Pd添加による珪化鉄のε+α→β変態と焼結の促進 Accelerations of ε+α→βTransformation and Sintering of Iron Silicide by Addition of Pd
FeSi<SUB>2</SUB>(β phase) semiconducting iron silicide, which is expected to be widely used as a thermoelectric material in high temperature environment, is formed below 1259K by the peritectoid reaction of FeSi(ε) and Fe<SUB>2</SUB>Si<SUB>5</SUB>(α) two metallic phases. Because the transformation of ε+α→β caused by this peritectoid reaction occurs considerably slowly, the iron silicide material which is produced by sintering of the powder at temperatures above 1259K has to be isothermally heat-treated for at least 180ks at about 1120K after the sintering so that the transformation occurs completely.<BR>We have found that the transformation was drastically accelerated by the addition of a small amount of Pd in the same way as Cu; the isothermal heat-treatment time necessary for the completion of the transformation was reduced to about 1/60. The sintering time needed for the almost full densification of the powder by pressure DCL sintering (DCL; direct current loading) was also reduced. A hypothesis for the mechanisms was proposed.
粉体および粉末冶金 43(12), 1473-1478, 1996-12-15
Japan Society of Powder and Powder Metallurgy