Cu-Ni-Si三元全系平衡状態の研究(第4報)

Abstract

The alloys of the ternary system copper-nickel-silicon are very useful industrially, such as Silicon Monel, Corson Alloy, etc., but the ternary system has not been studied systematically. By means of microscopic examination and thermal, X-ray and dilatometric analyses the author has investigated the equilibrium state of the whole system, a part of which is reported in this paper. Since γ phase of the copper-silicon system is formed on cooling by the peritectoid reaction κ+δ→γ at 730°, it does not maintain equilibrium with liquid, However, when nickel is added to this binary system, the γ phase dissolves nickel and forms a ternary solid solution, which crystallizes primarily on cooling from liquid containing nickel more than 2% by weight. In general, for the requirement of the primary crystallization of a phase, which does not maintain equili-brium with liquid in a binary system, from ternary liquid on addition of the third constituent, the nonvariant reactions except the following one are not considered to exist: remelting and eutectoid reaction s1→L1+s2+s3 or remelting and peritectoid reaction s1+s2→L1+s3 both on cooling, where s and L indicate solid and liquid respectively. In the heterogeneous equilibrium of the ternary system containing small amount of nickel with respect to the liquid, the every remelting reaction as above shown does not occur, and the peritecto-eutectoid reaction β+γ_??_κ+δ (795°_??_793°, 1_??_1.3% Ni, 8% Si) can be presumed to exist from the behaviour of the monovariant reactions β_??_κ+δ and κ+δ_??_γ starting from the copper-silicon system, The preceding experimental results with the theoretical consideration lead to the conclusion that γ phase is primarily crystallized without such remelting reactions from ternary liquid. The process in which the primary crystallization of γ phase takes place is as follows: - in Fig 13 (quanti-tative diagram) or in Fig. 18 (qualitative diagram) L+α+γ_??_β……T1' point (858°, 89.5% Cu, 2.5% Ni, 8.0% Si) and L+β+γ_??_δ……T2' point (835°, 89.0% Cu, 2.0% Ni, 9.0% Si) In these reactions, when L is consumed, β→α+γ for the former and β+γ→δ for the latter on cooling. The monovariant curves β→α+γ and α+β→κ meet at B2', where the monovariant reaction α+β→κ+γ occurs. If β, κ and γ are in coexistence after the completion of the latter reaction, the reaction of β→κ+γ takes place. The reactions B→κ+γ and β+γ→δ form the following reaction, [β]B3'+[γ]C4'→[κ]J2'+[δ]D5'……B'3 point (795°_??_793°, 1_??_1.3% Ni, 8.0% Si) When γ is consumed in the preceding reaction, β→κ+δ may take place, and if β be consumed κ+δ→γ occurs, and these two monovariant reactions fall into the respective nonvariant reaction in the copper-silicon system.