Shear and delamination behaviour of basal planes in Zr3AlC2 MAX phase studied by micromechanical testing

TL;DR

This study investigates the micromechanical behavior of Zr3AlC2 MAX phase, revealing its strength and brittleness differences compared to Ti3SiC2, through in situ electron microscopy testing methods.

Contribution

It provides new insights into how chemical composition influences the micromechanical properties of MAX phases, using advanced testing techniques.

Findings

Zr3AlC2 is stronger but more brittle than Ti3SiC2 at the microscale.

Distinct differences in basal slip strength and fracture energy were observed.

Results inform material selection and design for engineering applications.

Abstract

The mechanical properties of layered, hexagonal-structured MAX phases often show the combined merits of metals and ceramics, making them promising material candidates for safety critical applications. While their unique mechanical performance largely arises from the crystal structure, the effect of chemistry on the properties of these materials remains unclear. To study this, here we employed two in situ electron microscope small scale testing approaches to examine the micromechanical properties of Zr3AlC2, and compared the results with the properties of Ti3SiC2: we used micropillar compression tests to measure basal slip strength, and double cantilever beam splitting tests to evaluate fracture energy for basal plane delamination. We observed distinct and systematic differences in these measured properties between Zr3AlC2 and Ti3SiC2, where Zr3AlC2 appeared to be stronger but more brittle at the microscale, and discussed the implications of the results in the selection, design, and engineering of MAX phases for targeted engineering applications.