Hydrogen mechanical alloying with

This could have far-reaching consequences, as mechanically induced disorder can be a factor in activation of well-ordered intermetallic compounds (alloys) for reversible reactions with molecular hydrogen. Figure 1.20b shows the PCT plots, which details hydrogen sorption properties for B2-type FeTi, an important hydrogen storage alloy with capability for reversible storage at room temperature applications. The plateau of equilibrium sorption is lowered in ball milled, disordered FeTi in comparison with the not-milled counterpart. Therefore, the alloy has been... 

As shown by the studies on rare-earth permanent magnets, the non-equilibrium structures developed by mechanical alloying, with or without subsequent heat treatment, exhibit unique properties. There is thus much potential for the development of new mechanically alloyed materials for applications such as catalysts, electrodes, hydrogen-storage containers and other applications, where property improvements are associated with the amorphous and nanocrystalline structures developed by mechanical alloying. 

Hydrogen effect on the mechanical properties discussed below was studied on several a and a+fi alloys with the following nominal composition of metallic components (Russian trade marks given in parentheses) commercial titanium of nominal purity 99.3% (VTl-0), Ti-6Al-2Zr-1.5V-lMo (VT20), Ti-6A1-4.5V (VT6), Ti-6Al-2.5Mo-2Cr (VT3-1), Ti-4Al-1.5Mn (OT4), Ti-6.5Al-4Mo-2Sn-0.6W-0.2Si (VT25u) and others. The main features of their stress-strain behavior due to hydrogenation were much similar, but some individuality was characteristic of each alloy. 

In the previous Sections, bulk specimens were alloyed with hydrogen from the gas phase. It was interesting to see whether hydrogen affects the mechanical properties of titanium in a similar way if metal is in a powder state and hydrogen is introduced by mechanical mixing of the metal powder with titanium dihydride, or the interparticle boundaries axe an insurmountable obstacle for hydrogen an eliminate the effects observed in bulk specimens. 

H. Imamura, Y. Takesue, T. Akimoto, S. Tabata, Hydrogen-absorbing magnesium composites prepared by mechanical grinding with graphite effects of additives on composite structures and hydiiding properties, J. Alloys Compd. 293-295 (1999) 564-568. 

A purely bifunctional mechanism was assumed to be operative in the CO oxidation on Pt3Sn surfaces as well as on other Pt alloys with oxophilic transition metals [157-159]. Here, the oxophilic Sn surface atoms are believed to provide nucleation sites for water and, following stepwise hydrogen abstraction, for its subsequent oxygenated surface products OH and O. CO oxidation on Sn atoms is unlikely [131,160] such that no competition for Sn sites occurs between water and CO molecules. All Pt atoms are covered with CO. 

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