Yukinori Ono1, Tsutomu Takechi1, Noriko Murai1 and Keisaku Ogi1
1Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka
The partition coefficients of chromium and carbon to primary austenite were determined on Fe-Cr-C ternary alloys containing 1.1 to 3.6 mass%C and 1.5 to 25.5 mass%Cr. The specimens were held for 3.6 ks just below the liquidus temperature, and the mixtures of liquid and solid were quenched onto a copper chill plate. Chromium and carbon contents of primary austenite (CSCr, CSC) and those of quenched liquid (CLCr, CLC) were analyzed with EPMA, and the partition coefficients (kCr and kC) were evaluated as CSCr/CLCr and CSC/CLC. To avoid the influence of contamination in EPMA analysis, the C content was measured on the fresh surface of the specimen moving at a constant rate of 60 μm/min.
kCr decreased from 0.80 to 0.53 mainly with the increase in carbon content of the alloy, while kC decreased from 0.38 to 0.25 with the increase in chromium content. The content of Si from 0.19 to 0.25 mass% dissolved into liquid from the crucible (46 mass%Al2O3, 50 mass%SiO2) little influenced both kCr and kC.
partition coefficient, iron-chromium-carbon alloy, solidification, cast iron, austenite, phase diagram
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