# Bonding and oxidation protection of Ti${_2}$AlC and Cr${_2}$AlC for a Ni-based Superalloy

## TL;DR

This study investigates the bonding behavior and oxidation resistance of Ti2AlC and Cr2AlC MAX phases with a Ni-based superalloy, demonstrating Cr2AlC's potential as an oxidation barrier at high temperatures.

## Contribution

It provides new insights into the bonding conditions and oxidation protection capabilities of Ti2AlC and Cr2AlC MAX phases with Ni-based superalloys.

## Key findings

- Cr2AlC forms a good diffusion bond with Ni-based superalloy at 1000°C and 2 MPa.
- Ti2AlC requires higher temperature and pressure for bonding and is a poor oxidation barrier.
- Cr2AlC effectively prevents oxidation of Inconel-718 after thermal cycling.

## Abstract

Alumina forming, oxidation and thermal shock resistant MAX phases are of a high interest for high temperature applications. Herein we report, on bonding and resulting interactions between a Ni-based superalloy, NSA, and two alumina forming MAX phases. The diffusion couples Cr${_2}$AlC/Inconel-718/Ti${_2}$AlC were assembled and heated to 1000 or 1100{\deg}C in a vacuum hot press under loads corresponding to stresses of either 2 MPa or 20 MPa. The resulting interfaces were examined using X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Good bonding between Cr${_2}$AlC and NSA was achieved after hot pressing at 1000{\deg}C and a contact pressure of only 2 MPa; in the case of Ti${_2}$AlC a higher temperature (1100{\deg}C) and pressure (20 MPa) were needed. In both cases, a diffusion bond was realized with no evidence of interfacial damage or cracking after cooling to room temperature. Twenty thermal cycles from room temperature to 1000{\deg}C showed that Ti${_2}$AlC is a poor oxidation barrier for Inconel-718. However, in the case of Cr${_2}$AlC no cracks, delamination nor surface degradation were observed, suggesting that this material could be used to protect Inconel-718 from oxidation.

---
Source: https://tomesphere.com/paper/1902.10001