Thermal Transport and Thermal Diffusivity by Laser Flash Technique: A Review

Thermophysical properties encompassing specific heat, thermal conductivity, thermal diffusivity and thermal expansion and their temperature dependence is most sought after during selection of materials for various engineering applications. In this review a broad perspective on the thermal transport in metals and alloys, thermal energy carriers and factors affecting their mean free path is presented. Following the discussion on thermal transport, various techniques available for measuring thermal diffusivity, their principle of detection, merits and demerits are deliberated with an emphasis on laser flash analyzer. Theory of laser flash analysis, possible causes for deviation in the theoretical assumptions that affect the accuracy of measured diffusivity and ways and means of improving the same is dwelt upon. Finally, few typical case studies on thermal diffusivity measurements covering broad spectrum of materials differing in chemistry, degree of deformation, and heat treatment conditions are presented to demonstrate the sensitivity of thermal diffusivity to microstructural changes in materials.