TY - JOUR
T1 - A real-time synchrotron X-ray study of primary phase nucleation and formation in hypoeutectic Al-Si alloys
AU - Prasad, Arvind
AU - McDonald, Stuart D.
AU - Yasuda, Hideyuki
AU - Nogita, Kazuhiro
AU - StJohn, David H.
N1 - Funding Information:
We gratefully acknowledge financial support from Australian Research Council (ARC) Discovery Grant (Project ID: DP120101672 ), the Centre for Advanced Materials Processing and Manufacturing (AMPAM) at the University of Queensland (UQ), UQ-Nihon Superior (NS) collaborative research program , and the Australian Synchrotron international synchrotron access program (Project ID: AS/IA123/5664 and AS/IA124/6235 ). This work is also supported in part by a Grant-in-Aid for Scientific Research (S) (Project ID: 24226018 ) from Japan Society for the Promotion of Science (JSPS), Japan . In-situ observation experiments were performed at the SPring-8 BL20B2 and BL20XU (Project ID: 2012A1192, 2012B1430, 2014A1540 and 2014A1541). The authors thank Prof. H. Yasuda׳s research group, Dr. T. Nagira and Mr. N. Nakatsuka of Osaka University, Mr. Guang Zeng of UQ, Dr. A. Takeuchi and Dr. Y. Suzuki of the SPring-8 synchrotron for the in-situ observations at SPring-8 BL20B2 and BL20XU.
Publisher Copyright:
© 2015 Elsevier B.V. All rights reserved.
PY - 2015/11/15
Y1 - 2015/11/15
N2 - This work reports the results of real-time X-ray radiography of grain refined and unrefined Al-Si alloys solidified at the SPring-8 synchrotron. The nucleation events were observed and the grain density and growth rate following nucleation were measured. Nucleation of the grain refined alloy samples occurred from the coolest to the hottest parts of the field of view in a sequence that mimicked a forward moving wave. No additional nucleation events occurred between the first nucleated grains and there was no evidence of grains being generated by fragmentation. Measurements of both grain density and growth rate show the effect of Si content and grain refiner (Al3Ti1B master alloy) additions on grain size. While the total number of grains increases in the alloys with added Al3Ti1B master alloy, the growth rates tend to be slower. Furthermore, the growth rate for all alloy compositions fluctuates between slow and fast velocities during the initial stages of growth and then tends towards a low steady state value. This decreasing trend is explained in terms of thermal and solutal field interactions between adjacent growing grains and subsequent grain impingement. These measurements result in a better understanding of the role of nucleation and solute content in influencing further nucleation and the subsequent change in the solid-liquid growth rate.
AB - This work reports the results of real-time X-ray radiography of grain refined and unrefined Al-Si alloys solidified at the SPring-8 synchrotron. The nucleation events were observed and the grain density and growth rate following nucleation were measured. Nucleation of the grain refined alloy samples occurred from the coolest to the hottest parts of the field of view in a sequence that mimicked a forward moving wave. No additional nucleation events occurred between the first nucleated grains and there was no evidence of grains being generated by fragmentation. Measurements of both grain density and growth rate show the effect of Si content and grain refiner (Al3Ti1B master alloy) additions on grain size. While the total number of grains increases in the alloys with added Al3Ti1B master alloy, the growth rates tend to be slower. Furthermore, the growth rate for all alloy compositions fluctuates between slow and fast velocities during the initial stages of growth and then tends towards a low steady state value. This decreasing trend is explained in terms of thermal and solutal field interactions between adjacent growing grains and subsequent grain impingement. These measurements result in a better understanding of the role of nucleation and solute content in influencing further nucleation and the subsequent change in the solid-liquid growth rate.
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U2 - 10.1016/j.jcrysgro.2015.06.024
DO - 10.1016/j.jcrysgro.2015.06.024
M3 - Article
AN - SCOPUS:84941703163
VL - 430
SP - 122
EP - 137
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
SN - 0022-0248
ER -