Multicomponent Phase Diagrams Research Articles

Effect of alloying elements on coexisting phases and microstructure of M174 heat-resistant aluminum alloy

Abstract This article mainly focuses on high-power density diesel engine piston alloys, with the main component system being M174 heat-resistant aluminum alloy. On this basis, the main heat-resistant alloying elements Cu, Ni, and Fe were optimized and designed. This article is based on Thermo-Calc thermodynamic software, and comprehensively calculates and analyzes the multi-component alloy equilibrium phase diagram and Scheil non-equilibrium solidification of Al-(4-6)Cu-(1.5-3)Ni-(0.7-1.1Fe)-12.5Si-0.85Mg (mt.%) heat-resistant aluminum alloy system. Through the orthogonal experimental method of alloy composition, the phase distribution and microstructure composition of different alloy compositions are obtained. Research has found that Fe-rich phases such as Al5FeSi and Al9FeNi, as well as Ni-rich phases such as A13CuNi, A17Cu4Ni, and Al3Ni, are the main heat-resistant phases of the alloy in the temperature range of 350°C-420°C, providing important support for the high-temperature mechanical properties and creep damage resistance of piston aluminum alloy. At the same time, this article further studies the solidification history and microstructure precipitation of alloys. Fe-rich heat-resistant phases such as Al5FeSi and Al9FeNi have a higher solidification sequence. As primary and secondary phases, it is easy to generate coarse solidified structures. The organizational content is sensitive to the alloy composition. A13CuNi and A17Cu4Ni mainly precipitate in a multi-component eutectic structure, with layered and petal-shaped morphologies. The research results of this article have important theoretical significance and application value for the optimization design of high-power density piston aluminum alloy composition and the coordinated control of multi-phase structure.

The eutectic compositional space in Al-Cr-Fe-Ni system utilizing the high-throughput Calphad approach

Eutectic High-Entropy Alloys (EHEAs) show promise in balancing strength and ductility, along with excellent castability and chemical homogeneity. However, identifying optimal eutectic compositions in HEAs has been a persistent challenge, primarily due to the lacuna of multi-component phase diagrams. In addressing this challenge, the eutectic compositional space in Al-Cr-Fe-Ni is unveiled for the first time as a case study using the High-Throughput Calphad methodology. By integrating the Python application programming interface into Thermo-Calc, Latin Hypercube Sampling generated 100,000 compositions examined for eutectic formation based on thermodynamic parameters. This analysis revealed the significant correlation of valence electron concentration, enthalpy of mixing, and atomic size difference on eutectic formation. Moreover, the predictions of the proposed design methodology were compared with reported eutectic compositions, exhibiting excellent agreement. Further, a novel dual-phase eutectic alloy featuring an FCC+B2 combination predicted through the proposed design framework has been successfully cast, providing further experimental validation.

Designing a eutectic multi-principal element alloy for strength-ductility synergy

The remarkable combination of castability and strength-ductility synergy found in eutectic multi-principal element alloys featuring alternate lamellar phases is juxtaposed with the challenge of developing new compositions primarily due to the lacuna of established multicomponent phase diagrams. The present work demonstrates a systematic and simplistic single-phase plus eutectic-forming element design strategy to develop a lightweight eutectic multi-principal element alloy (EMPEA). Featuring a combination of face-centered cubic and ordered body-centered cubic phases, the vacuum arc melted alloy exhibited outstanding mechanical properties measured through digital image correlation (ultimate tensile strength of 1014 MPa with 17.5% uniform elongation), surpassing most reported as-cast EMPEAs.

Development of eutectic high entropy alloy by addition of W to CoCrFeNi HEA

High entropy alloys have shown a remarkable combination of physical and mechanical properties. The introduction of eutectic microstructure, consisting of a tough fcc phase, and a hard-intermetallic phase, can help in obtaining even better synergy of strength and ductility. The presence of multiple principal alloying elements in HEAs and absence of corresponding multicomponent phase diagrams makes designing of eutectic high entropy alloys a tedious task. In the present study, systematic investigation of CoCrFeNi-Wx system has been carried out for the development of eutectic microstructure. Experimental results validated the presence of eutectic reaction in the calculated phase diagram. CoCrFeNi-Wx HEAs remained single fcc phase alloys at smaller amount of W (x = 0.1) but changed to hypoeutectic (x = 0.25, 0.5, 0.75) and hypereutectic alloys (x = 1.0) with increase in the amount of tungsten. It has been shown that calculated pseudo binary phase diagrams can provide a very good starting point for the development of eutectic HEAs. Mechanical characterization of the developed HEAs revealed that development of eutectic mixture of a soft (fcc) and a hard phase (intermetallic/bcc) can help in obtaining outstanding combination of mechanical properties.

