Permeation, Diffusion, and Solution of Nitrogen in Tungsten and Molybdenum

摘要

Using ultrahighhyphen;vacuum and masshyphen;spectroscopic techniques, permeation, diffusion, and solution of nitrogen in W and Mo have been measured for pressures between 5thinsp;times;thinsp;10minus;5and 500 torr and for temperatures between 1100deg; and 2500deg;K. The following values for the permeation constants,P(torrmiddot;liter/cmmiddot;secmiddot;torr1/2), diffusion constants,D(cm2/sec), and solubility constants,S(torrmiddot;liter/cm3middot;torr1/2), are obtained:Plpar;Wrpar;thinsp;equals;thinsp;1.6thinsp;times;thinsp;10minus;4explpar;minus;thinsp;52 000thinsp;sol;thinsp;RTrpar;;Plpar;Morpar;thinsp;equals;thinsp;6.1thinsp;times;thinsp;10minus;3explpar;minus;thinsp;47 500thinsp;sol;thinsp;RTrpar;;Dlpar;Wrpar;thinsp;equals;thinsp;5.4explpar;minus;thinsp;62 000thinsp;sol;thinsp;RTrpar;;Dlpar;Morpar;thinsp;equals;thinsp;2.3thinsp;times;thinsp;10minus;2explpar;minus;thinsp;33 000thinsp;sol;thinsp;RTrpar;;Slpar;Wrpar;thinsp;equals;thinsp;3.0thinsp;times;thinsp;10minus;5explpar;plus;thinsp;10 000thinsp;sol;thinsp;RTrpar;;Slpar;Morpar;thinsp;equals;thinsp;2.6thinsp;times;thinsp;10minus;1explpar;minus;thinsp;14 500sol;RTrpar;. For nitrogen in Mo, the diffusion constant is in agreement with Zener's theory of interstitial atomic diffusion. For nitrogen in W, the frequency factor of the diffusion constant and the diffusion activation energy are abnormally high and not in agreement with Zener's theory.