일방향 응고시 샘플회전에 의한 Pb-Sb 합금의 Pb 수지상 구조의 변화

The Change of Pb Dendritic Structure of Pb-Sb Alloys due to Sample Rotation during Directional Solidification

The various mechanical a n d physical properties of metallic materials made through directional solidification w a s closely related to the solidified microstructure as a function of directional solidification parameters such as growth velocity, temperature gradient a n d alloy composition. Besides these parameters, the sample rotation in conjunction with directional solidification was used as another novel solidification parameter in order to reduce the effect of earth gravity. Therefore, this study was performed to investigate the change of primary Pb dendritic microstructure in P b ~ 1 0 w t % S b and P b - 5 . 8 w t % S b alloys directionally solidified vertically upwardat 3 n m / s growth velocity with the sample rotation. These alloys showed the uniform microstructure of primary P b dendrites within eutectic matrix without sample rotation while, as sample rotation increased, the secondary dendrite arms were underdeveloped, the dendrite a r m spacings were reduced and the nonuniform microstructures were obtained.