The effectiveness of active screen method in ion nitriding grade 5 ELI titanium alloy

Abstract

A titanium alloy for biomedical applications, Grade 5 ELI, was studied, which was subjected to the ion nitriding process in the temperature range of 530 – 590 °C and during 5 – 17 h, using two variants of sample arrangement in the glow discharge chamber. The first variant – the samples intended for nitriding were placed on the cathode, the second variant – the samples placed on the cathode were shielded with an active screen. In order to assess the effectiveness of nitriding, studies were carried out on the depth of nitrogen diffusion into the substrate of the studied titanium alloy, surface hardness tests, as well as observation of the obtained microstructures and phase composition tests – in order to assess the structure of the surface layers. It was found that using active screens increases the rate of nitrogen diffusion deep into the nitrided Grade 5 ELI titanium alloy, and thus increases the thickness of the obtained nitrided layers.

Keywords

• titanium alloys
• biomedicine
• ion nitriding
• active screen method
• microhardnes
• microstructures