Accurate quantitative EDS-TEM analysis of precipitates and matrix in equilibrium (α+β) Zr–1Nb alloys with Ta addition

Abstract

The (α+β) phase microstructure in Zr-1.05Nb, Zr-0.85Nb-0.20Ta and Zr-0.85Nb-0.40Ta (wt.%) alloys annealed at 570 °C for 3840 h after β-quenching were observed at different scales by optical, SEM and TEM microscopies. A quantitative study of phase chemical compositions was carried out by EDS-TEM with experimental Cliff-Lorimer factors. The α matrix was measured on thin films and the β particle on carbon extractive replicas. The Ta addition showed a continuous increase of (Nb + Ta) solubility in α-Zr and (Zr + Ta) solubility in the β-Nb phase. The increase of Ta in the nominal composition of the Zr-1(Nb, Ta) alloy causes the decrease of the mass fraction of β-Nb phase.