Additiokovettuminen

Additiokovettuminen is a term used in materials science to describe the hardening of materials through additive processes or the deliberate introduction of second-phase particles during processing. The word combines additio (addition) with kovettuminen (hardening). It is not a single standardized process but a broad concept encompassing several methods that increase hardness by controlled additions of alloying elements or dispersed phases.

Its mechanisms include solid-solution strengthening from alloying elements, precipitation hardening where small particles form during aging and impede dislocation motion, and dispersion strengthening where fine particles hinder deformation. The relative contribution of each mechanism depends on the material system, particle size, distribution, and the heat-treatment or processing history.

Practically, additiokovettuminen can be pursued through alloy design, powder metallurgy, or additive manufacturing, followed by appropriate heat treatments. Methods include melting and alloying; mechanical alloying and dispersion of reinforcing particles; and post-processing steps that tailor particle distribution and the matrix microstructure. Process control aims to optimize factors such as temperature, time, and cooling rate to achieve the desired hardness.

Common material families considered for additiokovettuminen include steels, aluminum and titanium alloys, nickel-based superalloys, and certain ceramic-matrix composites. Potential applications span wear-resistant components, tooling, automotive and aerospace parts, and any domain where high hardness and retained strength are required at service temperatures.

Related concepts include solid-solution strengthening, precipitation hardening (age hardening), and dispersion strengthening. Additiokovettuminen is used primarily as a descriptive term in Finnish-language sources and is not universally adopted as a separate class of heat-treatment processes in English-language metallurgical literature.