Fundamental differences between spray forming and other semisolid processes

The distinguished microstructural features of spray formed products are the refined equiaxed grain structure and lower segregation level. Attempts hav e been made in the past to propose mechanisms to explain the formation of e quiaxed grain structure. Recently there has been a tendency in correlating spray forming with other semisolid processes such as liquid phase sintering (LPS) and rheocasting. In this article, the fundamental differences betwee n spray forming and the other semisolid processes are discussed. Results sh ow a unique thermal and solute profile on the deposit surface, resulting fr om the mixing of rapidly solidified metal formed during atomization and the solute-poor liquid formed by addition of the liquid of alloy composition, which contributes mainly to the microstructural evolution during spray form ing. A simple experiment was designed to give supporting evidence to this v iew. (C) 2001 Published by Elsevier Science B.V.