Cu-13.1 at%Be-0.2 at%Co合金の時効におよぼす急冷凝固の影響

抄録

A Cu-13.1 at%Be-0.2 at%Co crystalline alloy was directly produced by rapid solidification and then aged. Rapidly solidified foils about 250±50 μm in thickness were obtained by an piston-anvil type apparatus. The structure changes are investigated by means of micro-Vicker’s hardness (Lood, 2.94N), X-ray diffraction and electron microscopy. The rapid-solidification (R.S.) induces a low maximum hardness and prolongs the time necessary to attain the maximum hardness below 723 K, contrary to our experimental results for Cu-Ti⁽¹⁾ and Ni-Ti⁽²⁾ alloys. The Johnson-Mehl kinetic modes (n)⁽³⁾ of aging are about one for the R.S. alloy and about two for a commercially produced (C.P.) alloy below 723 K. The precipitation mechanism of the R.S. alloy is constructed by the preferencial fine precipitation of γ phase instead of γ′ phase. The dominant factor of age-hardening for the R.S. alloy is mainly the dispersion hardening mechanism of fine γ phase particles instead of the precipitation hardening of γ′ phase for the C.P. alloy.