TEM study of hydrogen-containing precipitates in Al-containing ODS steel

The production process of ODS steels for application in fusion technology includes mechanical alloying as a preparation step where hydrogen is used as a protection gas. The hydrogen incorporated in the steel powder during this procedure forms the Al(OH)x phase inside the Al2O3 precipitates. The hydroxide phase can be detected by electron energy loss spectroscopy. During the work reported here, it was found that the hydrogen inside ODS steel forms complex Al2O3/Al(OH)x precipitates exhibiting different morphologies and spatial distributions of the Al(OH)x phase. Thermal stability of the Al(OH)x phase was studied by in situ TEM heating experiments.