Diffusion of boron in an amorphous iron-boron alloy

Abstract

We prepared by a sputtering technique a thin-film diffusion couple composed of amorphous iron (Fe) - boron (B) alloys (a-FeB) containing 16.5 at. % B, but the different ratios of stable isotopes of B with mass number, 10 and 11, and then obtained the interdiffusion profiles by secondary-ion mass spectrometry to evaluate the diffusion coefficient of B in a-FeB at 533 K - 653 K. The activation energy and pre-exponential factor for diffusion were determined to be 1.51 eV and 3.0 × 10−8 m2 s−1, respectively. The comparison with the reported data has revealed that boron is the fastest diffusion element in a-FeB. It was found that the activation energy for diffusion of B by present work was close to that for the crystallization of a iron in α-FeB, reported previously, suggesting that the diffusion of B is a rate-determining process for it.