Phase Transformation and Thermoelectric Properties of Fe0.92Mn0.08Si2 Prepared by Mechanical Alloying

Abstract

In an attempt to enhance phase transformation and homogenization of Mn-doped , mechanical alloying of elemental powders was applied. Cold pressing and sintering in vacuum were carried out to produce a dense microstructure, and then isothermal annealing was employed to induce a phase transformation to the -semiconductor. Phase transitions in this alloy system during the process were investigated by using XRD, EDS and SEM. As-milled powders after 100 h of milling were shown to be metastable state. As-sintered iron silicides consisted of untransformed mixture of -and -FeSi phases. -phase transformation was induced by subsequent isothermal annealing at , and near single phase of -was obtained after 24 h of annealing. Thermoelectric properties in terms of Seebeck coefficient, and electrical conductivity were evaluated and correlated with phase transformation. Seebeck coefficient electrical resistivity and hardness increased with increasing annealing time due to phase transformation.