Ionhyphen;beam investigation of Sb diffusion and solubility in Fe

摘要

The diffusion coefficient and solid solubility of Sb in Fe have been measured over the temperature range 773les;Tles;873 K by ionhyphen;beam methods. This has extended previous diffusionhyphen;rate data downward by five orders of magnitude. Diffusion couples formed by ion implanting Sb into Fe were vacuum annealed, with composition versus depth being determined by ion backscattering analysis. Precipitation within the implanted region was characterized by transmission electron microscopy. Theoretical analysis of the data is based on coupled differential equations for the concentration profile and the precipitate radii. The resulting solid solubility of Sb in Fe is given byC0= (22.7 at.percent;) thinsp;exp(minus;1905K/T) for 773les;Tles;1273 K, where other data from higher temperatures have been included. The diffusion measurements may be described byD= (80 cm2/s) thinsp;exp(minus;32thinsp;460K/T) for 773les;Tles;873 K. Implications of these results for intergranular embrittlement by grainhyphen;boundary segregation of Sb are discussed.