Submicro gradient hard alloy with cubic phase removed on surface layer and preparation method

The invention discloses a submicro gradient hard alloy with a cubic phase removed from a surface layer and a preparation method, the submicro gradient hard alloy comprises Co powder, Ti (Cx, N1-x) powder, (Wy, Ti1-y) C powder, TaC powder, W powder and WC powder, and adsorption oxygen and chemical oxygen of submicro WC powder, cubic phase carbide and other ceramic raw material powder are reduced through atmosphere protection heat treatment; the oxygen content of the mixed raw material powder is reduced, so that the decarburization problem of the gradient hard alloy is remarkably reduced, meanwhile, the content ratio of cubic phase metal elements to N can be controlled, and the submicro gradient hard alloy is obtained through vacuum pre-sintering and pressure final sintering treatment. And the deoxidation effect is remarkable, the porosity in the gradient hard alloy is reduced, the strength and hardness of the gradient hard alloy are promoted, and the obtained submicro gradient hard alloy has excellent wear res