Si在纯Fe及低硅钢中扩散行为

Diffusion behavior of silicon in pure iron and low-silicon steel substrates

采用磁控溅射方法,分别在纯Fe以及低硅钢基片上沉积富Si膜,并对其进行真空扩散热处理.通过能谱分析及X射线衍射研究了Si在纯Fe与低硅钢基体中的扩散特征,运用DICTRA软件建立了扩散模型.研究发现Si在纯Fe基体中扩散时发生γ-Fe(Si)→α-Fe(Si)相转变,扩散速率受控于相界面的迁移.当沿截面Si含量梯度不足以驱动相界面正向迁移时,延长扩散时间会发生相界面回迁现象,最终趋于单一相内均匀化扩散过程.Si在低硅钢基体中的扩散符合Fick扩散第二定律.

Si-rich films were deposited on pure iron and low-Si steel substrates by direct current magnetron sputtering,and then were subjected to vacuum annealing.The distribution characteristics of Si across Fe and low-Si steel substrates were studied by energy spectrum analysis（EDS） and X-ray diffraction（XRD）.DICTRA software was used to simulate the diffusion models.It is found that the diffusion behavior of Si in the Fe substrate is from γ-Fe（Si） phase to α-Fe（Si） phase and the rate of diffusion is controlled by phase-boundary migration.When the content gradient of Si along the cross section is not sufficient to drive the phase interface to positively migrate,the phase interface moves back with the increase of diffusion time,and the diffusion process tends to be a uniform diffusion process with the time passing.But in the low-Si steel substrate,the diffusion behavior of Si accords with the Fick＇s second law of diffusion.