Samples obtained from the hot conditioning and hot performance procedu
res have been investigated by GEMS. Various types of substrates were c
onsidered. The surface phases were assigned to magnetite, alpha-Fe, wu
stite and to spinel solid solutions. The data have been analyzed takin
g into account the compound stoichiometry, the number of iron unequiva
lent positions appeared in each identified phase and the relative rati
o of the formed products.