Estudo da nitretação por plasma na fluência da liga TI-6Al-4V

Abstract

The aim of this work is to try to improve the creep resistance of Ti-6Al-4V alloy using a surface treatment by plasma nitriding. The nitriding was performed by varying parameters such as time, temperature and the nitrogen content in the gas atmosphere. A nitrogen-argon mixture, with a small part of hydrogen, was used in order to determine the best conditions for the formation of the nitride layer. The phases of all the nitrided samples detected by XRD were the ε-Ti2N phase and δ-TiN, in addition to the α-Ti and β-Ti matrix phases. In the case of the treated sample with 50% nitrogen in the gas atmosphere was chosen as the best condition. The increase of the relative intensities of the peaks assigned to ε-Ti2N and δ-TiN phases and the decrease of those assigned to the α-phase indicates a larger thickness. The layer thickness of this sample was about 12 μm. Subsequently, creep tests were performed on the material in the best condition. The creep resistance resulting from the nitrided material shows a decrease in the secondary creep rate and an increase in the final creep time when compared to the material without treatment.