Fergana polytechnic insitute mechanical engineering faculty department of mechanical engineering and automation

with crystallization centers 
appear: atoms, molecules, and 
ions that are arranged in an orderly manner and tightly bound to each other. As a result 
of cooling, new ones appear next to them and occupy the entire volume of the 
substance. 
2. A rapid increase in the viscosity of the liquid with a decrease in 
temperature. 
It will be of 2 types: 
1) Crystallization does not occur at all: wax, wax, resin. These are called 
amorphous substances. 
2) Before crystallization begins, the substance q is released, because the rate of 
increase in cohesion is much greater than the rate of crystallization, so it does not have 
time to crystallize. These are called glassy substances. 
The molecules 
oscillate in the lattice: but the mutual bond force holds them 
together. To leave the surface of the crystal and go to the liquid state, it is necessary to 
get a certain amount of thermal energy. In the liquid phase, the energy per unit volume 
of the substance at the melting temperature is greater than in the crystalline phase. 

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The difference in these 
internal energies is 
equal to 
the relative melting 
temperature. 
On the contrary, that is, crystallization begins only after the above energy leaves 
the "liquid phase-crystal" system. 
the substance increases , the molecules come closer together, the strength of the 
bond increases and it provides "hardness". There are also misconceptions. Water, 
bismuth, and antimony expand when q ot g : that means the molecules move away. 
Therefore, the decisive factor in the firing process is the limitation of the freedom 
of thermal movement of the particles . This limitation is expressed by the increase in 
the strength of mutual binding of particles, which appears after they are arranged in a 
crystal.