Decoupling between calorimetric and dynamical glass transitions in high-entropy metallic glasses

Abstract Glass transition is one of the unresolved critical issues in solid-state physics and materials science, during which a viscous liquid is frozen into a solid or structurally arrested state. On account of the uniform arrested mechanism, the calorimetric glass transition temperature (Tg) always follows the same trend as the dynamical glass transition (or α-relaxation) temperature (Tα) determined by dynamic mechanical analysis (DMA). Here, we explored the correlations between the calorimetric and dynamical glass transitions of three prototypical high-entropy metallic glasses (HEMGs) systems. We found that the HEMGs present a depressed dynamical glass transition phenomenon, i.e. HEMGs with moderate calorimetric Tg represent the highest Tα and the maximum activation energy. These decoupled glass transitions from thermal and mechanical measurements reveal the effect of high configurational entropy on the structure and dynamics of supercooled liquids and metallic glasses, which are associated with sluggish diffusion and decreased dynamic and spatial heterogeneities from high mixing entropy. The results have important implications in understanding the entropy effect on the structure and properties of metallic glasses for designing new materials with plenteous physical and mechanical performances.

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Decoupling between calorimetric and dynamical glass transitions in high-entropy metallic glasses

Nature Communications ◽

10.1038/s41467-021-24093-w ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jing Jiang ◽

Zhen Lu ◽

Jie Shen ◽

Takeshi Wada ◽

Hidemi Kato ◽

...

Keyword(s):

Glass Transition ◽

Metallic Glasses ◽

Materials Science ◽

Configurational Entropy ◽

Mechanical Analysis ◽

Glass Transitions ◽

Solid State Physics ◽

High Entropy ◽

Sluggish Diffusion ◽

Mechanical Performances

AbstractGlass transition is one of the unresolved critical issues in solid-state physics and materials science, during which a viscous liquid is frozen into a solid or structurally arrested state. On account of the uniform arrested mechanism, the calorimetric glass transition temperature (Tg) always follows the same trend as the dynamical glass transition (or α-relaxation) temperature (Tα) determined by dynamic mechanical analysis (DMA). Here, we explored the correlations between the calorimetric and dynamical glass transitions of three prototypical high-entropy metallic glasses (HEMGs) systems. We found that the HEMGs present a depressed dynamical glass transition phenomenon, i.e., HEMGs with moderate calorimetric Tg represent the highest Tα and the maximum activation energy of α-relaxation. These decoupled glass transitions from thermal and mechanical measurements reveal the effect of high configurational entropy on the structure and dynamics of supercooled liquids and metallic glasses, which are associated with sluggish diffusion and decreased dynamic and spatial heterogeneities from high mixing entropy. The results have important implications in understanding the entropy effect on the structure and properties of metallic glasses for designing new materials with plenteous physical and mechanical performances.

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Filling of Mater-Bi with Nanoclays to Enhance the Biofilm Rigidity

Journal of Functional Biomaterials ◽

10.3390/jfb9040060 ◽

2018 ◽

Vol 9 (4) ◽

pp. 60 ◽

Cited By ~ 9

Author(s):

Giuseppe Cavallaro ◽

Giuseppe Lazzara ◽

Lorenzo Lisuzzo ◽

Stefana Milioto ◽

Filippo Parisi

Keyword(s):

Tensile Properties ◽

Food Packaging ◽

Mechanical Response ◽

Materials Science ◽

Traction Force ◽

Tensile Tests ◽

Mechanical Analysis ◽

Nanocomposite Films ◽

Preliminary Study ◽

Mechanical Performances

We investigated the efficacy of several nanoclays (halloysite, sepiolite and laponite) as nanofillers for Mater-Bi, which is a commercial bioplastic extensively used within food packaging applications. The preparation of Mater-Bi/nanoclay nanocomposite films was easily achieved by means of the solvent casting method from dichloroethane. The prepared bio-nanocomposites were characterized by dynamic mechanical analysis (DMA) in order to explore the effect of the addition of the nanoclays on the mechanical behavior of the Mater-Bi-based films. Tensile tests found that filling Mater-Bi with halloysite induced the most significant improvement of the mechanical performances under traction force, while DMA measurements under the oscillatory regime showed that the polymer glass transition was not affected by the addition of the nanoclay. The tensile properties of the Mater-Bi/halloysite nanotube (HNT) films were competitive compared to those of traditional petroleum plastics in terms of the elastic modulus and stress at the breaking point. Both the mechanical response to the temperature and the tensile properties make the bio-nanocomposites appropriate for food packaging and smart coating purposes. Here, we report a preliminary study of the development of sustainable hybrid materials that could be employed in numerous industrial and technological applications within materials science and pharmaceutics.

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Dynamic Mechanical Relaxation in LaCe-Based Metallic Glasses: Influence of the Chemical Composition

Metals ◽

10.3390/met9091013 ◽

2019 ◽

Vol 9 (9) ◽

pp. 1013 ◽

Cited By ~ 3

Author(s):

Minna Liu ◽

Jichao Qiao ◽

Qi Hao ◽

Yinghong Chen ◽

Yao Yao ◽

...

