ISSN:
1573-8205
Source:
Springer Online Journal Archives 1860-2000
Topics:
Energy, Environment Protection, Nuclear Power Engineering
,
Physics
Notes:
Abstract Metallographical examination, thermal analysis and electrical resistance measurements have been applied to a study of the zirconium apex, up to 82% zirconium and a temperature of 1200 °C, of the ternary system Zr-Ta-Nb, with limited solubility of tantalum and niobium in α-zirconium (γ phase), limited solubility and complete solubility of niobium in ß-zirconium, with eutectoid decomposition of the ß solid solution and three-phase eutectoid equilibrium ß ⇌ α + γ between α- and ß-zirconium. In the investigated portion of the Zr-Ta-Nb phase diagram, the following phase regions were found: a) two one-phase regions α and ß; b) three two-phase regions α + ß, ß + γ and α + γ: c) one three-phase region α + ß + γ; the ß region contracts as the temperature falls below 1200 ° C. The solubility of tantalum and niobium inα-zirconium in the system Zr-Ta-Nb is about 0.5%. On passing from Zr-Ta to Zr-Nb, the α + ß and ß + γ regions are displaced toward lower temperature and high niobium concentrations; the boundaries of the α + γ and α + ß + γ regions are lowered from 790 ° for Zr-Ta to 612 °C for Zr-Nb. Passing between the α + ß and ß + γ regions is a binary eutectoid line which, from Zr-Ta to Zr-Nb is displaced toward lower temperatures and higher niobium conentrations. The solubility of niobium in α zirconium in the Zr-Nb system is about 0.5% by weight. Eutectoid decomposition in the Zr-Ta system shifts the maximum of the martensltic-like transformation to the left and results in an increase in the stability of the ß phase at room temperature In quenched alloys.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01587180
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