Semi-solid deformation of non-dendritic structures .1. Phenomenological behavior

Semi-solid deformation mechanisms are proposed to be four major mechanisms: liquid/flow (LF); flow of liquid incorporating solid particles (FLS); sliding between solid particles (SS); and plastic deformation of solid particles (PDS) mechanisms. The segregation phenomenon during semi-solid deformation, in which the solid particles segregate in the center portion, while the liquid segregates around the edge, is predicted by the phenomenological model. As the solid fraction and the deformation rate increase, the SS and PDS mechanisms become more dominant, as predicted by the phenomenological model. At small deformation strain, the center area dominated by the SS and PDS mechanisms is smaller for lower deformation rate than that for higher deformation rate; however, as the deformation strain increases, the situation is reversed, which is due to the composite deformation rate effects predicted by the phenomenological model. The effects of the deformation temperatures and deformation rates will be discussed in Part II, based on the present framework. (C) 1997 Acta Metallurgica Inc.