Keyword(s):

Glass Transition ◽

Transition Temperature ◽

Metallic Glasses ◽

Physical Aging ◽

Enthalpy Of Mixing ◽

Mechanical Analysis ◽

Mechanical Relaxation ◽

Atomic Mobility ◽

Dynamic Mechanical ◽

Β Relaxation

The mechanical relaxation behavior of the (La0.5Ce0.5)65Al10(CoxCu1−x)25 at% (x = 0, 0.2, 0.4, 0.6, and 0.8) metallic glasses was probed by dynamic mechanical analysis. The intensity of the secondary β relaxation increases along with the Co/Cu ratio, as has been reported in metallic glasses where the enthalpy of mixing for all pairs of atoms is negative. Furthermore, the intensity of the secondary β relaxation decreases after physical aging below the glass transition temperature, which is probably due to the reduction of the atomic mobility induced by physical aging.

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State-of-the-Art Diffusion Studies in the High Entropy Alloys

Metals ◽

10.3390/met10030347 ◽

2020 ◽

Vol 10 (3) ◽

pp. 347 ◽

Cited By ~ 6

Author(s):

Juliusz Dąbrowa ◽

Marek Danielewski

Keyword(s):

High Temperature ◽

Materials Science ◽

Driving Forces ◽

State Of The Art ◽

Point Of View ◽

High Entropy Alloys ◽

Diffusion Effect ◽

High Entropy ◽

Diffusion Studies ◽

Sluggish Diffusion

The development of the high entropy alloys (HEAs) is amongst the most important topics in the field of materials science during the last two decades. The concept of multicomponent, near-equimolar systems has been already applied to the number of other systems, including oxides, carbides, diborides, silicides, and it can be expected that other groups of materials will follow. One of the main driving forces for the development of HEAs is the so-called “four core effects”: high entropy effects, severe lattice distortion, cocktail effect, and sluggish diffusion effect. Their existence and extent has been a subject of heated discussion. Probably the least studied of them is the sluggish diffusion effect, which is of the, especially, high importance from the point of view of the most possible applications of HEAs—as high-temperature materials. Its alleged existence carries a promise of obtaining materials with superior mechanical properties, higher creep resistance, and less susceptibility to high-temperature corrosion. In the current review, the state-of-the-art of diffusion studies in HEAs was presented, as well as the resulting conclusions concerning the existence of the sluggish diffusion effect. Based on the literature analysis, it can be stated that there is no experimental evidence, which would support the existence of the sluggish diffusion in HEAs on the level of tracer and self-diffusivities. Nevertheless, it can be pointed out that our current state of knowledge on the diffusion in HEAs is still far from complete; therefore, further directions of studies are proposed.

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The Chemical Bond Across the Periodic Table: Part 1 – First Row and Simple Metals

10.26434/chemrxiv.11860941.v1 ◽

2020 ◽

Author(s):

Gabriel Freire Sanzovo Fernandes ◽

Leonardo dos Anjos Cunha ◽

Francisco Bolivar Correto Machado ◽

Luiz Ferrão

Keyword(s):

Physical Chemistry ◽

Chemical Bond ◽

Materials Science ◽

Chemical Elements ◽

Orbital Theory ◽

Solid State Physics ◽

Band Theory ◽

Van Der Waals Clusters ◽

Earth Systems ◽

Chemical Content

<p>Chemical bond plays a central role in the description of the physicochemical properties of molecules and solids and it is essential to several fields in science and engineering, governing the material’s mechanical, electrical, catalytic and optoelectronic properties, among others. Due to this indisputable importance, a proper description of chemical bond is needed, commonly obtained through solving the Schrödinger equation of the system with either molecular orbital theory (molecules) or band theory (solids). However, connecting these seemingly different concepts is not a straightforward task for students and there is a gap in the available textbooks concerning this subject. This work presents a chemical content to be added in the physical chemistry undergraduate courses, in which the framework of molecular orbitals was used to qualitatively explain the standard state of the chemical elements and some properties of the resulting material, such as gas or crystalline solids. Here in Part 1, we were able to show the transition from Van der Waals clusters to metal in alkali and alkaline earth systems. In Part 2 and 3 of this three-part work, the present framework is applied to main group elements and transition metals. The original content discussed here can be adapted and incorporated in undergraduate and graduate physical chemistry and/or materials science textbooks and also serves as a conceptual guide to subsequent disciplines such as quantum chemistry, quantum mechanics and solid-state physics.</p>

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Water-Tree Resistant Characteristics of Crosslinker-Modified-SiO2/XLPE Nanocomposites

Materials ◽

10.3390/ma14061398 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1398

Author(s):

Yong-Qi Zhang ◽

Xuan Wang ◽

Ping-Lan Yu ◽

Wei-Feng Sun

Keyword(s):

