The conventional method to elaborate bismuth telluride alloys for thermoelectric applications is based on directional solidification by the Bridgman technique. The powder metallurgy approach gives an alternative method to produce these thermoelectric materials following a sequence of carefully controlled operations: mechanical alloying, pressing, sintering, extrusion at high temperature and annealing. This paper describes the evolution of the microstructure through the different stages of the whole process. The alloy is produced from pure bismuth, tellurium and selenium powders by mechanical alloying. The particle size distribution and the homogenization of the composition will be described as a function of the processing parameters. The extrusion process is particularly important since it gives the adequate crystallographic texture necessary to obtain the thermoelectric properties comparable to those measured on single crystals.
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