TY - JOUR
T1 - Influence of Mg on Solidification of Hypereutectic Cast Iron
T2 - X-ray Radiography Study
AU - Yamane, K.
AU - Yasuda, Hideyuki
AU - Sugiyama, A.
AU - Nagira, T.
AU - Yoshiya, M.
AU - Morishita, K.
AU - Uesugi, K.
AU - Takeuchi, A.
AU - Suzuki, Y.
N1 - Funding Information:
This study was supported by a Grant-in-Aid for Scientific Research (S) from MEXT (No. 24226018). The synchrotron radiation experiments were performed as general projects at beamlines of BL20XU and BL20B2 at SPring-8 (JASRI).
Publisher Copyright:
© 2015, The Minerals, Metals & Materials Society and ASM International.
PY - 2015/11/1
Y1 - 2015/11/1
N2 - Radiography using a synchrotron radiation X-ray source was performed to examine solidification and melting behaviors in hypereutectic cast iron specimens containing 0.002 and 0.05mass pctMg. The solidification sequence in the alloy containing 0.002mass pctMg was (1) nucleation and growth of graphite particles of which transformed to a flake-like shape, (2) growth of γ-Fe dendrites, (3) nucleation of graphite particles ahead of the interface just prior to the eutectic solidification, and (4) the eutectic solidification. In contrast, (1) and (2) occurred nearly at the same time in the specimen containing 0.05 mass pct Mg. The addition of 0.05mass pctMg significantly reduced the temperature range in which the graphite particles grew as the primary phase. Image-based analysis of melting behavior showed that even 0.05 mass pct addition was sufficient to modify the phase equilibrium of the liquid, γ-Fe, and graphite phases. Thus, the observed influence of Mg on the solidification sequence was attributed to the modification of the phase equilibrium. The influence was consistently explained by considering the shift of the eutectic composition to the carbon side in the pseudo-ternary system. It was also suggested that supersaturation of carbon in the melt increased as the temperature decreased even though the primary graphite particles existed. The supersaturation may cause the nucleation of the graphite particles just before the eutectic solidification.
AB - Radiography using a synchrotron radiation X-ray source was performed to examine solidification and melting behaviors in hypereutectic cast iron specimens containing 0.002 and 0.05mass pctMg. The solidification sequence in the alloy containing 0.002mass pctMg was (1) nucleation and growth of graphite particles of which transformed to a flake-like shape, (2) growth of γ-Fe dendrites, (3) nucleation of graphite particles ahead of the interface just prior to the eutectic solidification, and (4) the eutectic solidification. In contrast, (1) and (2) occurred nearly at the same time in the specimen containing 0.05 mass pct Mg. The addition of 0.05mass pctMg significantly reduced the temperature range in which the graphite particles grew as the primary phase. Image-based analysis of melting behavior showed that even 0.05 mass pct addition was sufficient to modify the phase equilibrium of the liquid, γ-Fe, and graphite phases. Thus, the observed influence of Mg on the solidification sequence was attributed to the modification of the phase equilibrium. The influence was consistently explained by considering the shift of the eutectic composition to the carbon side in the pseudo-ternary system. It was also suggested that supersaturation of carbon in the melt increased as the temperature decreased even though the primary graphite particles existed. The supersaturation may cause the nucleation of the graphite particles just before the eutectic solidification.
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U2 - 10.1007/s11661-015-3077-z
DO - 10.1007/s11661-015-3077-z
M3 - Article
AN - SCOPUS:84942986516
SN - 1073-5623
VL - 46
SP - 4937
EP - 4946
JO - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
JF - Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
IS - 11
ER -