Effect of Carbon on the Electrical Resistivity of Ni–Al Intermetallic Alloy Synthesized by an Electrothermal Explosion under Pressure

Abstract

The effect of carbon (3 wt %) on the electrical resistivity of alloys based on aluminum nickelides Ni–Al and Ni–Al–C synthesized by electrothermal explosion in the temperature range of 300–1300 K in a vacuum of 2 × 10–3 Pa has been studied. At an electrothermal explosion in a powder reaction medium, a Ni–Al-based melt is formed in which carbon dissolves. It is shown that, during the crystallization of the final product, due to its low solubility in Ni–Al, carbon is located at the boundaries of intermetallic grains of Ni–Al in the form of multilayer graphite nanofilms 50–80 nm thick, filling the intergranular space. It is shown that the synthesized alloys have a metallic character of conductivity, and the electrical resistivity in the measured temperature range of 300–1300 K increases monotonically for Ni–Al from 16 to 40 μΩ cm and for the carbon-bearing alloy Ni–Al–C from 22 to 60 μΩ cm. In this case, an increase in the temperature coefficient of resistance (TCR) is also observed from 1.45 × 10–3 K–1 for Ni–Al to 1.77 × 10–3 K–1 for Ni–Al–C. The slope of the curves of the dependence of electrical resistance on temperature in the studied temperature range of 300–1300 K remains constant and is well described by a linear function.