Influence of Nitrogen Plasma Immersion Ionic Implantation (N-PIII) in Properties of Ti-6Al-4V

Materials with appropriate behavior at high temperatures and severe environments have become a necessity scientific, technological and economically nowadays. Studies have been conducted, independent business objectives to the improvement in getting new alloys and primarily to the revaluation of existing commercial alloys by means of data acquisition in conditions of more severity. In this work, it studied the Ti-6Al-4V alloy in surface treatment by plasma immersion ion implantation (PIII) with different implantation times, to obtain improvements in the tribological properties and creep resistance of the material. The alloy was submitted to PIII treatment to the nitrogen ion implantation, aiming the formation of a surface layer of TiN. The samples were characterized by the Auger, Raman, wear, X-ray diffraction, scanning electron microscopy, roughness superficial (AFM) and nanoindentation techniques. The alloy also was subjected to the creep tests at temperatures of 500, 600 and 700^oC in constant load. The obtained results showed the nitrites superficial in the alloys. The roughness values and hardness superficial increased accordingly implantation time, because the TiN formation decreasing analogously the wear coefficient. The PIII 3h samples showed lower creep resistance than without treatment samples. This lower creep resistance was verified by higher stationary creep rate and the decreasing of fracture time, it can be related to TiN formation on surface of the material promoting a fragile behavior to the alloy, decreasing its creep resistance. In the samples of 2h implantation time, the thin layer of TiN formed didn’t change significantly the ductile behavior of the alloy, protecting to oxidation in high temperatures and in creep performance. The values correlation of stress exponent and activation energy to stationary stage indicated that the creep mechanism to this work is associated to dislocation.