Three-Dimensional H–φ–θ Phase Diagram of ErB12 Antiferromagnet with Dynamic Charge Stripes

A three-dimensional (H, φ, θ, T = 2 K) magnetic phase diagram has been constructed for the first time for the antiferromagnetic metal Er11B12 with an amplitude-modulated magnetic structure exhibiting an electronic instability (dynamic charge stripes). The boundaries determining the shape of the main magnetic phases in the H–φ–θ space are reconstructed from measurements of the magnetoresistance. The role of dynamic charge stripes, which suppress the indirect Ruderman–Kittel–Kasuya–Yoshida exchange between the magnetic moments of the nearest Er3+ ions, and of the single-ion anisotropy in the formation of a complicated multicomponent phase diagram of Er11B12 is discussed.

Use of multicomponent phase diagrams of slag systems for recycling of spent automotive catalysts

Use of multicomponent phase diagrams of slag systems for recycling of spent automotive catalysts

Biophysical characterization of aberrant condensates by quantitative microscopy.

The size, composition, and dynamics of biomolecular condensates are impacted in human pathologies, including neurodegeneration and cancer. Essential biological functions such as ribosome biogenesis in nucleoli and splicing biogenesis in Cajal bodies may be compromised due to these aberrations. A further understanding of the relationship between condensate form and function may aid the development of condensate-directed therapies. Thus, we aimed to quantitatively measure the impact of disease-driving mutations in patient-derived cells with compromised Cajal bodies and nucleoli. In these cells, we surveyed classical condensate markers (e.g., Coilin and NPM1) for their ability to rescue defects in Cajal body and nucleolar size, composition, and function. To do this, a construct was employed which allowed us to independently measure the extent of overexpression and localization of the protein within the cell. Building on this, we extended the design to enable two constructs to be measured, opening the door to multicomponent phase diagrams and measuring binding in cells. Furthermore, when ALS-associated mutant proteins are over-expressed, we can measure the dosage-dependent consequences of mutant proteins in cells. Our findings suggest that at higher concentrations of disease mutant proteins essential condensate markers become mislocalized. These quantitative microscopy methods allow us to better understand the basic principles underlying the relationship between condensate form and function, which may aid therapeutic design targeting condensates.

Multicomponent Chiral Quantification with Ultraviolet Circular Dichroism Spectroscopy: Ternary and Quaternary Phase Diagrams of Levetiracetam.

Chiral molecules are challenging for the pharmaceutical industry because although physical properties of the enantiomers are the same in achiral systems, they exhibit different effects in chiral systems, such as the human body. The separation of enantiomers is desired but complex, as enantiomers crystallize most often as racemic compounds. A technique to enable the chiral separation of racemic compounds is to create an asymmetry in the thermodynamic system by generating chiral cocrystal(s) using a chiral coformer and using the solubility differences to enable separation through crystallization from solution. However, such quaternary systems are complex and require analytical methods to quantify different chiral molecules in solution. Here, we develop a new chiral quantification method using ultraviolet-circular dichroism spectroscopy and multivariate partial least squares calibration models, to build multicomponent chiral phase diagrams. Working on the quaternary system of (R)- and (S)-2-(2-oxopyrrolidin-1-yl)butanamide enantiomers with (S)-mandelic acid in acetonitrile, we measure accurately the full quaternary phase diagram for the first time. By understanding the phase stabilities of the racemic compound and the enantiospecific cocrystal, the chiral resolution of levetiracetam could be designed due to a large asymmetry in overall solubility between both sides of the racemic composition. This new method offers improvements for chiral molecule quantification in complex multicomponent chiral systems and can be applied to other chiral spectroscopy techniques.

