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Metallic glasses constitute a class of engineering materials having an enormous potential for many fields of application due to their superior properties. Here, we report on a new family of sulfur-bearing bulk metallic glasses. So far, sulfur was not considered as alloying element for the synthesis of bulk metallic glasses. We observe bulk glass formation in a variety of sulfur-containing systems, including titanium-based bulk glass-forming systems with an extremely high titanium content of 70 at.%. These findings allow the development of a whole new class of amorphous metals, having good processability and consisting of alloying elements suitable for industrial applications.

The paper studies the effect of carbon-containing materials (graphite, shungite carbon and acetylene soot) on the properties of composites and coatings based on the Si‒ B4C‒ZrB2 glass-forming system. Thermogravimetric and differential thermal analyzes, thermal resistance tests were carried out, the phase composition was determined, and the surface morphology of the coatings was also studied. It is shown that with the introduction of carbon additives, the area of the vitrified surface of the coating increases, in connection with this, the resistance of the material to high temperatures and other aggressive media improves.

The connection between slow activated relaxation in glass-forming liquids and various equilibrium thermodynamic properties remains intensely debated. The microscopic elastically collective nonlinea...

We investigate the heterogeneity of dynamics, the breakdown of the Stokes-Einstein relation and fragility in a model glass forming liquid, a binary mixture of soft spheres with a harmonic interaction potential, for spatial dimensions from 3 to 8. Dynamical heterogeneity is quantified through the dynamical susceptibility $\chi_4$, and the non-Gaussian parameter $\alpha_2$. We find that the fragility, the degree of breakdown of the Stokes-Einstein relation, as well as heterogeneity of dynamics, decrease with increasing spatial dimensionality. We briefly describe the dependence of fragility on density, and use it to resolve an apparent inconsistency with previous results.

Development of advanced metals materials with ultrahigh strength, large plasticity and high thermostability is one of the most attractive aims for materials researchers. Co-based bulk metallic glasses (BMGs) with the highest strength (up to 6 GPa) and special strength (up to 650 Nm/g) among all of metals materials so far we known have received extensive attentions. In this paper, a family of Co-Ta-B-Si BMGs with high glass-transition temperature (above 870 K), large compressive plasticity (up to 6.4 %) and high strength (above 5.5 GPa), and high glass-forming ability (the critical diameter, Dc: up to 4 mm) was developed by accurately tuning metalloid element contents of Si and B in the parental alloy of Co55Ta10B35. The changes of glass formation and plasticity caused by the adjustment of the constituent metalloid elements were evaluated by the combination of experimental and calculated results. The reason for the significant improvement of plastic deformation is revealed by the analysis of the self-organization behaviors of high-density shear bands.

In the present study, we show that the range of the temperature ratio TA/Tg for fragile glass-forming liquids is predicted by adopting TA ~ Tx, where TA is the temperature that the Arrhenius crossover appears and Tx is the cooperativity onset temperature extracted from the Bond Strength–Coordination Number Fluctuation model proposed by the authors. Specifically, when the above relation is used in conjunction with the two-thirds rule (Tg/Tm = 2/3) and the empirical criterion for good glass-formers (TA/Tm $$ \gtrsim $$ 1.0), the predicted range of the Arrhenius crossover is calculated to be 1.5 $$ \lesssim $$ TA/Tg < 2.1. This range is in good agreement with the values confirmed in fragile systems, encompassing a wide range of glass-forming materials, excepting the network systems.

A series of new cyclic siloxane side-chain liquid crystal oligomers containing chiral (-)-menthyl monomer (M1) and achiral benzene methyl ester monomer (M2), denoted as O1–O4, were successfully syn...

Despite decades of intensive rehearses, we still lack robust and physically clear methods to discover new metallic alloys with high glass-forming ability (GFA). Different empirical criteria propose...

Micron-scale powdered amorphous soft magnetic materials are highly pursued for miniaturised and high-efficiency power inductors working at high frequencies due to their excellent soft magnetic prop...

It is a long-standing challenge to search for metallic glasses (MGs) with optimal combinations of glass-forming ability (GFA), strength and toughness in the vast compositional space. By taking into account both recently developed ellipse criterion and temperature-based GFA criterion, here we established quantitative correlations among compositions, elastic constants, GFA and mechanical properties of MGs, which enable to predict the GFA, fracture strength and fracture surface simultaneously in advance once the compositions of MGs are determined. Experimental data confirm the validity of this approach in prediction. Finally, a strategy for designing MGs with optimal combinations of strength, toughness and GFA is proposed, which allows for high-throughput discovering glass formers with excellent mechanical properties.

