In this work, manganese-doped (Cr1-xMnx)2AlC phases were synthesized by self-propagating high-temperature synthesis. The synthesis was carried out in a 3 L reactor under an initial argon pressure P0 = 5 MPa with the calculated x values of 0.05, 0.15, and 0.30. The diffraction peaks of the MAX phase in the manganese-containing samples were found to be shifted relative to the positions of the Cr2AlC peaks, indicating the substitution of a part of chromium atoms by manganese atoms. The manganese content in the MAX phase was estimated by energy-dispersive X-ray spectroscopy (EDS) after purifying the phase in hydrochloric acid. The measured manganese concentration corresponded to x = 0.015, 0.035, and 0.15. The synthesized (Cr1-xMnx)2AlC phases were compacted to a residual porosity of 20% and then infiltrated with copper melt. The infiltration was performed by depositing a melt droplet onto the sample surface and holding it at 1150°C in a vacuum of 10-3 Pa. The examination of the infiltrated phase structure revealed complete or partial decomposition of the MAX phases and the fusion of individual grains, resulting in a mechanically robust sample. The resulting submicron structure consists of a nanoscale chromium carbide skeleton infiltrated with Cu(Al, Cr, Mn) bronze. The mechanical properties were evaluated by measuring the microhardness both inside and outside the infiltrated region. It was shown that manganese reduces the hardness of the composite structure and, at high content, suppresses the formation of chromium carbide. The resulting composite structures with low or no manganese content show high potential for applications as wear- and corrosion-resistant conductive materials.
Gorshkov et al. (Sun,) studied this question.