SURFACE SEGREGATION PHENOMENA ON FE-3.5-PERCENT-MO-N(100) - THE FORMATION OF A MON SURFACE COMPOUND

Molybdenum and nitrogen cosegregation is investigated on (100) oriente d surfaces of Fe-3.5%Mo-N single crystals applying Auger electron spec troscopy (AES) and low energy electron diffraction (LEED). The formati on of a two-dimensional MoN surface compound occurs at temperatures ra nging from 500 to 790 degrees C. Ar+ ion depth profiling indicates tha t the MoN consists of approximately two compound layers. Within the AE S detection limit the existence of three-dimensional MoN surface preci pitates is ruled out. The MoN-covered substrate surface exhibits a sha rp (1x1) LEED pattern indicating the epitaxial stabilization of the Mo N surface compound on the bcc (100) surface.