Hydrogen fragileness

Steel phases have an influence on the rate of corrosion. Ferrite has a weak resistance to pitting. The presence of martensite can increase the hydrogen fragilization of steel. Intermetallic phases as Fe2Mo in high Ni content alloys can influence the corrosion resistance. The precipitate CuA12 in aluminum alloys the series 2000 is more noble than the matrix, with corrosion around the precipitate. The majority of case histories reported in the literature have involved austenitic stainless steels, aluminum alloys, and to a lesser degree, some ferritic stainless steels and nickel-based alloys.31... 

Although argon is considered chemically inert, at low temperatures it is possible to combine argon with other atoms to form very fragile compounds, which exist only at those very low temperatures. For instance, it can combine with fluorine and hydrogen to form argon fluorohydride (HArF). It is only slightly soluble in water. 

As mentioned, it has recently been discovered that argon can only form fragile compounds with a few other elements at extremely low temperatures. For example, under extreme cold, argon can combine with fluorine and hydrogen to form the fragile molecule HArE... 

Protected and unprotected indole derivatives dissolved in hydrogen fluoride are also fluorinated by 18F-F. The relatively stable melatonin (10), a neurohormone responsible for the biological clock and other brain functions, gave only the 6-[l8F]fluoro derivative 11, but even the more fragile 5-hydroxytryptophan (12) could be fluorinated under these conditions resulting in a mixture of 4- and 6-[l8F]fluorohydroxytryptophan 13.54... 

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