Observation and characterisation by transmission electron microscopy of helical dislocation in Cr ₂ AlC MAX phase

The monocrystalline Cr2AlC MAX phase has been studied and characterised by Transmission Electron Microscopy (TEM) after spherical nanoindentation tests. Observations have shown, for the first time, the existence of a helical dislocation in these materials. The characteristics and parameters of the cited dislocation have been deduced via the extinction criteria, and the formation mechanism has been discussed in relation to the literature. These findings suggest that the formation of such a defect is related to the synthesis method (high-temperature solution growth) rather than the mechanical test.