(09)On the Formation of Dispersed Microstructures in Fe-Cu based Metastable Liquid-Liquid Phase Separated Powders via Rapid Solidification

摘要

A fine dispersion of Cu-rich particles in an Fe-rich matrix is a desirable microstructure in the Fe-Cu system for modeling dispersion strengthening and conductivity effects in consolidated powder microstructures. Previous work has shown that this microstructure can be difficult to achieve since the metastable miscibility gap is often inaccessible during a conventional solidification process, which causes a common dendritic iron structure to from with copper interdendritic regions. Small scale atomization experiments were carried out in several Fe-Cu alloys by using a pressurized crucible to expel the superheated melt through a small orifice into a short free fall in a gas environment, followed by capture in quenching oil. Microstructure analysis by SEM of the resulting powders helped to gain insight to the solidification pathway taken by the rapidly solidified droplets. Micro-hardness was also used to further characterize mechanical properties of the as-solidified powders.