Formation of metastable structures in metalls and alloys

Formation and transformation of metastable alloys by ion irradiation are discussed on example of the systems Al-Fe, Ta(N), Ta(O), Fe-Cr. By ion beam mixing of Al-Fe multilayers with an overall composition of 60 to 85 at.% Al using 150 keV Fe ions metastable structures were formed. For 80 to 85 at% Al amorphous alloys have been observed. The formation amorphous interface regions cross-beam pulsed laser deposition (CBPLD) is demonstrated. Amorphus thin diffusion barriers of Ta were formed by ion implantation of nitrogen and oxygen. Fe-Cr thin layers with Cr concentration from 27 to 62 at.% Cr prepared by CBPLD show different metastable structures depending on the Cr content. These layers are paramagnetic at rom temperature. By ion irradiation it is possible to transform these alloys into a bcc structure with a ferromagnetion iron rich component.