In this study, the glass-forming ability (GFA) of the Hf-Cu-Ni system has been evaluated by a kinetic approach. The viscosity of individual elements was used in the present analysis. These viscosity values are further utilized to plot the time-temperature-transformation (TTT) curve and to determine the critical cooling rate (Rc). It has been observed that with a decrease in Hf content, the TTT curve shifts to the right, suggesting an enhancement in the GFA. These findings are consistent with the reported literature.

The thermal and magnetic properties of the ternary Fe-B-C and quaternary Fe-B-C-Si amorphous alloys have been investigated. It has been discovered that the ternary Fe-B-C amorphous alloys with compositions close to Fe79.3B14.3C6.4 exhibit a glass transition prior to crystallization on heating. The alloys also have high mass magnetization of 176–178 A m2/kg at room temperature. In addition, the glass-forming ability (GFA) of the alloys is significantly enhanced by the addition of 4 at% Si while maintaining high magnetization of approximately 170 A m2/kg at room temperature. In was found that the Fe23(B, C)6 phase (Cr23C6-type) is formed during crystallization of the quaternary Fe-B-C-Si alloys with the large GFA. It was also confirmed that the amorphous powders of Fe-Cr-B-C-Si alloys could be produced by a conventional water atomization method and exhibit the low core losses of 305–362 kW/m3 at 100 kHz and 100 mT. The quaternary Fe-B-C-Si amorphous alloys with high GFA, high magnetization and low core losses are suitable for a core material of various magnetic components.

Developing materials with excellent properties has been the untiring pursuit of mankind. Metallic glasses (MGs) would be the ideal metallic materials if their size could be scaled up to be comparable to traditional metals. To address this challenge, a variety of approaches have been attempted over the past decades, including thermodynamics-based alloy, 3D printing and the recent artificial intelligence-guided optimal alloy. In this study, a facile and flexible route was demonstrated to manufacture giant MGs (GMGs) with diameters more than 100 mm through the thermo-joining process. The jointed GMG samples feature almost the same performance as the as-cast ones. The ability of manufacturing complex 3D components such as the Chinese Zodiacs was also demonstrated. Our approach might overcome the longstanding problem of glass forming ability (GFA) limitations in alloy systems and pave new concept and route to fabricate size unlimited MGs.

Classical molecular dynamics study of metallic glass-forming alloys, Zr36Cu64 and Zr47Cu46Al7, is carried out to acquire atomic level understanding of the microalloying effect of Al atoms on the structure and dynamics of the alloy. The results indicate that in comparison to hard sphere-like atomic packing in the binary alloy, microalloying of Al brings in a fundamental modification in the atomic packing due to soft sphere-like Cu-Al bonding due to chemical short-range ordering (CSRO). In the ternary alloy, CSRO is found to homogenize the topological packing of the icosahedra ( ). Microalloying also impacts the single particle dynamics at the timescale of β-relaxation and could have important implications on the mechanical properties of the glasses prepared from this alloy.

Ribbons having the chemical composition Cu48Zr47Al5 and Cu45Zr45Al5Ag5 were made using the melt spinning technique in an open environment. Making a product, in this case glassy ribbons, on a large scale is fitting if the process and materials are not costly hence controlled atmosphere was not used for the melt spinning technique. In this paper such a trial was done to check how adding Al and Al-Ag changes the structural and mechanical properties of Cu-Zr alloys. The structure, GFA (glass forming ability) and hardness were analyzed using X-ray diffraction, differential scanning calorimetry, Vickers-type hardness. Also, the GFA was estimated with the help of a series of different parameters (e.g., supercooled liquid region).

Excess entropy and mismatch entropy in CuxZr100-x (46 ≤ x ≤ 70) and Cu50Zr50-xAlx (5 ≤ x ≤ 40) alloys have been obtained using an analytical thermodynamic approach based on hard-sphere model for the structure of liquids. The atomic packing efficiency is an important input parameter in this approach and is usually taken to be 0.64 for all the metallic systems. In this study, classical molecular dynamics simulations have been performed to obtain the packing efficiency by analyzing the three-dimensional microscopic structure of metallic alloys. The compositional dependence of the entropies in Cu-Zr alloys show a good correlation with the glass-forming ability and, it is consistent with the experimental and simulation results. For Cu-Zr-Al alloys, the variation in the entropies with the composition does not indicate an unambiguous correlation with glass-forming ability. However, these results provide useful insights of the effect of substitution of Zr by Al on the glass-forming ability.

