High-Temperature Isothermal Nucleation of the Metastable Omega Phase in Zr-Nb Alloys

AURELIO, G.; A. FERNÁNDEZ GUILLERMET; P. B. BOZZANO; CUELLO, G. J.

Krakow, Polonia

Conferencia; CALPHAD 2004; 2004

This paper presents an experimental study and an analysis of the isothermal nucleation of themetastable omega (§Ù) phase in a high-Nb Zr-Nb alloy. The work combines in situ neutron thermodiffraction (NTD) with transmission electron microscopy (TEM) observations at room temperature in quenched/aged/quenched alloys. The NTD data are interpreted on the basis of a rather general lattice parameter vs. composition systematics established very recently by us. The results of the present study lend strong support to a picture of the isothermal bcc¡æ §Ù phase transformation which involves the initial formation of significantly Nb-depleted §Ù nucleii.