Abstract
A small amount of borax enhanced the sintering of SUS316L stainless steel powder compacts. The compacts of the -100mesh water-atomized powder with 2mass%Na2B4O7 were sintered at different temperatures in vacuum. SEM micrographs and EPMA or EDX figures of the samples indicate that the silica-based oxide film on the surface of the steel particles has dissolved into the melted flux or borax at 1070K, that Cr2B particles have precipitated from the steel matrix while silicon and manganese have concentrated into the flux following a steel/flux reaction at 1270K, and that a Fe-Cr-B eutectic liquid has been formed and the Cr2B particles have disappeared above 1470K. Sintering at 1620K for 60min resulted in the highest density of compacts with almost no vacant pores. The formation of a Fe-Cr-B eutectic liquid may have caused the enhancement of densification by the capillary-force effect of the liquid.
