X線に依る銅合金樹状晶の組成に及ぼす焼鈍の影響に關すろ研究

Abstract

The effect of annealing upon the compositions of dendrites of tin bronze was studied by X-ray back reflection method and microscopic analysis. X-ray patterns have shown broad lines and bands, the former corresponding to the boughs and twigs of the dendrites and the latter to the fillings. The composition of the inner boughs, which were determined from the lattice constans, is richer in tin than those of the outer ones but in the fillings above relations are reversed; i.e, for an alloy having 9.1 % Sn the inner boughs corresponds to 5.3_??_7.0% Sn and the outer to 4.6_??_6.1% and the fillings to 7.0_??_13.3% and 6.1_??_11.9% respectively, and the outer parts contain more δ or η. The tin-rich parts of the fillings are consumed by peritectic reactions, and hence, the outer parts have no tin rich solid solutions. When these alloys are annealed, tin-rich parts of the fillings gradually disappear, and at 700° the alloys will have almost a homogeneous structure. In α-brass, as the temperature difference between the solidus and the liquidus is not very large and the atomic diameter of Zn is not also much larger than that of Cu, the band corresponding to the fillings of the dendrites becomes narrow, and hence the lines and the bands combine into broad lines. The composition of alloys having 17.2% and 26.6% Zn has shown ranges of 13.8_??_23.9% and 21.8_??_31.8 % Zn respectively, and the latter contained β-phase of 32% Zn which is formed by a peritectic reaction.