What is the Difference between Bulk Metallic Glass (BMG) and High Entropy Alloy (HEA) with respect to a specific parameters (no. of elements, Purity of constituting elements etc.). Also, Thermodynamically we can discuss.
Bulk Metallic Glasses (BMG) is a class of multi-component metallic materials, at which crystallization is kinetically suppressed by a number of factors like atomic diameter difference, high natural supercooling (due to near-eutectic composition), negative heat of constituent elements mixing, etc. Materials systems with high Glass-Forming Ability (GFA) a thermodynamically unstable, and then heating ("turning on" of diffusion) may cause their crystallization.
On the other hand, High Entropy Alloys (HEA) exist in single-phase solid solution crystalline state characterized by high configurational entropy. They just have a strong thermodynamically dictated tendency to avoid formation of ordered solid solutions as well as intermetallic compounds. The main term responsible for their stability is entropy term, so their heating improves their stability.
Number of elements in BMGs in not always 5 (and in HEAs should be 5 or more) and not in near equimolar quantities (HEAs are usually near equimolar), BMGs are amorphous and HEAs are crystalline. Both should be single phase BMGs amorphous HEAs solid solution.
Bulk Metallic Glasses (BMG) is a class of multi-component metallic materials, at which crystallization is kinetically suppressed by a number of factors like atomic diameter difference, high natural supercooling (due to near-eutectic composition), negative heat of constituent elements mixing, etc. Materials systems with high Glass-Forming Ability (GFA) a thermodynamically unstable, and then heating ("turning on" of diffusion) may cause their crystallization.
On the other hand, High Entropy Alloys (HEA) exist in single-phase solid solution crystalline state characterized by high configurational entropy. They just have a strong thermodynamically dictated tendency to avoid formation of ordered solid solutions as well as intermetallic compounds. The main term responsible for their stability is entropy term, so their heating improves their stability.
Alexander's answer is correct, just to stress, these are two different classes of materials and they do not share points in common, in BMG what you want is to avoid crystallization in bulk samples (hence the name), in the High Entropy Alloys what you want to do is to use the complex thermodynamics of very concentrated alloys to obtain unusual properties in crystalline samples (in fact, solid solutions). The attribution of these special properties to entropy is questionable, but these alloys are really interesting in the sense they combine high strength and high toughness.
In my opinion, the properties of the Bulk Metallic Glass (BMG) and High Entropy Alloy (HEA) are very similar, nevertheless, it is necessary to study this nuance experimentally.
High-entropy alloys (HEAs) are substances that are constructed with equal or nearly equal quantities of five or more metals. These alloys are currently the focus of significant attention in materials science and engineering because they have potentially desirable properties. These alloys are expected to have high configurational entropy and hence were termed as "high entropy alloys." HEAs have a broad range of structures and properties, and may find applications in structural, electrical, magnetic, high-temperature, wear-resistant, corrosion-resistant, and oxidation-resistant components.
Metallic glasses or amorphous metals are novel engineering alloys in which the structure is not crystalline (as it is in most metals) but rather is disordered, with the atoms occupying more-or-less random positions in the structure. metallic glass definition from en.m.wikipedia.org
An amorphous metal (also known as metallic glass or glassy metal) is a solid metallic material, usually an alloy, with disordered atomic-scale structure. Most metals are crystalline in their solid state, which means they have a highly ordered arrangement of atoms.
Regards
The so-called "entropy " doesn't exist at all.
During the process of deriving the so-called entropy, in fact, ΔQ/T can not be turned into dQ/T. That is, the so-called "entropy " doesn't exist at all.
The so-called entropy was such a concept that was derived by mistake in history.
It is well known that calculus has a definition,
any theory should follow the same principle of calculus; thermodynamics, of course, is no exception, for there's no other calculus at all, this is common sense.
Based on the definition of calculus, we know:
to the definite integral ∫T f(T)dQ, only when Q=F(T), ∫T f(T)dQ=∫T f(T)dF(T) is meaningful.
As long as Q is not a single-valued function of T, namely, Q=F( T, X, …), then,
∫T f(T)dQ=∫T f(T)dF(T, X, …) is meaningless.
1) Now, on the one hand, we all know that Q is not a single-valued function of T, this alone is enough to determine that the definite integral ∫T f(T)dQ=∫T 1/TdQ is meaningless.
2) On the other hand, In fact, Q=f(P, V, T), then
∫T 1/TdQ = ∫T 1/Tdf(T, V, P)= ∫T dF(T, V, P) is certainly meaningless. ( in ∫T , T is subscript ).
We know that dQ/T is used for the definite integral ∫T 1/TdQ, while ∫T 1/TdQ is meaningless, so, ΔQ/T can not be turned into dQ/T at all.
that is, the so-called "entropy " doesn't exist at all.
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