Lattice Expansion as a Measure of Surface Segregation and Solubility of Hydrogen in α-FeTiH_X

Conference · Tue Jan 01 00:00:00 EST 1980 · Journal of the Less Common Metals

DOI:https://doi.org/10.1016/0022-5088(80)90358-6· OSTI ID:5429025

Reilly, J. J.; Johnson, J. R.; Reidinger, F.; Lynch, J. F.; Tanaka, J.; Wiswall, R. H.

The lattice expansion of α-FeTiH_X was found to be anomalously small as a function of hydrogen content. The apparent partial molar volume of hydrogen, anti V_H, was 0.1 ± 0.1 cc/g atom (FeTiH_<0.03), a value much lower than the accepted range of 2.2 to 1.4 cc/g atom previously reported for hydrogen-metal solutions. The behavior is attributed to preferential occupation by hydrogen of Ti rich sites produced by surface segregation effects which are known to occur in activated FeTi. The α/α+Β phase boundary is estimated to occur at an overall composition equivalent to FeTi_{≈ 0.04}. At this composition ≈ 85% of the total hydrogen content is estimated to be associated with surface layers ≈ 100 Å in depth. Unactivated FeTi (low surface area) behaved quite differently and it is clear that in the low dilution region surface segregation effects play a dominant role with respect to system behavior. Evidence is also presented that strain and dislocations produced by a hydriding-dehydriding cycle increase hydrogen solubility and shift the phase boundary towards higher hydrogen contents.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: EY-76-C-02-0016
• OSTI ID: 5429025
• Report Number(s): BNL-27523; CONF-800402-12; JCOMAH; TRN: 80-010588
• Journal Information: Journal of the Less Common Metals, Vol. 73, Issue 1; Conference: International Symposium on the Properties and Applications of Metal Hydrides, Colorado Springs, CO, USA, 7 Apr 1980
• Publisher: Copyright © 1980 Published by Elsevier B.V.
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
IRON HYDRIDES
VOLUME
TITANIUM HYDRIDES
CRYSTAL LATTICES
EXPANSION
PHASE STUDIES
SEGREGATION
CRYSTAL STRUCTURE
HYDRIDES
HYDROGEN COMPOUNDS
IRON COMPOUNDS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical &amp; Physicochemical Properties