Refractory metals mechanical alloying

As part of the early work to find alloys ofplatinum with higher reactivity for oxygen reduction than platinum alone, International Fuel Cells (now UTC Fuel Cells, LLC.) developed some platinum-refractory-metal binary-alloy electrocatalysts. The preferred alloy was a platinum-vanadium combination that had higher specific activity than platinum alone.25 The mechanism for this catalytic enhancement was not understood, and posttest analyses26 at Los Alamos National Laboratory showed that for this binary-alloy, the vanadium component was rapidly leached out, leaving behind only the platinum. The fuel- cell also manifested this catalyst degradation as a loss of performance with time. In this instance, as the vanadium was lost from the alloy, so the performance of the catalyst reverted to that of the platinum catalyst in the absence of vanadium. This process occurs fairly rapidly in terms of the fuel-cell lifetime, i.e., within 1-2000 hours. Such a performance loss means that this Pt-V alloy combination may not be important commercially but it does pose the question, why does the electrocatalytic enhancement for oxygen reduction occur ... 

It should be noted first that the mechanical properties of refractory metals and alloys are sensitive to minor impurities, such as O, C, and N levels, grain size and orientation, precipitates, dislocations, and other microstructural parameters. Moreover, impurity levels and microstractural states may change during high-temperature testing, which also influence the properties. Comparison of the mechanical properties is made in this section based on literature data, in which, however, details of the materials and testing information are unavailable in most cases. 

More than half of the elements in the Periodic Table react with silicon to form one or more silicides. The refractory metal and noble metal silicides ate used in the electronics industry. Silicon and ferrosilicon alloys have a wide range of applications in the iron and steel industries where they are used as inoculants to give significantly improved mechanical properties. Ferrosilicon alloys are also used as deoxidizers and as an economical source of silicon for steel and iron. 

The effect of rhenium on the properties of refractory metals has been a research topic of discontinuous relevance since its discovery in the 1950 s [1, 2], Several works have been devoted to the mechanical property enhancement seen in VIb group transition metals when solid solution alloyed with rhenium [3-12], In the 1970 s the works of... 

The main research interests of Vas ko were related to the electrochemistry of refractory metals where he was a well-known expert. He developed the process of galvanic coating of W-Ni and Mo-Ni alloys from aqueous electrolytes. Trying to explain the mechanism of this process, he assumed two stages of the formation of such alloys first, the deposition of solid film consisting of low-valency compounds and, second, electrochemical reduction of the film at the inner surface by solid mechanism. Thus, the solid non-metal film on the electrode surface for the first time became an active participant of the electrochemical process rather than simple passivative layer. This was a breakthrough. Further on, this electrochemical film system (EFS) concept was usefully applied not only in the aqueous electrochemistry but in the electrochemistry of molten salts and ionic liquids as well (see [7] for more details). 

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