garnet II + Ti-poorer biotite II + titanite II + phengite II + quartz II ± epidote II ± rutile II, which is rimmed by Ttn II. At textural positions, where igneous plagioclase I was not available, igneous biotite I was transformed to Ti-poorer biotite II + titanite II ± ilmenite-hematite II; (4) during uplift, high-P/T metamorphic rutile II became marginally overgrown by titanite II ± ilmenite II; (5) igneous allanite I grains stayed unaltered, but when located near to former plagiocase I, they became partially rimmed by metamorphic epidote II. Equilibrium phase diagram calculations showed that the observed metamorphic paragenesis (plagioclase II + K-rich feldspar II + biotite II + garnet II + epidote II + phengite II + garnet II + quartz II + rutile II + titanite II) is only stable under H2O-unsaturated conditions. The I-type granitoids and their metamorphic country rocks were metamorphosed under high-P/T conditions of 1.3 to 1.5 GPa and 560 to 590 °C.

Anionic vacancy filled-up mechanism in (Ti0.2V0.2Nb0.2Ta0.2W0.2)Cx high-entropy carbide

Carbothermic reduction for high-entropy carbide preparation has it’s promising potential for industrialization application and the relevant basic theory for formation process required to clarify urgently. This research reports the anionic vacancy filled-up (AVF) mechanism during the formation of (Ti0.2V0.2Nb0.2Ta0.2W0.2)Cx high-entropy carbide powder by predictions of first-principles calculations, thermodynamic phase diagram calculations and verification by experimental preparation and characterization. The mechanism demonstrated that the rock-salt carbide matrix with superfluous anionic vacancy was formed firstly and the residual carbon substance continuously occupied the vacancies to an equilibrium state. The origin of the equilibrium anionic vacancy concentration was revealed from the perspective of the energy variation.

Microstructures and wear properties of CoCrFexNi (x = 0, 1) medium-entropy alloy coatings prepared by laser cladding

PurposeHigh-nitrogen steel is a common material for the manufacture of drilling equipment such as drill collars. However, its poor surface properties often limit its applications. The purpose of this paper is to find a way to enhance the surface performance of high-nitrogen steel, which is expected to improve the wear resistance of high-nitrogen steel.Design/methodology/approachThe CoCrNi and CoCrFeNi medium-entropy alloy (MEA) coatings were prepared on high-nitrogen steel substrate by laser cladding technology. The microstructure, phase composition and element distribution of the fabricated coatings were investigated using scanning electronic microscopy, electron backscatter diffraction and X-ray diffraction. The phase structure, phase stability and structural stability of the CoCrNi and CoCrFeNi MEAs were investigated in combination with phase diagram calculation and molecular dynamics. Then the wear tests were carried out for coatings.FindingsThe results show that both prepared MEA coatings have good quality and contain a single face-centered cubic phase. The wear performance of MEA coatings is improved by the refinement of grain size and the increase of dislocation density. Due to the addition of Fe atoms, the lattice distortion of the CoCrFeNi system increased, resulting in a higher dislocation density of the coating. Cr atoms in the CoCrFeNi system are the largest, and the local lattice distortions induced by them are greater. Through this study, MEA coatings with high hardness can be expanded to drilling field applications.Originality/valueCoCrFeNi and CoCrNi MEA coatings were successfully prepared on the surface of high-nitrogen steel for the first time without obvious defects. The micromorphology and grain orientation of the different kinds of coatings were discussed in detail. The hardness-strengthening mechanism and structure stability of the coatings were illustrated by experiments and molecular dynamics simulations.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0116/

Effect of CaO/Al2O3 Ratio in Fluorine‐Free Refining Slag with Low Basicity on the Cleanliness of SWRS82B Steel

A fluorine‐free quaternary CaO–Al2O3–SiO2–MgO refining slag for SWRS82B coil steel is studied by considering the requirements of the steel wire. Laboratory experiments are conducted to study the equilibrium and kinetics of steel–slag reactions. The physical and chemical properties of refining slags, including the melting temperature, viscosity, and MgO solubility, are estimated by FactSage7.2 calculation. The cleanliness of SWRS82B steel refined by slags with a basicity of 1 and C/A ratio in the range of 1.36–7.13 is studied systematically. The plasticity of inclusions is studied by phase diagram and Young modulus calculation. Deoxidizing capacity and desulfurization capacity of refining slags are discussed by kinetic calculation of steel–slag reactions based on FactSage7.2 macro‐editing and the kungliga tekniska högskolan model. Slag with a composition of 42%CaO–47%SiO2–4%Al2O3–7%MgO has the best refining effect, in which impurity elements are lowest and plastic inclusions with the smallest size and least quantity are obtained. The impurity elements oxygen and sulfur in steel can be controlled for 29 and 75 ppm, respectively. The average size of inclusions is 1.54 μm. The majority of inclusions are in a liquid state at 1600 °C and Young modulus of the inclusions ranges from 99.78 to 152.87 GPa.

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.

CALPHAD-guided investigation on enhancing NiAl bronze properties and microstructures evolution with Mn addition

The effect of Mn addition on microstructures and properties of as-cast NiAl bronze was systematically investigated in this study. Phase diagram calculations (CALPHAD) were employed to investigate the phase transformation process, composition, and fraction of Cu-10Al-5Fe-5Ni-xMn (x = 0, 1.5, 4.5, 7 wt%) alloys. With the increasing Mn element, the β phase region expands, and the precipitation temperature of κⅢ phase increases while the κⅣ phase decreases. The microstructure characterization and quantitative analysis reveal significant morphology changes. The polygonal α-Cu phase transforms to the acicular α-Cu phase while the fraction of κⅢ phase increases. The atomic-scale interface between the κⅢ/α and the composition of the κⅢ phase are analyzed using transmission electron microscopy. The results indicate that the κⅢ phase exhibits a Nishiyama-Wasserman (NW) orientation relationship with the α-Cu phase in Mn-containing alloys. Additionally, optimal mechanical properties of UTS = 795 MPa, YS = 438 MPa are achieved with the addition of 4.5 wt% Mn, while the best EL = 20.8 % is attained with 1.5 wt% Mn.