Oxidation behavior of lightweight Al2NbTi3V2Zr high entropy alloy at 1000°C

Abstract

Lightweight high entropy alloy (LWHEA) has great potential in aeroengine hot component applications. Anticorrosion property of LWHEA at high temperatures is one of the key determining factors. In this study, an LWHEA containing Al, Nb, Ti, V, and Zr elements with a molar ratio of 2: 1: 3: 2: 1 was designed and prepared by low energy (LE) and high energy (HE) mechanical milling followed by vacuum hot pressing. The sintered LE alloy consisted of a simple cubic matrix and α intermetallic while the BCC matrix along with α and β intermetallic phases were observed in HE alloy. The oxidation of LE and HE at 1000°C for 48 h was mainly concentrated on α and β phases, and the resultant oxides were ZrO₂ and TiO₂. Weight gain curve of HE sample within oxidation time of 48 h followed the parabolic law while a two-stage parabola was found in LE bulk. The steady-state oxidation of α precipitate was dominant within 12 h and showed a preferential oxidation mode. High temperature induced simple cubic matrix to stable BCC phase transformation and thus LE alloy with longer oxidation time and HE exhibited a similar uniform oxidation. The oxidation rate of the alloy is related to the content of α and β phases.