Electric Fields ◽

Tree Growth ◽

Mechanical Analysis ◽

Water Molecules ◽

Crosslinking Degree ◽

Water Tree ◽

Tree Resistance ◽

Alternating Electric Fields ◽

Trimethylolpropane Triacrylate ◽

Mechanical Performances

Trimethylolpropane triacrylate (TMPTA) as a photoactive crosslinker is grafted onto hydrophobic nanosilica surface through click chemical reactions of mercapto double bonds to prepare the functionalized nanoparticles (TMPTA-s-SiO2), which are used to develop TMPTA-s-SiO2/XLPE nanocomposites with improvements in mechanical strength and electrical resistance. The expedited aging experiments of water-tree growth are performed with a water-knife electrode and analyzed in consistence with the mechanical performances evaluated by means of dynamic thermo-mechanical analysis (DMA) and tensile stress–strain characteristics. Due to the dense cross-linking network of polyethylene molecular chains formed on the TMPTA-modified surfaces of SiO2 nanofillers, TMPTA-s-SiO2 nanofillers are chemically introduced into XLPE matrix to acquire higher crosslinking degree and connection strength in the amorphous regions between polyethylene lamellae, accounting for the higher water-tree resistance and ameliorated mechanical performances, compared with pure XLPE and neat-SiO2/XLPE nanocomposite. Hydrophilic TMPTA molecules grafted on the nano-SiO2 surface can inhibit the condensation of water molecules into water micro-beads at insulation defects, thus attenuating the damage of water micro-beads to polyethylene configurations under alternating electric fields and thus restricting water-tree growth in amorphous regions. The intensified interfaces between TMPTA-s-SiO2 nanofillers and XLPE matrix limit the segment motions of polyethylene molecular chains and resist the diffusion of water molecules in XLPE amorphous regions, which further contributes to the excellent water-tree resistance of TMPTA-s-SiO2/XLPE nanocomposites.

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High-Entropy Alloys for Advanced Nuclear Applications

Entropy ◽

10.3390/e23010098 ◽

2021 ◽

Vol 23 (1) ◽

pp. 98

Author(s):

Ed J. Pickering ◽

Alexander W. Carruthers ◽

Paul J. Barron ◽

Simon C. Middleburgh ◽

David E.J. Armstrong ◽

...

Keyword(s):

Austenitic Steels ◽

Irradiation Damage ◽

High Entropy Alloys ◽

Damage Resistance ◽

High Entropy ◽

Engineering Alloys ◽

Sluggish Diffusion ◽

Work Done ◽

Current Engineering ◽

Nuclear Applications

The expanded compositional freedom afforded by high-entropy alloys (HEAs) represents a unique opportunity for the design of alloys for advanced nuclear applications, in particular for applications where current engineering alloys fall short. This review assesses the work done to date in the field of HEAs for nuclear applications, provides critical insight into the conclusions drawn, and highlights possibilities and challenges for future study. It is found that our understanding of the irradiation responses of HEAs remains in its infancy, and much work is needed in order for our knowledge of any single HEA system to match our understanding of conventional alloys such as austenitic steels. A number of studies have suggested that HEAs possess `special’ irradiation damage resistance, although some of the proposed mechanisms, such as those based on sluggish diffusion and lattice distortion, remain somewhat unconvincing (certainly in terms of being universally applicable to all HEAs). Nevertheless, there may be some mechanisms and effects that are uniquely different in HEAs when compared to more conventional alloys, such as the effect that their poor thermal conductivities have on the displacement cascade. Furthermore, the opportunity to tune the compositions of HEAs over a large range to optimise particular irradiation responses could be very powerful, even if the design process remains challenging.

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Al, Cu and Zr Addition to High Entropy Alloys: The Effect on Recrystallization Temperature

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.1137 ◽

2018 ◽

Vol 941 ◽

pp. 1137-1142

Author(s):

Elena Colombini ◽

Andrea Garzoni ◽

Roberto Giovanardi ◽

Paolo Veronesi ◽

Angelo Casagrande

Keyword(s):

Solid Solution ◽

Grain Size ◽

Single Phase ◽

Boundary Energy ◽

Cold Deformation ◽

Recrystallization Temperature ◽

High Entropy Alloys ◽

High Entropy ◽

Ni Alloy ◽

Sluggish Diffusion

The equimolar Cr, Mn, Fe, Co and Ni alloy, first produced in 2004, was unexpectedly found to be single-phase. Consequently, a new concept of materials was developed: high entropy alloys (HEA) forming a single solid-solution with a near equiatomic composition of the constituting elements. In this study, an equimolar CoCrFeMnNi HEA was modified by the addition of 5 at% of either Al, Cu or Zr. The cold-rolled alloys were annealed for 30 minutes at high temperature to investigate the recrystallization kinetics. The evolution of the grain boundary and the grain size were investigated, from the as-cast to the recrystallized state. Results show that the recrystallized single phase FCC structures exhibits different twin grains density, grain size and recrystallization temperatures as a function of the at.% of modifier alloying elements added. In comparison to the equimolar CoCrFeMnNi, the addition of modifier elements increases significantly the recrystallization temperature after cold deformation. The sluggish diffusion (typical of HEA alloys), the presence of a solute in solid solution as well as the low twin boundary energy are responsible for the lower driving force for recrystallization.

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