Machine learning assisted predictions of multi-component phase diagrams and fine boundary information

A phase diagram is a critical tool in materials science, but establishing it often requires a large number of experiments, especially for multi-component systems. In this work, we propose a machine learning strategy to accurately predict the phase diagram for the multi-component ferroelectric system (Ba1−x−yCaxSry)(Ti1−u−v−wZruSnvHfw)O3 by combining classification and regression methods. Based on literature data, we construct by classification a diagram that maps composition and temperature to the phase, and identify octahedral factor, Matyonov-Batsanov electronegativity, the ratio of valence electron number to nuclear charge and core electron distance (Schubert) for the A site and B site cations as the dominant physical descriptors. A neural network (NN) regression model is adopted to accurately predict phase transition temperatures, i.e. the phase boundaries, so that a phase diagram can be established in composition space. In the region of phase boundaries, the relative proportions of coexisting phases are also estimated by their prediction probability. The predicted phase labels, location boundaries and coexisting phase proportions are experimentally validated for the ceramic (Ba0.96Ca0.02Sr0.02)(Ti0.98−xZr0.02Hfx)O3. Our work provides an effective approach to establish phase diagrams for multi-component systems and also predict fine boundary information.

Coexistence of Transient Liquid Droplets and Amorphous Solid Particles in Nonclassical Crystallization of Cerium Oxalate.

Crystallization from solution often occurs via "nonclassical" routes; that is, it involves transient, non-crystalline states like reactant-rich liquid droplets and amorphous particles. However, in mineral crystals, the well-defined thermodynamic character of liquid droplets and whether they convert─or not─into amorphous phases have remained unassessed. Here, by combining cryo-transmission electron microscopy and X-ray scattering down to a 250 ms reaction time, we unveil that crystallization of cerium oxalate involves a metastable chemical equilibrium between transient liquid droplets and solid amorphous particles: contrary to the usual expectation, reactant-rich droplets do not evolve into amorphous solids. Instead, at concentrations above 2.5 to 10 mmol L-1, both amorphous and reactant-rich liquid phases coexist for several tens of seconds and their molar fractions remain constant and follow the lever rule in a multicomponent phase diagram. Such a metastable chemical equilibrium between solid and liquid precursors has been so far overlooked in multistep nucleation theories and highlights the interest of rationalizing phase transformations using multicomponent phase diagrams not only when designing and recycling rare earths materials but also more generally when describing nonclassical crystallization.

Effect of Alloying Elements on Strengthening Phase and Solidification Structure of Ti-Al-Mo-Zr Titanium Alloy

This paper mainly studies the composition of strengthening phase, characteristic precipitation temperature and composition range of strengthening phase in Ti-Al-Mo-Zr-Si medical titanium alloy, and the influence of element changes on the content and microstructure of strengthening phase. Promote the formulation of thermodynamic process of titanium alloy powder metallurgy, as well as the formulation of alloy hot working and solid solution aging process. In this paper, Panda thermodynamic software is used to calculate the multicomponent alloy thermodynamics and multicomponent phase diagram of titanium alloy materials. The effects of Al, Mo, Zr, Si and other elements on the precipitation of strengthening phase and the phase transformation content of solidification structure were obtained. It is found that the content of Mo is more than 2 wt.% β phase transition precipitation angle. Meanwhile, in order to avoid the excess of precipitates such as Mo5Si3 and M3Si, the content of Mo should be less than 4.6 wt.%. The content of Zr can be maintained at about 1.5 wt.%. If the aging precipitation of the material is considered, it can be controlled to be less than 2 wt.%. The content of this paper is the basis and improvement of titanium powder metallurgy technology and rapid prototyping technology.

High-entropy (Hf0.25Zr0.25Ti0.25Cr0.25)B2 ceramic incorporated SiC-Si composite coating to protect C/C composites against ablation above 2400 K

The ablation behavior and protection mechanism of high-entropy (Hf0.25Zr0.25Ti0.25Cr0.25)B2 ceramic incorporated SiC–Si (HETMB2-SiC-Si) composite coating on C/C composite were investigated under ultra-high temperature (up to 2404 K) dynamic ablation test using oxyacetylene torch (OAT). Thermodynamic computations, multicomponent oxide phase diagrams, schematic diagram of the oxidation protection effect of multi-component ceramics, as well as microstructure and composition evolution analyses were built and carried out. Compared with the monolithic or conventional solid-solution diborides incorporated SiC-based composite coatings, the HETMB2-SiC-Si composite coatings presented the minor mass and thickness changes after ablation for 60 s. The oxidation-dominated ablation procedure with good resistance to mechanical scouring mainly contains the selective oxidation of each elements in the coating materials, the phase separation of the Zr, Hf and Ti (group IVB) oxides, the selective melting of Si (group IVA) and Cr (group VIB) oxides, as well as the oxygen diffusion. This resulted in differentiated oxidation scale with enhanced high-temperature thermally-stable and defect-sealing ability under different ablation environments (regions). This work provides precious and insightful information for introducing high‐entropy materials to improve the heat resistance of high-temperature thermal protection systems applied in increasingly severe environments.

