Fracture of niobium hydride

Journal Article · Mon Sep 01 00:00:00 EDT 1980 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(80)90075-9· OSTI ID:5105685

Gahr, S; Makenas, B J; Birnbaum, H K

Consideration is given to causes for the extreme brittleness observed for most hydrides. Surface energies for cleavage of the ..beta.. NbH/sub 0.82/ f.c. orthorhombic hydride along the (100)/sub c/ and (110)/sub c/ are obtained using fracture mechanics methods. The values are shown to be about equal to those of b.c.c. niobium. The relative surface energies of niobium and NbH are consistent with measurements of phonon frequencies and elastic constants. None of the data indicates any decrease of atomic bonding due to the incorporation of hydrogen in the metal lattice. Dislocation mobility is considered on the basis of T.E.M. observations and the crystal structure. It is shown that half of the (110)/sub c/<111>/sub c/ slip systems cause hydrogen disordering and therefore experience a high lattice frictional stress. Domain boundaries also are shown to be dislocation barriers. Hydride brittleness is considered to result from the decrease in dislocation mobility and in the slip systems available to cause plastic blunting at elastic discontinuities.

• Research Organization: Univ. of Illinois, Urbana-Champaign
• OSTI ID: 5105685
• Journal Information: Acta Metall.; (United States), Vol. 28:9
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
NIOBIUM
FRACTURE PROPERTIES
HYDROGEN EMBRITTLEMENT
NIOBIUM HYDRIDES
BRITTLENESS
CRYSTAL LATTICES
DISLOCATIONS
ENTHALPY
INTERNAL FRICTION
MOBILITY
SURFACE ENERGY
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
EMBRITTLEMENT
ENERGY
FREE ENERGY
FRICTION
HYDRIDES
HYDROGEN COMPOUNDS
LINE DEFECTS
MECHANICAL PROPERTIES
METALS
NIOBIUM COMPOUNDS
PHYSICAL PROPERTIES
REFRACTORY METALS
SURFACE PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
360103* - Metals &amp; Alloys- Mechanical Properties