The Formation of Metal Carbide Layers by Elevated-Temperature Ion Implantation of Fe-Based Alloys

An Fe-i % C alloy has been implanted at approximately 600 °C with V to a fluence of 5 × 1017 ions/cm2 and with Nb to a fluence of 3 × 1017 ions/cm2. For both implantations, Auger analysis showed that a nominally stoichiometric metal carbide layer formed beneath the surface. Below this layer, which was depleted of Fe, the metal carbide concentration decreased gradually, giving a continually graded interface with the bulk. TEM analysis showed a continuous layer of fine-grained VC or NbC, which displayed a preferred Baker-Nutting orientation relation with the underlying a-Fe matrix.