Explanation

A compound formed by a transition metal M with a larger atomic radius and a non-metallic X (X=C, N, H, etc.) with a smaller atomic radius. The non-metallic atoms occupy the gap positions of the metal atomic structure. The formed compound does not conform to the valence principle. The interstitial phase can be divided into two types: when the atomic radius ratio rx/rM<0.59, interstitial phase with simple structure (such as face-centered cubic structure, hexagonal close packed structure, body-centered cubic structure) is formed; When rx/rM>0.59, most of them form interstitial phase with complex structure (such as orthogonal structure, complex cubic structure), which is customarily called interstitial compound. Most of the interstitial phase has obvious metal properties, and its hardness and melting point are high. It is a widely used alloy strengthening phase.

Classification