Microstructure and Phase Control in Zr-Fe-Cr-Ni Alloys: Thermodynamic and Kinetic Aspects

摘要

TEM investigations in Zr-Fe and Zr-Fe-Ni, Zr-Ni-Cr and Zr-Cr-Fe systems were performed to assess the second particles present in these alloys, either in quasi equilibrium conditions, or after quenching and annealing experiments. At equilibrium, Zr_3Fe was found to dissolve Ni up to 12 at%. Ab initio computations provided formation enthalpies for several Zr-Fe compounds and showed that the Zr_2Fe is metastable at low temperature. All of these data allowed us to extend the thermodynamic database ZIRCOBASE; very good agreement between the thermodynamic computations and the experimental evidences was obtained. Quenching and annealing experiments showed that Zr_2Fe is formed for low quenching rates, while Zr_3Fe is formed for higher quenching rates. Last, corrosion results in various conditions show that the influence of second phase particles volume fraction depends on the corroding atmosphere.