Effect of vanadium content on microstructure, mechanical properties, and oxidation behavior of novel high temperature complex alloy

Abstract

Introducing vanadium (V) in high temperature alloys reduces density and increases its high temperature strength. However, the effect of V on the high temperature oxidation behavior is debatable and hence unclear. In line with that, here we developed Co₃₀Ni_45-xV_xCr₁₅Fe₅Si₅ (at. %) (x = 5, 10, 15, 20, 25, 30) high temperature complex alloys (HT-CAs) (all elements in at. %.) with varying V content and studied its effect on microstructure, mechanical properties and high temperature oxidation behavior (for prolonged exposure of 96 h at 1050 °C) systematically. Microstructural evolution as a function of V content shows a steady transition from single phase f.c.c. structure to multi-phase structure beyond 15 at. % with good compressive formability (ε > 50 %) whereas oxide layer thickness displayed an exponential rise beyond 10 at. % of V with a gradual increase in weight gain upon oxidation. The increased layer thickness (>350 μm) and weight gain (>45 mg/cm²) after oxidation beyond 10 at. % V in these alloys is attributed to the increased V content in the oxide layer suggesting its higher reactivity with oxygen during high temperature exposure. Thus, higher V in the HT-CAs could be detrimental from mechanical properties and oxidation resistance perspectives, hence its content needs to be tailored to minimize the oxidation losses and maximize the component life during service.