Effects of helium implantation on hardness of pure iron and a reduced activation ferritic-martensitic steel

Helium was implanted into high purity Fe and F82H at room temperature up to 2000 appm to investigate helium effects on hardening. Ultra micro-indentat ion tests were performed on the specimens before and after helium implantat ion with loads that penetrate in 300 nm depth. After the indentation tests, the specimens were prepared with a focused ion beam (FIB) processing syste m for transmission electron microscopy (TEM) of the deformed regions. Resul ts of the indentation tests indicated clearly that helium implantation caus ed hardening for both pure Fe and F82H. For pure Fe, it was also observed b y TEM that the propagation of the plastic deformation zone formed during th e indentation was limited to the helium-implanted layer, ranging from 600 t o 800 nm from the incident surface. (C) 2000 Elsevier Science B.V. All righ ts reserved.