as mechsm is unkely to be the predormnant mechsm
m an oxldtzmg atmosphere (au or oxygen) The vahdIty of a
smgle stage equahon (1) over the entue range IS quefionable
even m an mtert atmosphere (argon or mtrogen) In th~s paper,
we have restncted our analysis to the commonly used models
and methodology, so as to enable a comparahve evaluahon
The hmtahon of these models and altemhve approaches are
bemg emed and reported separately
The rate of disappearance of A may be represented by the
followmg relahon