Carbide and nitride/carbide layers in iron synthesized by ion implantation

Abstract

Stoichiometric iron carbide layers have been fabricated using a two-step implantation process. First, carbon pre-implantation at 400 keV is performed at low substrate temperature ( ∼50 ° C ) to form a region with high carbon concentration. For a pre-implantation dose of 7.5 × 10 17 cm −2 , annealing at 300 °C results in formation of stoichiometric Fe 3C (cementite) at the position of the pre-implanted atoms. When the pre-implanted specimen is implanted with 850 keV C + at 300 °C the Fe 3C layer grows by diffusion of implanted atoms through the iron substrate to the cementite layer. When a 400 keV carbon pre-implant is followed by implantation of 1 MeV nitrogen at 300 °C, γ′- Fe 4 N nucleates and grows on the carbide layer.