The Diffusion of Hydrogen Through Carbonyl Iron at Temperatures from 800° to 1100° Centigrade

Abstract

The diffusion of hydrogen through hydrogen‐purified carbonyl iron shows breaks in the log (rate) vs. 1/T curve at 834, 909 (body‐centered→face‐centered phase change), 945, 1009, 1056, 1082 and 1103 deg. centigrade. These are average values for three samples of ``Mehl'' iron. The log (rate) vs. 1/T curves at these temperatures are composed of arcs, the above points being ends of these arcs. These points fall on a line whose slope is 4085 deg. Kelvin. Thus b in the expression exp (—b/RT) is given as 18,680 cal./g atom for these points. The above temperatures belonging to the ends of the arcs can be fitted to a Balmer type formula, i.e., T (°K) = C(1/3²—1/n²), where n = 6, 7, 8, ..., and C = 13,430±30 for the breaks starting with n = 7, while C = 13,301 for the break with n = 6. This difference is presumably caused by the n = 6 break being in the body‐centered phase, while all breaks starting with n = 7 are in the face‐centered phase.