Origin of anomalous laminar cracking, volume expansion and weight increase of Ti2AlC MAX phase powders at 600 °C

Abstract

Planar cracks tend to form in Al-containing Mn+1AXn phase materials after oxidation at an intermediate temperature range between 550 and 650 °C, although they have outstanding oxidation resistance beyond 1200 °C. Herein, Ti2AlC Mn+1AXn phase powders are employed as a model example to investigate such laminar cracks formation at 600 °C, accompanying with continuous volume expansion and weight increment with oxidation duration. Coupled with the crystallinity structure development during oxidation, density function theory calculation has been performed to elucidate the origin of such anomalous behavior at 600 °C for Ti2AlC, which can be applicable to other Mn+1AXn phase materials.