Hydrogen embrittlement in single- and poly-crystal niobium

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1980

OSTI ID:5533950

Farahani, M M

The effect of dissolved hydrogen on the yielding and the ductility of, both poly- and single-crystal, niobium have been studied in the temperature range between 78 and 373 K. Tensile tests were carried out on niobium specimens containing hydrogen ranging between 30 and 230 ppM wt, at a strain rate of 1.7 x 10/sup -4/ sec/sup -1/. The fracture surfaces of specimens tested were also examined by means of a scanning electron microscope (S.E.M.). These studies were undertaken with the ultimate goal of determining the roles of hydrogen concentration, grain boundaries, and temperature in the embrittlement and fracture process of a representative of group VA metals. The results obtained show that the addition of 30, 80, and 130 ppM wt H has no significant effect on the yield stress of either single- or poly-crystal niobium over the entire range of temperature studied. Addition of 230 ppM wt H to single crystal niobium, however, is found to have a strengthening effect in the temperature range where hydrogen is in solid solution. At lower temperatures, where the hydride phase is to be formed, no increase in the yield stress by hydrogen is observed. The addition of hydrogen strongly influences the temperature dependence of ductility of niobium.

• OSTI ID: 5533950
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
CRYSTAL STRUCTURE
CRYSTALS
DUCTILITY
ELECTRON MICROSCOPY
ELEMENTS
EMBRITTLEMENT
FRACTURE PROPERTIES
GRAIN BOUNDARIES
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN EMBRITTLEMENT
LOW TEMPERATURE
MECHANICAL PROPERTIES
MEDIUM TEMPERATURE
METALS
MICROSCOPY
MICROSTRUCTURE
MONOCRYSTALS
NIOBIUM
POLYCRYSTALS
QUANTITY RATIO
SCANNING ELECTRON MICROSCOPY
TEMPERATURE DEPENDENCE
TENSILE PROPERTIES
TRANSITION ELEMENTS
YIELD STRENGTH