Einschlusskerne

Einschlusskerne are a phenomenon observed in certain solidification processes, particularly in metals and alloys. The term, which translates from German to "inclusion nuclei," refers to microscopic solid particles that act as preferential sites for the nucleation and growth of new solid phases during melting or solidification. These inclusions can be metallic, oxide, nitride, or carbide in nature.

The presence of einschlusskerne significantly influences the microstructure of the solidified material. By providing a substrate for heterogeneous nucleation, they can promote the formation of a finer grain structure compared to homogeneous nucleation, which occurs spontaneously within the liquid. This finer grain size often leads to improved mechanical properties such as increased strength and toughness.

However, einschlusskerne can also be detrimental. If these particles are non-metallic and brittle, they can act as stress concentrators, leading to premature fracture. The size, distribution, and chemical composition of the einschlusskerne are critical factors determining their effect. In some applications, controlled addition of specific einschlusskerne, known as inoculants, is used to manipulate the solidification process and achieve desired microstructural characteristics. Conversely, in applications where purity is paramount, minimizing or eliminating unwanted einschlusskerne is a primary concern. The study and control of einschlusskerne are therefore important aspects of materials science and engineering.