AB-INITIO INVESTIGATIONS OF IRON-BASED MARTENSITIC SYSTEMS

We apply a full-potential first-principles method to investigate the e lectronic-structure and elastic features of pure iron and ordered tran sition metal systems like Fe-Ni and Fe-Mn. The martensitic phase trans formations in these compounds mainly depend on the properties of iron. Therefore the phase diagram of iron has been studied in detail in vie w of structural transformations and magnetic order. To this the total energy and magnetic moment have been investigated as function of the a tomic volume. In agreement with experimental results, we find a ferrom agnetic bcc ground-state and an antiferromagnetic fee phase having a h igher energy of 7 mRy. The resulting pressure for the bcc --> hcp tran sition is about 11.5 GPa in agreement with experiments. Besides that, total energy calculations have been done for stoichiometric Fe-Mn and Fe-Ni compounds. The resulting alloy phase diagrams are in a good agre ement with the experimental data.