intermetalliska

Intermetalliska, or intermetallics, are compounds formed between two or more metals that have a fixed chemical formula and an ordered crystal structure. Unlike solid solutions, their composition is definite, and the arrangement of atoms confers properties that are distinct from those of their constituent elements.

Common classes include aluminides (such as Ni3Al and TiAl), silicides (e.g., Mg2Si), and various borides and Heusler-type compounds. Intermetallics may be binary or more complex, and often exhibit high melting points and unusual combinations of stiffness, density, and corrosion resistance.

A key characteristic is brittleness at room temperature, which limits ductility and toughness. They often display good high-temperature strength and oxidation resistance, but low fracture toughness. Processing challenges arise from poor forgeability and sensitivity to microstructure, requiring specialized heat treatments and controlled solidification.

Formation and processing involve diffusion-controlled reactions, powder metallurgy, diffusion bonding, or reactive synthesis from elemental powders. Microstructure control (grain size, phase distribution) is crucial for performance. Techniques such as hot isostatic pressing and directional solidification are used to improve properties.

Applications include TiAl-based alloys for lightweight, high-temperature turbine components, Ni3Al coatings and components for oxidation resistance, and FeAl/Fe3Al alloys for corrosion resistance. Some intermetallics are important in electronics and magnetic materials.

Ongoing research seeks to expand ductility and weldability, explore novel compositions, and tailor microstructures to combine high-temperature performance with manageable processing, broadening their use in aerospace, energy, and industrial components.