55Fe diffusion in magnetite crystals at 500° C and its relevance to oxidation of iron
55Fe diffusion in magnetite crystals at 500° C and its relevance to oxidation of iron
复制标题
DOI：
10.1007/bf00541841
复制
发表时间：
1983-08
影响因子：
4.5
通讯作者：
A. Atkinson;M. O'dwyer;R. I. Taylor
中科院分区：
文献类型：
--
作者：
A. Atkinson;M. O'dwyer;R. I. Taylor
本文介绍了一种计算机控制的自扩散切片装置，它特别适用于低温（D在10 - 12 ~ 10 - 19厘米2秒-1范围内）下的自扩散研究。该技术已用于测量500° C下55 Fe在磁铁矿晶格中的扩散系数与氧活度的关系。结果与预先存在的高温扩散数据（T>900°C）的外推大致一致。低温数据已被用于估计在500° C下在CO2+ 1体积% CO中在铁上形成磁铁矿的速率常数，并且发现这比实验测量值小250倍。这种分歧可能是由于扩散沿着氧化物晶界在氧化过程中。还根据扩散数据计算了铁在氧气中氧化过程中形成磁铁矿的速率常数，并将其与325 ° C至1100°C温度下测得的速率常数进行了比较。
A computer controlled sputter-sectioning apparatus is described which is particularly useful for self diffusion studies at “low” temperatures (Din the range 10−12to 10−19cm2sec−1). The technique has been applied to measure the diffusion coefficient of55Fe in the magnetite lattice as a function of oxygen activity at 500° C. The results are in broad agreement with an extrapolation of pre-existing high temperature diffusion data (T>900°C). The low temperature data have been used to estimate the rate constant for magnetite formation on iron in CO2+ 1 vol% CO at 500° C and this is found to be 250 times smaller than the experimentally measured value. This disagreement is probably attributable to diffusion along oxide grain boundaries during oxidation. The rate constant for the formation of magnetite during the oxidation of iron in oxygen has also been calculated from the diffusion data and is compared with the measured rate constant for temperatures between 325 and 1100°C.