Effect of carbon on the electrical resistivity of Ni – Al intermetallic alloy synthesized by an electrothermal explosion under pressure

In this paper, we studied the effect of carbon (3 wt. %) on the electrical resistivity of materials based on Ni − Al and Ni – Al − C synthesized by the electrothermal explosion in the temperature range 300 – 1300 K in a vacuum of 2·10–3 Pa. During an electrothermal explosion, a Ni – Al-based melt is formed in a powder reactive medium, in which carbon is dissolved. It is shown that during the crystallization of the final product, due to its low solubility in NiAl, carbon is located on the surface of intermetallic NiAl grains in the form of multilayer graphite nanofilms 50 – 80 nm thick, filling the intergranular space. It is shown that the synthesized materials have a metallic conductivity, and the electrical resistivity in the measured temperature range of 300 – 1300 K increases monotonically for the Ni – Al-based alloy from 16 to 40 mW·cm and for the carbon-containing Ni – Al – C material from 22 to 60 mW·cm. The temperature coefficient of resistance (TCS) also increases from 1.45·10–3 K–1 for NiAl to 1.77·10–3 K–1 for NiAl/C. The slope of the resistivity curves in the studied temperature range of 300 – 1300 K remains constant and is well described by a linear function.