Surface mechanical effects of nitrogen ion implantation on vanadium alloys

Abstract This paper describes the modifications introduced by nitrogen implantation on V5 at.% Ti alloys at high energy. Two sets of samples were treated with three successive atomic and molecular nitrogen implantations, in order to obtain flat profiles of nitrogen concentration, namely 20 and 40%. On implanted samples microhardness tests with a final load of 2 mN showed a hardness increase by a factor of 2. Auger electron spectroscopy and X-ray photoelectron spectroscopy were used to identify the concentrations and chemical states of the elements present in the high dose implanted V5Ti surface. The obtained results indicate a correlation between the hardness increase and the nitrogen implantation. From the spectroscopic results we can distinguish three different regions: an amorphous carbon layer up to 10 nm from the surface, followed by an interface of mixed amorphous carbon and carbide (VC–TiC) of approximately 20 nm, in which nitrogen is in the form of nitride. The third region from 30 nm is characterized by a decrease in the oxygen concentration of 40%, together with slight nitrides increase and stable carbides.