Kinetics of zirconium saturation with nitrogen during high-temperature nitridation

Zirconium samples in the form of ribbons 60 mm in length and 3.0 x 0.5 mm in cross section were heated in a nitrogen atmosphere at temperatures of 1500, 1800, 1965, and 2400A degrees C. The nitridation time at each temperature was 4, 6, 11, 21, 30, 40, 50, and 60 min. It has been shown that, under the thermal conditions studied, the process of saturation with nitrogen involves two stages: the first stage (in which the metallic phase disappears) can be represented by an exponential rate law, and the second (corresponding to an increase in nitrogen content up to the stoichiometric composition of ZrN) has a linear rate law.