The Electrical Resistivity of Multiphase Systems Based on the Ti3AlC2 Hexagonal Phase at Low Temperatures

Abstract

The electrical resistivity of three samples is measured in the range 4.2–295 K. One sample contains the pure Ti3AlC2 MAX‐phase, and the other two samples contain this phase together with inclusions of TiC, TiO, and Al2O3 phases. To estimate the value of the residual resistivity of the TiC phase, data of energy‐dispersive X‐ray spectroscopy concentration distributions of elements are used. Estimations show that the Ti3AlC2 phase has the smallest residual resistivity of all phases and can electrically shunt other phases. The approximation of temperature dependences of the resistivity reveals that the Bloch–Grüneisen term of scattering of electrons on phonons (i.e., the term proportional to T5) increases strongly with the increase of volume fractions of inclusions. According to the proposed explanation of this effect, interstitial impurities of the carbon in the Ti3AlC2 phase migrate to neighbor crystals of the titanium carbide during the formation of the MAX phase, so the purification of this phase from carbon appears. As all other phases are electrically shunted by the Ti3AlC2 phase, the Bloch–Grüneisen term of the resistivity of this purified Ti3AlC2 phase increases.