B2相FeAl合金的电化学氢扩散行为

以铁粉和铝粉为原料,应用粉末冶金方法制备了B2相FeAl合金,采用电化学方法研究了B2相FeAl合金的电化学氢扩散行为。结果表明:制备所得B2相FeAl合金中的孔洞少而小,组织中出现类似于珠光体的黑白相间条状亚结构的偏析区域,且偏析区域的铝含量高于未偏析区域的;不同阴极充氢电流密度下的稳态氢扩散电流密度均略小于极限氢扩散电流密度;在B2相FeAl合金中氢的扩散通量、有效扩散系数、溶解度均随着阴极充氢电流密度的增加而增大;在阴极充氢电流的作用下,充氢端一侧合金表面的氢脱附反应速率常数远大于吸附反应速率常数,只有极少数的氢能够吸附到合金表面并渗入到合金中,说明在室温水汽环境下B2相FeAl合金氢脆的发生较为缓慢。

Electrochemical Hydrogen Diffusion Behavior of B2 Phase FeAl Alloy

The B2 phase FeAl alloy was prepared by powder metallurgy method with iron powder and aluminum powder as raw materials.The electrochemical hydrogen diffusion behavior of B2 phase FeAl alloy was studied by electrochemical method.The results show that the pores in the prepared B2 phase FeAl alloy were few and small,and the segregation region with black and white stripe-like substructure similar to pearlite appeared in the microstructure.The aluminum content in the segregation region was higher than that in the unsegregated region.The stabilized hydrogen diffusion current density was slightly smaller than the limited hydrogen diffusion current density at different hydrogen current densities.The diffusion flux,effective diffusion coefficient and solubility of hydrogen in B2 phase FeAl alloy increased with the increase of cathode hydrogen charging current density.Under the action of cathode hydrogen charging current,the hydrogen desorption rate constant of alloy surface on the hydrogen charging end side was much larger than the adsorption reaction rate constant.Only a very small amount of hydrogen could be adsorbed to the surface and penetrated into the alloy,indicating that the occurrence of hydrogen embrittlement in the B2 phase FeAl alloy was relatively slow in the water vapor environment at room temperature.