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Anonymous users2024-02-13A substance in one state may have several different phases. The gaseous state of a substance has only one phase because after the mixing of multiple gas phases, there is no clear boundary between the various components that can be distinguished. The liquid state of a substance generally has only one phase, and several different liquids can only form one phase if they can be mixed evenly.
It is only when two liquids cannot be mixed (e.g. water and oil) that a split interface occurs, forming two phases. For solids, different crystal lattice structures correspond to different physical properties, so the same solid can have different phases, from which it can also be seen that the differences in states and phases in physical sense. Iron has four phases, y, y, and δ.
Ice has seven phases, numbered with Roman numerals, of which, phase is an unstable phase.
The process by which a solid changes from one phase to another is known as allotrope transition. This phase transition is of great practical significance for metallurgy. Steel is the product of pure iron doped with carbon, and the iron atoms of austenitic steel are arranged into a face-centered cubic lattice, and the carbon atoms are located in the lattice gap in the form of gap-filling.
When austenitic steels are heated to high temperatures and then slowly lowered, austenitic steels are transformed into less carbon-rich ferrite (which has a body-centered cubic lattice structure).
The excess carbon is precipitated in the form of cementite. However, when the lattice structure of iron is rapidly cooled to room temperature by heat treatment, although the lattice structure of iron changes from a face-centered cube to a body-centered cube, the excess carbon atoms cannot be precipitated from the iron due to the difficulty of diffusion. Martensitic steel is much harder than austenitic steel and can be used as a cutting tool.
Phase transitions are a very common physical phenomenon. When some rod-shaped polymer materials change from solid to liquid, some intermediate phase liquid crystals are formed in the middle, and liquid crystals also have several different phases. At a low temperature of 2 17 Ke, liquid helium will produce some special properties, such as superfluidity, which is also a phase transition, which belongs to the second phase transition.
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Anonymous users2024-02-12In the solid-state phase transition, the interface between the new phase and the parent phase is the interface of two crystals, which can be divided into coherent interface, semi-coherent interface and non-coherent interface according to the structural characteristics.
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Anonymous users2024-02-11A phase change material (PCM) is a substance that changes the state of matter and provides latent heat at a constant temperature. The most common PCM is water, which changes from a liquid state to a solid state (freezing) at temperatures as low as 0°C. When the temperature is above 0°C, the water changes from a solid state to a liquid state (dissolved).
A large amount of cold energy is inhaled and stored during the icing process, while a large amount of heat energy is absorbed during dissolution.
PCMs can be divided into organic and inorganic PCMs. It can also be divided into hydrated salts and paraffin wax.
The biggest difference between organic and inorganic PCMs is the difference in durability and fire resistance when applied to building materials, and the latter is better than the former.
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Anonymous users2024-02-10Solid-state phase transition is a discipline that studies the formation and stability of various solid microstructures.
When a group of atoms or molecules has a homogeneous atomic or electronic configuration, the aggregate is called phase. It has a range of thermodynamic properties, such as volume, pressure, temperature, and energy. There is a clear boundary between the two phases, and the microstructure, composition (or both) on both sides of the phase boundary changes discontinuously.
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Anonymous users2024-02-09Solid-state phase transitions study the microstructure of various solids.
and its stability.
When an aggregate of a group of atoms or molecules has a homogeneous atomic or electronic configuration, the aggregate is called a phase; It has a range of thermodynamics.
Properties such as volume, pressure, temperature, and energy.
A phase transition is a discontinuous change in the microstructure, composition (or both) of two phases with a clear boundary between two phases.
There are different classifications according to different classification methods, taking the solid phase transformation of metals as an example:
By the equilibrium state of the phase transition.
It can be divided into equilibrium phase transition and non-equilibrium phase transition;
Classified by thermodynamics.
It can be divided into first-order phase transformation and second-order phase transformation;
Classification by migration characteristics of atoms.
It can be divided into diffusion phase change and non-diffusion phase change.
It is due to the fact that the earth revolves around the sun, the moon revolves around the earth, and at the same time, the moon revolves around the sun along with the earth. And when the moon is located between the earth and the sun on the first day of each lunar month, facing the earth with a dark side, and haunts the sun almost at the same time, so it cannot be seen on the ground, this is the new moon, also called "Shuo", and the moon continues to rotate forward until the beginning of the lunar calendar. >>>More
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The first question, I think that if the earth and the sun are close enough, there should be no day and night, because even refraction is enough to make the earth bright, of course, the four seasons are gone, the surface of the earth will be tens of thousands of high temperatures, how can there be four seasons, and about the moon's roundness, I think that under such a strong light, if people can really survive, the naked eye will not be able to see the moon >>>More