Investigation of zirconium hydrides and hydrogen solubility limit in Zr-2. 5 Nb alloy by small angle neutron scattering

Journal Article · Tue Mar 01 00:00:00 EST 1994 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(94)90445-6· OSTI ID:5187428

Fong, R W.L. ^[1]; Spooner, S ^[2]

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1. AECL Research, Chalk River, Ontario (Canada). Reactor Materials Division
2. Oak Ridge National Lab., TN (United States)

In zirconium and its alloys, hydride phases form as needle-shaped ([gamma]-phase) or plate-shaped ([delta]-phase) precipitates when the terminal solid solubility (TSS) of hydrogen in the metal is exceeded. The hydrogen TSS in zirconium is almost negligible at room temperature, but at 620 K the solubility limit increases to about 1 at%. Zr-2.5 Nb alloy pressure tubes are the structural components in CANDU-PHW reactors and, if hydrides are present, the materials may be embrittled. A precise knowledge of the hydrogen TSS is required for assessing the fitness-for-service of Zr-2.5 Nb pressure tubes. However, in TSS measurements a hysteresis behavior is observed where the temperatures attributed to hydride dissolution and precipitation are different. This hysteresis occurs even in the absence of applied stress and may contribute to a variation in TSS values. To evaluate the feasibility of SANS for future experiments that will study zirconium hydride precipitation and dissolution, Zr-2.5 Nb samples containing several distributions of hydrides were tested at both room temperature and up to 600 K.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5187428
• Journal Information: Scripta Metallurgica et Materialia; (United States), Vol. 30:5; ISSN 0956-716X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
CANDU TYPE REACTORS
REACTOR MATERIALS
NIOBIUM ALLOYS
HYDROGEN EMBRITTLEMENT
ZIRCONIUM BASE ALLOYS
DISSOLUTION
MICROSTRUCTURE
PHASE STUDIES
PRECIPITATION
SOLUBILITY
ZIRCONIUM HYDRIDES
ALLOYS
EMBRITTLEMENT
HEAVY WATER MODERATED REACTORS
HYDRIDES
HYDROGEN COMPOUNDS
MATERIALS
PRESSURE TUBE REACTORS
REACTORS
SEPARATION PROCESSES
THERMAL REACTORS
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM ALLOYS
ZIRCONIUM COMPOUNDS
360103* - Metals & Alloys- Mechanical Properties
210400 - Power Reactors
Nonbreeding
Otherwise Moderated or Unmoderated