| Popis: |
We have investigated ion-induced atomic mixing process as an alternative approach to conventional rapid quenching techniques for producing thin film metastable alloys. Multi-layered samples consisting of thin alternate layers of two elements were bombarded with energetic Xe ions. Formation of metastable phases such as supersaturated solid solutions and amorphous alloys were obtained as a result of atomic mixing. The systems under investigation are binary couples of Au and one of the fourth-period transition metals, Ni, Co, Fe or V. For samples irradiated at R.T., metastable crystalline phases were usually formed. In the AuNi and AuCo systems, single-phase f.c.c. solid solutions over an entire range of composition have been produced. In the AuFe and AuV systems, the Au-rich alloys showed a f.c.c. structure while the Fe (or V)-rich alloys showed a b.c.c. structure. The simultaneous presence of a f.c.c. phase and a b.c.c. phase was found in alloys with compositions Au38Fe62 and Au40V60. For samples irradiated at LN2 temperature, the structures of the alloys were found to be more random in nature. Amorphous phases of compositions Au25Co75 and Au40V60 were obtained. Comparisons of results observed on various systems indicate that the formation and structure of metastable phases are strongly influenced by the equilibrium nature of the system. |
