Effect of Cooling Rate on Iron-rich Intermetallic Phases in 206 Cast Alloys

摘要

The effect of cooling rate on the solidification characteristics ofthe iron-rich intermetallics in 206 cast alloys with iron contents upto 0.5 wt% was investigated. The iron-rich intermetallics wereanalyzed and characterized by using Scanning ElectronMicroscopy (SEM), Differential Scanning Calorimeter (DSC) andThermal Analysis (TA). It was found that Chinese script α-Fe andplatelet β-Fe phases are the two main iron-rich intermetallics up to0.3 wt% Fe. With increasing cooling rate, the precipitatetemperature increases for α-Fe but decreases for β-Fe andeventually the formation of the β-Fe will be completelysuppressed. At 0.5 wt% Fe, two extra iron-rich intermetallics,Chinese script Alm(FeMn) and platelet Al3(FeMn) areexperimentally observed. With increasing cooling rate, theAl3(FeMn) or Al_6(FeMn) phases that precipitated at relatively lowcooling rate can be replaced by Al_m(FeMn) and α-Fe. The criticalcooling rate to effectively suppress the formation of the platelet β-Fe and obtain dominant Chinese script α-Fe or Al_m(FeMn)decreases with increasing iron level.