SYMPOSIA PAPER Published: 01 January 1989

Intermetallic Precipitates in Zirconium-Niobium Alloys


Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) have Seen used to study the composition and structure of intermetallic precipitates, principally those containing iron and chromium, in Zr-2.5wt%Nb pressure tubing and Zr-lwt%Nb fuel sheathing. The Zr-lwt%Nb fuel sheathing contained Zr(FeCr)2 Laves phase precipitates with either the C-14 hexagonal or C-15 cubic structure. Orthorhombic Zr3Fe precipitates were also tentatively identified. Tetragonal Zr2Fe precipitates were found in Zr-2.5wt%Nb pressure tubing containing 700-ppm iron. The volume fraction of Zr2Fe was very small (<0.1% on an area basis) and was much smaller than the volume fraction of Zr(FeCr)2 precipitates in Zr-1wt%Nb.

The difference in type and volume fraction of iron-containing precipitates in Zr-lwt%Nb and Zr-2.5wt%Nb despite similar iron and chromium contents is tentatively attributed to the different volume fractions of the β-phase. Iron is a β-stabilizer and concentrates in the β-phase. The Zr-2.5wt%Nb alloy, which contains the higher volume fraction of β-phase, takes in more iron in solution in the β-phase thus leaving less to precipitate out as an intermetallic.

Author Information

Meng, X
University of Windsor, Windsor, Ontario, Canada
Northwood, DO
University of Windsor, Windsor, Ontario, Canada
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Developed by Committee: B10
Pages: 478–486
DOI: 10.1520/STP18882S
ISBN-EB: 978-0-8031-5084-3
ISBN-13: 978-0-8031-1199-8