| Title |
Microstructural Evolutions in Hypereutectic Al-Si Alloy During Spray Forming and Extrusion |
| Authors |
김상균(S . K . Kim) ; 석현광(H . K . Seok) ; 이재철(J . C . Lee) ; 이호인(H . I . Lee) ; 라형용(, H . Y . Ra) |
| Abstract |
Microstructural evolutions of both Si particles and matrix grains of hypereutectic Al-Si alloy were investigated by calculating temperature profiles within the preform during spray forming. Based on calculations, the cooling rates were observed to be relatively higher both at the bottom and the top than the inner regions of the preform along the rotation axis of rod. Such trends in temperatures resulted in size variations of Si particles within the preform. The size of Si particles varies from 3㎛ to 13.5㎛ with distance from the surface to the inner of the preform along the rotation axis of rod. Larger Si particles observed from the inner regions of the preform were found to be poly-crystals having irregular surface boundaries. However, such Si particles were fractured after extrusion, indicating a possibile means for fabricating hypereutectic Al-Si alloys with fine Si particles. In addition, the methodology for predicting the matrix grain size in the presence of small Si particles was also demonstrated. |