You have to be more clear in what you want. Generally speaking, there are only some alloys that can offer better properties in carbon diffuses in the superficial layer (i.e. low carbon steels and some others special cases). And for that, active carbon atoms must have intimate contact with their surfaces.
The aim is to fabricate nanocomposite in molten salt. Carbonaceous materials are synthesized in molten salt and by adding a metal to the molten salt, carbon diffuse to metal, but I don't know can I control the diffusion rate?
Dear Mehdi , It is always depends on the how much %C present in the alloy and process parameters such as carbon potential ,pressure , total soaking time and temperature, By adjusting these parameters you can change the carbon diffusion rate but it needs some experiments.