Effect of Ball-Milling on Sinterability of Si-Ge Powders Prepared by Gas Atomization of the Corresponding Melts

Each p- and n-type powder of Si0.8Ge0.2 for thermoelectric elements was prepared by gas atomization of the corresponding melts. Then, the relationship between the characteristics of Si-Ge powders and their sinterability was studied. Particular emphasis was placed upon understanding the effect of ball-milling on the sinterability of the as-prepared powders. The composition of the as-prepared powder was different from the batch composition due to melting and evaporation of the dopant above 1550K. Ball-milling made the particle size of the as-prepared powders small, presumably together with introducing distortion to the crystal lattice. Densification of as-prepared powders was abruptly promoted above 1500K by a pulse-current sintering; however, this densification temperature of the powders after ball-milling was lowered by approximately 100K. The grain size and elemental inhomogeneity of the dense body after sintering were also reduced by ball-milling process.