三维网络SiC/Cu金属基复合材料的凝固显微组织

用挤压铸造法制备了三维网络SiC/Cu金属基复合材料,研究了铸造压力、网络SiC骨架预热温度、浇注温度等工艺条件对复合材料凝固显微组织的影响.结果表明,三维网络SiC陶瓷骨架在晶体生长和结晶过程中有重要作用,在一定条件下在网孔内可形成垂直于骨架表面的枝晶网络,或形成粒度细小且分布均匀的等轴晶组织;骨架的孔径对显微组织的影响也很大,细小的孔径有利于晶粒细化和组织均匀化,粗大的孔径助长宏观偏析和铅的偏聚.骨架减轻了复合材料中锡的反常偏析,使锡的偏析主要发生在骨架表面附近的微小区域,从而避免了在铸件表层的集中偏析.

Solidification microstructure of 3D--meshy SiC/Cu metal matrix composites

3D-meshy SiC/Cu metal matrix composite was fabricated by squeeze casting process. The influence of process conditions on solidification microstructure of the composites was studied. The results showed that 3D-meshy SiC ceramic skeleton played an important role during the solidification of the matrix and the course of crystal growth and crystallization. Under the certain conditions, the dendrites perpendicular to skeleton surface appeared, and the fine and even equiaxed grains structure formed. The influence of skeleton apertures on microstructure was very remarkable. The fine apertures were benefit to grain refining and structure uniformity, while big apertures were apt to produce macroscopic segregation and concentration of plumbum. The tin inverse segregation was lightened for the SiC skeleton, because tin was gathered in a very narrow region near the surface of skeleton, which avoided tin mass segregation in the surface layer of the cast.