Microstructure manipulation by laser-surface remelting of a full-Heusler compound to enhance thermoelectric properties

TL;DR

This study demonstrates that laser surface remelting can effectively modify the microstructure of Fe2VAl Heusler compounds, reducing thermal conductivity and electrical resistivity, thereby enhancing thermoelectric performance at room temperature.

Contribution

It introduces a novel microstructure manipulation technique using laser surface remelting to improve thermoelectric properties of Heusler compounds.

Findings

Laser remelting creates microstructures with high dislocation density and small grains.

Microstructure manipulation reduces thermal conductivity and electrical resistivity.

Enhanced thermoelectric performance observed at room temperature.

Abstract

There is an increasing reckoning that the thermoelectric performance of a material is dependent on its microstructure. However, the microstructure-properties relationship often remains elusive, in part due to the complexity of the hierarchy and scales of features that influence transport properties. Here, we focus on the promising Heusler-Fe2VAl compound. We directly correlate microstructure and local properties, using advanced scanning electron microscopy methods including in-situ four-point-probe technique for electron transport measurements. The local thermal conductivity is investigated by scanning thermal microscopy. Finally, atom probe tomography provides near-atomic scale compositional analysis. To locally manipulate the microstructure, we use laser surface remelting. The rapid quenching creates a complex microstructure with a high density of dislocations and small, elongated grains. We hence showcase that laser surface remelting can be employed to manipulate the microstructure to reduce the thermal conductivity and electrical resistivity, leading to a demonstrated enhancement of the thermoelectric performance at room temperature.