An investigation of the effect of surface impurities on the adsorption kinetics of hydrogen chemisorbed onto iron. Annual status report, 1 January-31 December 1994
The goal of this program has been to develop an understanding of heterogeneous kinetic processes for those molecular species which produce gaseous hydrogen degradation of the mechanical properties of metallic structural materials. During the present program, the interaction of hydrogen with the surfaces of alpha-2 (Ti3Al) titanium aluminide, gamma (TiAl) titanium aluminide, and beryllium were studied. The interaction of low pressure hydrogen with gamma titanium aluminide and beryllium was found to be relatively weak. Weak in the sense that adsorption leads to a low surface concentration of dissociated hydrogen, i.e., the chemisorption process is reversible at room temperature (300 K) for gamma titanium aluminide and the sticking coefficient for chemisorption is extremely small for beryllium. Hydrogen was found to interact readily with alpha-2 titanium aluminide to form a stable surface hydride at 300 K. These results correlate well with other recent studies which show that the mechanical properties for alpha-2 titanium aluminide are readily degraded in hydrogen while gamma titanium aluminide exhibits less degradation and beryllium essentially no degradation. The interaction of oxygen with the surface of several of these materials was studied. More recently, preliminary hydrogen permeation studies were completed for three high temperature alloys, Incoloy 909, Mo-47.5Re (wt. %), and this past year, Haynes 188.
- Research Organization:
- California Univ., Santa Barbara, CA (United States)
- OSTI ID:
- 63495
- Report Number(s):
- N-95-24400; NASA-CR-197967; NAS-1.26:197967; CNN: NCC2-63; TRN: 9524400
- Resource Relation:
- Other Information: PBD: Dec 1994
- Country of Publication:
- United States
- Language:
- English
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