Polyubiquitin effects on phase transitions of shuttle protein UBQLN2

ALS‐linked ubiquitin‐binding shuttle protein UBQLN2 mediates crosstalk between proteasomal degradation and autophagy pathways, which are thought to be controlled by interactions involving K48‐linked and K63‐linked polyubiquitin chains, respectively. We previously showed that UBQLN2 is recruited to stress granules in cells and undergoes liquid‐liquid phase separation (LLPS) in vitro. Interactions with ubiquitin or multivalent K48‐linked chains inhibit UBQLN2 LLPS. Here, we show that other multivalent chains of longer lengths, including K63‐ and M1‐linked chains and a designed tetrameric ubiquitin construct that mimics a multi‐monoubiquitinated substrate, significantly enhanced UBQLN2 LLPS over a wide range of Ub:UBQLN2 ratios. With nuclear magnetic resonance (NMR) spectroscopy and complementary biophysical techniques, we demonstrated that these opposing effects stem from differences in polyUb chain conformations, but not in affinities between polyUb chains and UBQLN2. Using microscopy and turbidity assay experiments, we obtained multi‐component phase diagrams to demonstrate that compact K11 and K48‐linked Ub4 inhibit UBQLN2 LLPS whereas extended K63 and M1‐linked Ub4 stabilize UBQLN2 LLPS. Increasing chain flexibility and accessibility to the ubiquitin binding surface enables a switch between homotypically‐driven to partially heterotypically‐driven UBQLN2 phase separation. These observations provide mechanistic insights into how UBQLN2 could differentiate between proteasomal degradation and autophagy pathways via LLPS.

Microstructure, Phase Formation and Heat-Treating of Novel Cast Al-Mg-Zn-Cu-Si Lightweight Complex Concentrated Aluminum Based Alloy

In the current work, a novel complex concentrated aluminum alloy is designed and studied. In order to investigate the unknown region of the multicomponent phase diagrams, thermo-physical parameters and the CALPHAD method were used to understand the phase formation of the Al58Mg18Zn12Cu5Si7 at.% (Al47.4Mg13.3Zn23.8Cu9.6Si6wt.%) alloy with a low-density of 2.63 g/cm3. The CALPHAD methodology showed good agreement with both the investigated microstructure and the thermodynamic parameters. The designed alloy was manufactured using an induction furnace and pour mold casting process. This study avoids the use of expensive, dangerous or scarce alloying elements and focuses instead on the utilization of widely available relatively cheaper elements. The microstructural evolution as a function of the heat-treatment was studied by means of different microstructural characterization techniques. The hardness, compressive strength and electrical conductivity of the as-cast and heat-treated alloy at room temperature were studied and correlated with the previously characterized microstructure. The alloy is characterized by a multiphase microstructure with major α-Al matrix reinforced with various secondary phases. In terms of mechanical properties, the developed alloy exhibited a high hardness value of 249 Vickers and compressive strength of 588 MPa. The present work provides a valuable insight for researchers, who aim to design and produce industry-like Aluminum based complex concentrated alloys (CCAs).

Machine Learning Assisted Predictions of Multi-Component Phase Diagrams and Fine Boundary Information

Machine Learning Assisted Predictions of Multi-Component Phase Diagrams and Fine Boundary Information

Severe Plastic Deformation and Phase Transformations in High Entropy Alloys: A Review

This review discusses an area of expertise that is at the intersection of three large parts of materials science. These are phase transformations, severe plastic deformation (SPD), and high-entropy alloys (HEA). First, SPD makes it possible to determine the borders of single-phase regions of existence of a multicomponent solid solution in HEAs. An important feature of SPD is that using these technologies, it is possible to obtain second-phase nanoparticles included in a matrix with a grain size of several tens of nanometers. Such materials have a very high specific density of internal boundaries. These boundaries serve as pathways for accelerated diffusion. As a result of the annealing of HEAs subjected to SPD, it is possible to accurately determine the border temperature of a single-phase solid solution area on the multicomponent phase diagram of the HEA. Secondly, SPD itself induces phase transformations in HEAs. Among these transformations is the decomposition of a single-phase solid solution with the formation of nanoparticles of the second phase, the formation of high-pressure phases, amorphization, as well as spinodal decomposition. Thirdly, during SPD, a large number of new grain boundaries (GBs) are formed due to the crystallites refinement. Segregation layers exist at these new GBs. The concentration of the components in GBs differs from that in the bulk solid solution. As a result of the formation of a large number of new GBs, atoms leave the bulk solution and form segregation layers. Thus, the composition of the solid solution in the volume also changes. All these processes make it possible to purposefully influence the composition, structure and useful properties of HEAs, especially for medical applications.

