Ural Federal University: Physicists Identify New Properties of Matter Solidification
Physicists at Ural Federal University have identified a new law that accounts for the anomalous behavior of melts. Using a mathematical model, scientists have explained these deviations, whose causes were previously unclear. This, in turn, will help create a new generation of materials, melts with given properties. Description of the model published in Scientific Reports (Nature Publishing Group). The research was supported by the Russian Science Foundation (grant 21-79-10012).
“It used to be assumed that the rate of solidification of melts increased with increasing temperature. However, this is not systematically true. In some cases, for example due to impurities or alloy features, abnormal behavior can be observed. We managed to explain this phenomenon – we came to the conclusion that it is necessary to take into account the nucleation of crystals inside the two-phase zone, which reduces the supercooling of the melt, makes this layer narrower and slows the rate of movement of the crystallization front. We derived a law that takes into account this anomalous behavior,” explains Lyubov Toropova, a senior researcher at the Laboratory of Mathematical Modeling of Physical and Chemical Processes at UrFU.
As physicists have found out, this anomalous behavior is explained by nucleation: the rate of solidification drops when crystals are nucleated and begins to grow in cases where crystals have nucleated and continue to grow.
The new model was tested on aluminum-nickel alloy. A series of experiments were conducted by German colleagues in the laboratory using an electromagnetic levitator and on board an aerospace station at the Cologne Science Center. The data confirmed the theoretical calculations.
“Our model takes into account the movement of the interface between the solid and liquid phases, taking into account the nucleation and growth of crystals. No one has done this before. The calculations are universal and will be useful for specialists in the aerospace industry, for obtaining materials with specified properties, for predicting the properties of alloys, for forming new high-strength structures applicable in new generations of materials,” explains Dmitry Alexandrov, a leading researcher at UrFU Laboratory of Multi-Scale Mathematical Modeling.