Mechanical, wear and corrosion behavior of Ti–6Al–xNb (x = 3.5–21 wt%) alloys manufactured by powder metallurgy

Abstract

In this study, Ti–6Al–xNb alloys with different Nb percentages (x = 3.5–21 wt%) were produced by the conventional powder metallurgy technique. After mixing and pressing the alloy powders in appropriate proportions, the green samples were sintered in a tube furnace under a vacuum atmosphere at 1200 °C for 2 h. The X-ray diffraction analysis (XRD) showed that all the alloys consist of α–Ti, TiNb (β–Ti) and AlNb2 phases. The results showed that the Ti–6Al–14Nb alloy among all alloys has the best mechanical properties, and the microhardness, tensile and flexural strength are 276.4 Vickers hardness (Hv0.2), 453 MPa and 1682 MPa, respectively. Tribological tests were carried out in both dry and wet conditions with Hanks' Balanced Salt Solution. While generally, the specific wear rates of the samples increased with Nb content up to 17.5 wt% under dry conditions, on the other hand, they increased with increasing Nb content under wet conditions. On the other hand, the specific wear rate increased with increasing the sliding distance. The best corrosion resistance alloy among all the samples was Ti–6Al–7Nb with −0.0968 V corrosion potential (Ecorr), 0.015 μA/cm2 corrosion current density (Icorr) values.