Surface gas nitriding of Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo-0.08Si alloys

Abstract The paper presents results from thermochemical surface gas nitriding of Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo-0.08Si alloys using differential scanning calorimetry equipment. The experiments were carried out in nitrogen atmosphere at temperatures of 950 and 1050°C for 1, 3 and 5 h. Results for the surface hardness, the microhardness profiles and the thickness of the nitrided layers were obtained. Microstructure analyses were made by optical microscopy. X-ray diffraction analyses indicated new phases formed (TiN, TiN0.3, Ti2N and TiO2), depending on the time and the temperature of nitriding. The obtained thickness of the nitrided layers was in the range 60–320 μm depending on the process parameters. The Vickers microhardness along the cross-section depth varied between 610 and 1700.