Segregation behavior of ADC12 alloy differential support formed by near-liquidus squeeze casting

• A new method, near-liquidus squeeze casting was developed.
• The segregations of different positions and selected sections were studied.
• One image of continuous microstructures of 3 mm long was obtained.
• Illustration of segregation across section of great wall thickness was obtained.
• Increase of cooling rate can eliminate center segregation.

Near liquidus squeeze casting, a new technology of squeeze casting, can form globular structure without preparation of semi-solid slurries or billets at near liquidus pouring temperature. In this paper, the segregation behavior at different positions and across the selected section of ADC12 alloy differential support formed by near-liquidus squeeze casting are investigated. The results show that at different positions, different cooling rates result in different segregation characteristics, and different element contents lead to different microstructure and Vickers hardness. Overall, the thin walled position has the best microstructure compared with other positions of differential support. Segregations occur mostly at edge and center regions on the selected section. The 3 mm width edge region has gradual change of element contents, microstructure and Vickers hardness. The center region is the maximum segregation region across the section. Compared with the region around, it has bigger difference of element contents, different microstructure and Vickers hardness. As the cooling rate of center region increases, the area of center segregation decreases and eventually disappears. Design for thinner wall thickness and appropriate mold cooling system could eliminate the center segregation.