Grain Boundary Wetting by a Second Solid Phase in the High Entropy Alloys: A Review.

In this review, the phenomenon of grain boundary (GB) wetting by the second solid phase is analyzed for the high entropy alloys (HEAs). Similar to the GB wetting by the liquid phase, the GB wetting by the second solid phase can be incomplete (partial) or complete. In the former case, the second solid phase forms in the GB of a matrix, the chain of (usually lenticular) precipitates with a certain non-zero contact angle. In the latter case, it forms in the GB continuous layers between matrix grains which completely separate the matrix crystallites. The GB wetting by the second solid phase can be observed in HEAs produced by all solidification-based technologies. The particle chains or continuous layers of a second solid phase form in GBs also without the mediation of a liquid phase, for example by solid-phase sintering or coatings deposition. To describe the GB wetting by the second solid phase, the new GB tie-lines should be considered in the two- or multiphase areas in the multicomponent phase diagrams for HEAs. The GB wetting by the second solid phase can be used to improve the properties of HEAs by applying the so-called grain boundary engineering methods.

Microstructure and Phase Formation of Novel Al80Mg5Sn5Zn5X5 Light-Weight Complex Concentrated Aluminum Alloys

In this work, three novel complex concentrated aluminum alloys were developed. To investigate the unexplored region of the multicomponent phase diagrams, thermo-physical parameters and the CALPHAD method were used to understand the phase formation of the Al80Mg5Sn5Zn5Ni5, Al80Mg5Sn5Zn5Mn5, and Al80Mg5Sn5Zn5Ti5 alloys. The ingots of the alloys were manufactured by a gravity permanent mold casting process, avoiding the use of expensive, dangerous, or scarce alloying elements. The microstructural evolution as a function of the variable element (Ni, Mn, or Ti) was studied by means of different microstructural characterization techniques. The hardness and compressive strength of the as-cast alloys at room temperature were studied and correlated with the previously characterized microstructures. All the alloys showed multiphase microstructures with major α-Al dendritic matrix reinforced with secondary phases. In terms of mechanical properties, the developed alloys exhibited a high compression yield strength up to 420 MPa, high compression fracture strength up to 563 MPa, and elongation greater than 12%.

The Grain Boundary Wetting Phenomena in the Ti-Containing High-Entropy Alloys: A Review

In this review, the phenomenon of grain boundary (GB) wetting by melt is analyzed for multicomponent alloys without principal components (also called high-entropy alloys or HEAs) containing titanium. GB wetting can be complete or partial. In the former case, the liquid phase forms the continuous layers between solid grains and completely separates them. In the latter case of partial GB wetting, the melt forms the chain of droplets in GBs, with certain non-zero contact angles. The GB wetting phenomenon can be observed in HEAs produced by all solidification-based technologies. GB leads to the appearance of novel GB tie lines Twmin and Twmax in the multicomponent HEA phase diagrams. The so-called grain-boundary engineering of HEAs permits the use of GB wetting to improve the HEAs’ properties or, alternatively, its exclusion if the GB layers of a second phase are detrimental.

(Invited) Computational Materials Design and Data Dissemination Through the Materials Project

The Materials Project was first released in 2011 as a database containing the calculated properties of tens of thousands of materials. Since that time, its database has expanded to >130,000 materials and it has registered over 150,000 users worldwide. Today, the scope of the Materials Project includes developing interactive tools for exploring the data (e.g., multi-component phase diagrams, Pourbaix diagrams) as well as maintaining an ecosystem of open-source software tools that encompass designing, running, and analyzing the outputs of calculations. These tools have been used to design several experimentally-confirmed materials in a variety of applications, including Li-ion battery cathodes, solid state Li-ion conductors, materials for multivalent batteries, new phosphor materials, and new thermoelectric materials, to name a few. In this talk, we will present an overview of the Materials Project, including its web interface, software tools, and applications. Next, we will present new capabilities recently researched and being expanded in the near future, such as community contributed data sets through the MPContribs platform which can be used to add experimental data and connect it with the core computational data set. Finally, we discuss how the availability of and discoverability of these data sets can facilitate the discovery of new critical materials, whether that is through high-throughput screening, stimulating better theoretical method development, or by the application of machine learning methods trained on large data sets.