| To examine the influences of vibration and the duration of vibration on the grain refinement, gravity segregation of lead, leakage of lead and hardness, the 60 cps vibration was given to the melt of Cu-Pb alloy during solidification. Results obtained from this study can be summarized as follows ; (1) As the content of lead increases from 10% to 20%, 30%, the ratio of the number of grains per unit area decreases from 2.78 to 2.54, 1.36 in the slowly-cooled structure, and the ratio decreases from 24.80 to 4.37, 1.90 in the rapidly-coolded structure, i.e. the vibration has an effect on the grain refinement in case of low Pb alloy, especially in the rapidly-cooled structure. (2) In case of slow-cooling, the vibration can suppress or eliminate the amount of gravity segregation of lead, and can increase the hardness. (3) The influence on the grain refinement occurs only in the period from 1010℃ to 980℃ during which the dendrites begin to form in Cu-20%Pb alloy. |
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