微小重力下での Sn-Pb 共晶系合金の凝固

抄録

Solidification mechanisms of hypo-eutectic, eutectic, and hyper-eutectic alloys under the microgravity conditions and formation mechanisms of gravitational segregation on earth are consi­dered. Experiments are performed by using the Sounding Rocket TR-1A 4. Six samples of Sn-Pb eutectic alloys containing 35, 38.1 and 39 mass%Pb are used. Two series of experiments are per­formed; Samples which are melted before launching are solidified under the microgravity conditions and others are melted and solidified under the microgravity conditions. Each sample occurs undercooling before the eutectic solidification. Granular crystals of primary Pb disperse homogeneously throughout the samples under the microgravity conditions. No gravitational segregation of samples appear under the microgravity conditions. Dendrite arms are detached by release of the latent heat during recalescence of undercooling and solidification.