What Is a Eutectic Point?

The eutectic point marks the intersection of the eutectic temperature and the eutectic composition. It is used to define the lowest temperature of solidification for a mixture of materials.

To determine the eutectic point, it requires an understanding of the eutectic temperature and the eutectic composition.

  • The eutectic temperature is the point at which a eutectic mixture freezes or melts
  • The eutectic composition defines the proportion of ingredients, known as constituents, in a mixture where the lowest possible complete melting point is defined

The mixture reaches the stage of eutectic composition only when the constituents have a uniform melting point as well as a uniform freezing point. Any other proportion of constituents does not yield a uniform freezing or melting point. At the eutectic point, the solid and liquid point of the mixture is the same.

Specifically, the point at which the solid and liquid temperatures are measured to be the same is the eutectic point. The eutectic system is known as an invariant reaction because there is thermal equilibrium. One of the most important factors in the eutectic system is how the components solidify within the system to form a singular macrostructure.

Some of the most familiar eutectic compositions include these items:

  • Solder
  • Cast iron
  • Silicon chips
  • Sodium chloride and water, when used for snow removal or ice cream making
  • Lidocaine