Harusige Tsubakino1, Ryoichi Nozato1 and Hiroyasu Mitani2
1College of Engineering, University of Osaka Prefecture, Sakai
The influence of Co content on the volume fraction of discontinuous precipitation cells has been investigated in Cu-2 wt%Be-Co alloys containing Co from 0.05 to 1.0 wt% by means of metallographic observations. The variation in the volume fraction of discontinuous precipitation cells, cell radius and interlamellar spacing with Co content in the specimens of a given ageing condition, and also the variation in mean grain diameter with Co content have been determined by quantitative metallographic measurements. The results obtained are as follows:
(1) With increasing Co content, the volume fraction of discontinuous precipitation cells first decreases but passes through a minimum at Co content of about 0.2 wt% and then increases.
(2) With increasing Co content, cell radius and interlamellar spacing first decreases and increases, respectively, but they remain almost constant at higher Co content, while mean grain diameter decreases continuously.
(3) At constant Co content, cell radius does not depend on mean grain diameter but the volume fraction of discontinuous precipitation cells increases with decreasing mean grain diameter.
(4) Then it is considered that the change in the volume fraction of the discontinuous precipitation cells at lower and higher Co content will be attributed to decrease in cell radius and mean grain diameter, respectively.
(5) The influence of Co content on cell radius and interlamellar spacing will be correlated to the equilibrium phase diagram of Cu-Be-Co ternary alloy in view of the driving force for cell growth.
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