Abstract
Alloys containing up to four multi-principal elements in equiatomic ratios are referred
to as medium entropy alloys (MEA). These alloys have attracted the interest of many researchers
due to the superior mechanical properties it offers over the traditional alloys. The design
approach of MEA often results to simple solid solution with either body centered cubic; face
centered cubic structures or both. As the consideration for introducing the alloys into several
engineering application increases, there have been efforts to study the corrosion behaviour of
these alloys. Previous reports have shown that some of these alloys are more susceptible to
corrosion when compared with traditional alloys due to lack of protective passive film. In this
research, we have developed AlFeTiV medium entropy alloys containing two elements (Ti and
Al) that readily passivate when exposed to corrosive solutions. The alloys were produced in
vacuum arc furnace purged with high purity argon. Open circuit potential and potentiodynamic
polarisation tests were used to evaluate the corrosion behaviour of the as-cast AlFeTiV alloy in
3.5 wt% NaCl and 1 M H2SO4. The corrosion performance of the alloy was compared with Ti-
6Al-4V alloy tested under similar conditions. The results show that unlike in Ti-6Al-4V alloy,
the open circuit potential of the AlFeTiV alloy move towards the negative values in both 3.5
wt% NaCl and 1 M H2SO4 solutions indicating that self-activation occurred rapidly on
immersion. Anodic polarisation of the alloys showed that AlFeTiV alloy exhibited a narrow
range of passivity in both solutions. In addition, the alloys exhibited lower Ecorr and higher
Icorr when compared with traditional Ti-6Al-4V alloy. The traditional Ti-6Al-4V alloy showed
superior corrosion resistant to the AlFeTiV alloy in both 3.5 wt.% NaCl and 1 M H2SO4
solutions.