Abstract: The phase configuration of M2 high speed steel was studied by the Mossbauer effect in backscattering X-ray geometry. It was shown that the effect of substitutive alloy atoms in the near shell in the high speed steel on the effective ferromagnetic field can approximately be considered to be identical. So there are only four kinds of iron surroundirgs in mertensjte based on the alcove results, i.e., there are four kinds of iron surroungings corresponding to 0,1,2 and 3 substitutive alloy atoms in the nearest two shells respectively. The carbon atom in the retained austenite of M2 high speed steel is located at,the octahedral site and w ill segregate to the retained austenite phase during high temperature quenching.

Key words: Mossbauer effect in backscattering X-ray geometry, high speed Steel, phase configuration