Microstructural investigations of iron implanted with nitrogen ions at the temperature of liquid nitrogen: Part II: Implantation in the dose range 1×1017 to 1×1018 N+-ions/cm2

Abstract

Surface compositions and microstructures of iron implanted with nitrogen ions to high fluences between 1×10 17 and 1×10 18 N + -ions/cm 2 at the temperature of liquid nitrogen have been examined by Auger electron spectroscopy, high-voltage electron microscopy and transmission high-energy electron diffraction. In part I of this paper [1], we have reported on the microstructure of nitrogen-implanted iron up to a dose of 1×10 17 N + -ions/cm 2 . The nitrogen distribution profiles are very different from the distribution predicted by the LSS-theory and from the profiles after implantation at room temperature. The nitrogen ion implantation at the temperature of liquid nitrogen leads to α′-iron nitrogen martensite, α″-Fe 16 N 2 and ∈-Fe 2 (C, N) 1− x . The structure and the habit of these phases and solid solutions are discussed as function of the implantation dose. The implantation-induced microstructure after implantation at the temperature of liquid nitrogen differs from that of implantation at room temperature. The phase formation is described by a model of implatation-induced transformation.