Characterization of mechanical properties and microstructure of high-energy dual ion implanted metals

Abstract

The dual implantation of silicon and carbon ions into copper and iron was carried out with an MeV ion accelerator. Analysis by transmission electron microscopy (TEM) revealed that the ion implanted layer of a Cu substrate is crystalline, while that of an Fe substrate is amorphous. The hardness was measured as a function of the depth by a continuous stiffness measurement method with a nano indenter. Dual ion implantation was found to enhance the hardness of a substrate, and the peak hardness occurred at a smaller depth than the peak concentration of the implanted layer. Cross-sectional TEM images of ion implanted layers taken under the indentations with various depth showed that the indenter did not fracture the implanted layer, but rather deformed it plastically. These data provide us with a qualitative understanding of the hardening mechanism.