A method of material treatment in which the surface of a metal substrate is converted to a composite structure of the metal and its nitride or carbide utilizing a high temperature chemically active thermal plasma stream, and the product obtained from that method. The complex thermal plasma contains controllable additions of active gas, liquid or solid substances. The surface layer obtained is functionally graded to the substrate resulting in an excellent bond that resists delamination and spalling, and provides a significant increase in hardness, wear and erosion resistance, and corrosion resistance, and a decrease in coefficient of friction.