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

The dual implantation of silicon and carbon ions into copper and iron was c arried out with an MeV ion accelerator. Analysis by transmission electron m icroscopy (TEM) revealed that the ion implanted layer of a Cu substrate is crystalline, while that of an Fe substrate is amorphous. The hardness was m easured as a function of the depth by a continuous stiffness measurement me thod with a nano indenter. Dual ion implantation was found to enhance the h ardness of a substrate, and the peak hardness occurred at a smaller depth t han the peak concentration of the implanted layer. Cross-sectional TEM imag es of ion implanted layers taken under the indentations with various depth showed that the indenter did not fracture the implanted layer, but rather d eformed it plastically. These data provide us with a qualitative understand ing of the hardening mechanism. (C) 2001 Elsevier Science B.V. All rights r eserved.