We employ a new force-level statistical mechanical theory to predict spatial gradients of the structural relaxation time and Tg of polymer liquids near microscopically rough and smooth hard surface...

In this article we show that inverse free volume is a natural variable for analyzing relaxation data on glass-forming liquids, and that systems obey the general form, log(τ/τref) = (1/Vfree) × f(T), where f(T) is a function of temperature. We demonstrate for eight glass-forming liquids that when experimental relaxation times (log τ), captured over a broad pressure–volume–temperature (PVT) space, are plotted as a function of inverse free volume (1/Vfree), a fan-like set of straight line isotherms with T-dependent slopes ensues. The free volume is predicted independently of the dynamic results for each state point using PVT data and the Locally Correlated Lattice (LCL) equation of state. Taking f(T) ∝ 1/Tb, we show that, for each of the systems studied, only the single, system-dependent parameter, b, is required to collapse the fan of linear isotherms into a straight line. We conclude that log τ is a function of the combined variable, 1/(VfreeTb), and because it is linear, it allows us to write an explicit ...

La- and Nb-doped BaTi2O5 (BT2) spherical glasses were prepared by a containerless aerodynamic levitation method and their glass-forming regions were established. It is found that La-doping on the Ba-site (network-modifier) and Nb-doping on the Ti-site (network-former) show distinct difference in the glass-forming region: less than 10 % La can replace Ba whereas 40 % Nb can incorporate into BT2 glass. The distinction in glass-forming ability induced by La- and Nb-doping is discussed mainly from the structural arrangement of the glass. Raman spectroscopy analysis shows that La-doping elongates the short Ti–O bonds in the distorted [TiO5] polyhedra and thus relaxes the network. Nb-doping introduces [NbO6] polyhedra into BT2 and there exists a critical doping level (20 %), below which incorporation of Nb into BT2 relaxes the [TiOn] polyhedra by shortening the long Ti–O bond and above which [NbO6] starts to participate in the network skeleton construction resulting in a dramatic change in the glass structure, which is supported by the dramatic change in the exothermic peak on the DTA curves. This work triggers the speculation that the network-modifiers in BT2 glass possess a very important role in the structure of network-former skeleton than those in glasses based on traditional network-former oxides such as SiO2, GeO2 and B2O3, which may provide a useful strategy for modifying the properties of these novel glasses by chemical doping.

The high entropy effect is often insufficient to fully stabilize single-phase solid solutions (SPSS), yielding only few, mostly metastable SPSS. While the prospective space of favorable SPSS formation is smaller than commonly assumed, larger degrees of metastability can open up the vast High Entropy Alloy space. We argue that HEAs form metastable SPSS through polymorphic solidification upon rapid cooling. To quantify a HEA's metastability, we propose the critical cooling rate of SPSS formation RCSPSS, analogous to RCGlass. Thereby, we can compare multicomponent alloys by their metastability and SPSS or glass forming ability, which is determined by their underlying atomic dispersity.

The generalized entropy theory (GET) of glass formation provides an analytic framework for the structural relaxation time and thermodynamic properties of glass-forming polymers in terms of molecula...

Motivated by empirical observations suggesting that changes in the activation volume ΔV# upon varying temperature (T), determined from the pressure (P) dependence of the segmental structural relaxa...

In this paper, the effect of the replacement of Fe by Nb on the glass forming ability (GFA), the thermal stability and the crystallization behavior of Fe84.5−xSi0.5B10.5P3.5C0.7C0.3Nbx (x = 0, 1, 2) alloys were investigated. The results show that the addition of Nb increases the GFA. Increasing Nb content can enhance the first onset crystallization temperature (Tx1), the second onset crystallization temperature (Tx2) and ΔTx (ΔTx = Tx2 − Tx1), which broadens the range of annealing temperatures. The coercivity (Hc) of ribbons decreases with increasing Nb content after annealing at a low heating rate and reach as a minimum of 24.5 A/m when the Nb content is 2 at.%. The process of annealing at a high heating rate distinctly decreases Hc, and all samples present excellent soft magnetic properties. The nanocrystalline alloy exhibits the lowest Hc of 6.4 A/m after annealing at 460 °C for 5 min.