Effect of hierarchically distributed nano-to microscale skutterudite inclusions on the lattice thermal conductivity of TiNiSn-based half-Heusler alloys

• Published in: Journal of alloys and compounds 2018-01, Vol.732, p.928-934
• Main Authors: Tarkhanyan, Roland H., Niarchos, Dimitris G.
• Format: Article
• Language: English
• Subjects: Alloys; Half-Heusler alloys; Heat conductivity; Heat transfer; Heusler alloys; Inclusions; Nanocomposite; Nanocomposites; Random distribution; Skutterudite inclusions; Studies; Thermal conductivity; Thermoelectric materials; Thermoelectricity
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2017.10.185

The goal of this work is an investigation of the reduction in lattice thermal conductivity of a Heusler alloy by introducing inclusions in a host matrix with initially high thermal conductivity. Using panoscopic hierarchical architecture approach and assuming Gamma-distribution for spherical inclusions of different size, a general expression is found for the effective lattice thermal conductivity of a two-phase thermoelectric material in “gray medium” approximation. As an application of this analytical expression, it is shown that the introduction of nano-sized skutterudite inclusions into the half-Heusler matrix can drastically reduce lattice thermal conductivity of the composite structure. Due to this effect, significantly higher ZT values can be achieved in the half-Heusler alloys at 300–700 K. •Effect of nanoscale inclusions on lattice thermal conductivity (LTC) of a composite is examined.•General analytical expression for LTC of 2-phase composites is found.•Introduction of CoSb3 inclusions into half-Heusler TiNiSn drastically reduces the LTC.•The reduction in LTC increases monotonically with increasing of the volume fraction.•The reduction is the larger the smaller is the average size of the inclusions.