Microstructure and thermal conductivity of RuAl2 prepared by a single-roll melt-spinning method

Abstract

The performance of thermoelectric (TE) materials is characterized by a dimensionless figure of merit (ZT). To achieve high ZT, it is important to reduce the thermal conductivity (κ). One known method for reducing the κ value of bulk materials is by controlling the microstructure. RuAl2 is known as a good TE material, although it has a relatively high κ value. In the present study, microstructurally controlled RuAl2 was prepared by a single-roll melt-spinning (MS) method. The obtained ribbons were crushed into powders and subjected to spark plasma sintering (SPS) to obtain high-density bulk samples. We measured the κ value of the obtained bulk samples and compared the data with that of a sample prepared by a traditional arc-melting method. The κ value of the MS-SPS sample was 13.5 W m-1 K-1 at room temperature, which was approximately 25% lower than that of the arc-melted sample. It can be concluded that the MS-SPS method is effective for making a RuAl2 bulk sample with moderately reduced κ value.