Synthesis, microstructural characterization and transport properties of a new (Ti2Nb)AlC2 ternary nanolaminate carbide solid solution.

A new (Ti 2 Nb)AlC 2 MAX phase solid solution is synthesized by hot isostatic pressing a powder mixture of sub-stoichiometric titanium carbide, niobium and aluminum. It is demonstrated that the synthesis temperature and Al content are key parameters to obtain a large volume fraction of 312 MAX phase solid solution. Rietveld refinement allows determining the cell parameters which are shown to vary from one sample to another. Thus, (Ti 2 Nb)AlC 2 is not a line compound but a disordered solid solution. The 312 MAX phase solid solution formation mechanism is discussed considering intermediate phases observed by scanning electron microscopy and analysed using energy dispersive X-ray spectroscopy. Finally, transport properties are characterized. It is demonstrated that electron-phonon coupling is more efficient than in Ti 3 AlC 2 and Ti 3 SiC 2 . • Successful synthesis of the 312 MAX phase (Ti 2 Nb)AlC 2 via a one-step reactive Hot Isostatic Pressing (HIP) process. • Using a 10 at% excess of aluminum at 1580 °C allows optimizing the (Ti 2 Nb)AlC 2 content, reaching 97.6 wt.%. • The magnetoresistance (MR) is proportional to the square of the charge carrier mobility, as it follows Kohler’s rule.