固・液共存相を伴う凝固における実効分配係数の解析 : 固相内拡散および濃度境界層を考慮する場合

概要

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The effective distribution coefficients for solidification proposed hitherto are classified according to the morphology and the solidifing condition. In this paper, two cases for the solidification accompanied with a liquid and solid region have been theoretically analyzed by taking account of the diffusion in solid phase (case XII) or the diffusion boundary layer in front of the liquid and solid region (case XIV). In these cases, four kinds of effective distribution coefficient which were defined in the previous paper are represented by the theoretical formula. The representative effective distribution coefficient (K^*_3), which is the solid composition divided by bulk liquid composition, is formulated in the both cases as follows : K^*_3=K{1-A/(Le){2-K(1+τ)}-2} case XII K^*_3={1+1-exp(-Rδ/D_l)/Le(1-K/2)-1・AK/2}K/K+(1-K)exp(-Rδ/D_l)-AK/(Le)(2-K)-2 case XIV Furthermore, by the use of the analytical results, the data concerning the macrosegregations in unidirectionally solidified Al-Ag alloys reported by the other authors are analyzed. The theoretical results have been in good agreement with the experimental data. In comparison with the two extreme cases for diffusion coefficients in solid phase, D_s=0 and D_s=∞, in the solidification accompanied with liquid and solid region, the effects of the diffusion in solid phase are given quantitatively.
1979-02-01