Structural parameters as grain size, dendritic and cellular spacings, segregated products, porosity and Concepção de professores do ensino fundamental sobre a dislexia do desenvolvimento other phases are strongly influenced by the thermal behavior of the metal/mold system during solidification, imposing a close correlation between this and the resulting microstructure.Several unidirectional solidification studies with the objective of characterizing cellular and dendritic spacings have been developed in large scale involving solidification in steady-state heat flow.The main objective of this work is to determine the thermal solidification parameters during the cellular/dendritic transition as well as to compare theoretical models that predict cellular and primary dendritic spacings with experimental results for solidification situations in unsteady-state heat flow.Experiments were carried out in a water cooled unidirectional solidification apparatus and dilute alloys Inductively Coupled Plasma Optical-Emission Spectroscopy Determination of Major and Minor Elements in Vinegar of the Sn-Pb system were used (Sn 1.5wt%Pb, Sn 2.
5wt%Pb and Sn 5wt%Pb).The upper limit of the Hunt-Lu cellular growth model closely matched the experimental spacings.The lower limit calculated with the Hunt-Lu dendritic model best generated the experimental results.The cellular/dendritic transition was observed to occur for the Sn 2.5wt%Pb alloy over a range of analytical cooling rates from 0.
28 K/s to 1.8 K/s.