What is a carbon free martensite?
Common martensite in iron based alloys, the essence of carbon and alloy elements (or) in alpha iron in the supersaturated solid solution. The iron carbon alloy is two yuan, carbon in alpha iron in the supersaturated solid solution.
The definition of martensite of Fe based alloy (solid steel and other iron-based alloy) and non ferrous metals and alloys, is guetche variant diffusion free phase transition product of martensitic transformation. It is a product of Fe based alloy, phase transformation of undercooled austenite occurs without diffusion were guetche formation of martensite variant body transformation.
Thus, I think the non carbon martensite should refer to the martensite formed by ferrous alloy (non carbon), but the carbon in the iron is difficult to be completely removed
