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Glass Formation and Structural Modification in Glasses
Published in Abhay Kumar Singh, Tien-Chien Jen, Chalcogenide, 2021
Abhay Kumar Singh, Tien-Chien Jen
The SRM glass forming ability criterion can also be used for creating concrete glass formation by taking into account an additional factor that reflects specific conditions of glass formation. Usually the factor used is the cooling rate, which reflects the kinetic approach to the glass formation problem. As an example, comparing glass formation in telluride systems, it appears to be convenient to use the cooling rate of ≈ 180° Cs–1. According to several studies it is possible that glass formation in many systems at this temperate and substances quantity is sufficient for measurements and practical applications.
Freeze Drying
Published in Arun S. Mujumdar, Handbook of Industrial Drying, 2020
Athanasios I. Liapis, Roberto Bruttini
In practice, materials display one of two different types of freezing behavior: (a) the liquid phase suddenly solidifies (eutectic formation) at a temperature that depends on the nature of solids in the sample, or (b) the liquid phase does not solidify (glass formation), but rather it just becomes more and more viscous until it finally takes the form of a very stiff, highly viscous liquid. In case (b), there is no such thing as a eutectic temperature, but a minimum freezing temperature.
A new approach to design multicomponent metallic glasses using the mendeleev number
Published in Philosophical Magazine, 2022
Anurag Bajpai, Jatin Bhatt, Nilesh P. Gurao, Krishanu Biswas
Figure 1 shows the relation between the elemental attributes (r, , , ϕ and ) in binary combinations. The data has been linearly fit and R2 score for the binary correlation between the features is provided in the figure. The R2 values suggest that there is some, albeit weak, association among the attributes. Therefore, their combination can be employed as a single attribute to predict the properties of an element. From the scientific perspective, the chosen elemental attributes can explain glass forming characteristics of the multicomponent alloys from various viewpoints. Earlier studies by Inoue [30], Egami and Waseda [31] and Miracle [32] have emphasised the importance of topological consideration for designing MMGs by stabilising atomic clusters found in amorphous materials [33]. A large atomic size mismatch constrains the solubility of constituent elements in the competing crystalline phases as redistribution of atoms from liquid to solid is required during the crystallization process. The redistribution process can alter the composition and interfacial energy at the solid/liquid interface. This slows the nucleation process through structural influence and, as a result, can promote glass formation. Further, an adequate atomic size distribution can alter the cluster packing of the undercooled melts by improving their packing densities, lowering the ground-state energy, and stabilising the undercooled liquids, leading to an increase in GFA [31]. Moreover, a high internal strain originating from the difference in atomic size also destabilises the crystalline matrix [31]. Thus, the atomic size difference assessed in terms of the atomic radius of the constituent elements can be an essential feature in explaining the structural modalities in MMGs. According to the Hume–Rothery principles for solid solution formation, the electronegativity difference among alloy constituents reflects the bonding behaviour of atomic pairs [34]. An appropriate mismatch in electronegativity favours the formation of specific atomic pairs (or atomic clusters), which restricts the solubility among the constituent elements in the competing crystalline phases resulting in better glass-forming ability (GFA) [35].