THE REDUCTION OF DENDRITE ARM SPACING USING A NOVEL PRESSURE-ASSISTEDINVESTMENT-CASTING APPROACH

Dendritic structures are the predominant microstructural constituents of solidified alloys. The primary, and more often the secondary, dendr ite arm spacings control the segregation pattern that largely determin es the properties of the material. It is advantageous to refine the de ndritic arm spacing (DAS) in castings. In this respect, there is a tec hnological advantage to refine the DAS in conventional investment cast ing. In this paper, the authors describe a newly developed pressure-as sisted investment casting process which produces lower DAS values in c ast LM25 alloy as compared to those of the conventional investment cas ting process. The values of DAS obtained in this process were, however , much higher than those of the squeeze-casting process. (C) 1997 Else vier Science S.A.