Magnetic aftereffect of interstitial oxygen in iron

Abstract

Dynamical magnetic aftereffect and disaccommodation measurements were carried out on oxygen-alloyed iron alloys to prove experimentally the interstitial behaviour of oxygen. The dynamical aftereffect was superposed on carbon relaxation. By an appropriate mathematical method the measured curve was separated into components relating carbon and oxygen relaxation; in this way for oxygen the following parameters were found: Q=21,8kcal/mole; <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\tau_{c} = =3,4.10^{-15}</tex> sec; T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</inf> /10Hz/=355°K,T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</inf> /1000Hz/ = =417°K, showing a good agreement with theoretically estimated values. By disaccommodation measurements two different processes were found, with Q=25,8 kcal/mole; <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\tau_{o} =4,3.10^{-18}</tex> sec; and Q=22,4 kcal/mole; <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\tau_{o}=6,4.10^{-14}</tex> sec. The first relaxation is connected with CO pairs, the other is due to interstitial oxygen, and its parameters agree well with theory and dynamical aftereffect measurements. All these processes disappeared in alloys containing 600 wtppm Ti. In all samples a new, not expected effect was found at higher temperatures than that of normal interstitial relaxation.