高鉛青銅の凝固時における錫の挙動

抄録

  The redistributing behaviors of tin in the Cu-20%Pb-2 or 5%Sn bronzes during freezing wered etermined by means of the X-ray microanalysis. Cosiderable release of tin from the alpha solid during freezing results in extreme condensation in the remained liquid as much as 20% at the end of the monotectic reaction. The ratios tin concentration in the solid to that in the liquid are 0·08 to 0.13 and 0.14 to 0.20 respectively in the Cu-20%Pb-2 and 5%Sn bronzes and are the least at the initial stage of nucleation for alpha dendrites. The growing alpha solid is often surrounded with the (L₁+L₂) liquid. The lead-rich L₂ phase which is easily aggregated leads to coarse and irregular distribution of lead. Tin once condensec in the liquid is inversely released from the lead-rich liquid and disolved into the alpha solid accompanying with coring in it. Less condensation of tin in the remained liquid is found in the bronzes containing 2% nickel and silver. 0.5% silicon has an inverse effect.