Microstructural evolution during spray forming of an Al-18Si alloy

Spray forming of Al-18Si alloy and its behaviour in semi-solid state holding has been studies.It is observed that a smaller deposition distance leads to large scale compositional inhomogeneity in the preform.
This effect is attributed to increased incoming fraction of liquid at the deposition surface with growing thickness of the deposit. A large liquid pool thickness leads to development of microstructure with a typical characteristics of conventional casting process. A uniform
microstructure is evolved when the thickness of liquid pool is comparable to the thickness of the interaction
domain formed during spray deposition.