Metallurgical and Materials Transactions A

, Volume 46, Issue 9, pp 4160–4173 | Cite as

In Situ Study of Microstructure Evolution in Solidification of Hypereutectic Al-Si Alloys with Application of Thermal Analysis and Neutron Diffraction

  • Dimitry G. SediakoEmail author
  • Wojciech Kasprzak


Understanding of the kinetics of solid-phase evolution in solidification of hypereutectic aluminum alloys is a key to control their as-cast microstructure and resultant mechanical properties, and in turn, to enhance the service characteristics of actual components. This study was performed to evaluate the solidification kinetics for three P-modified hypereutectic Al-19 pct Si alloys: namely, Al-Si binary alloy and with the subsequent addition of 2.8 pct Cu and 2.8 pct Cu + 0.7 pct Mg. Metallurgical evaluation included thermodynamic calculations of the solidification process using the FactSage™ 6.2 software package, as well as experimental thermal analysis, and in situ neutron diffraction. The study revealed kinetics of solid α-Al, solid Si, Al2Cu, and Mg2Si evolution, as well as the individual effects of Cu and Mg alloying additions on the solidification path of the Al-Si system. Various techniques applied in this study resulted in some discrepancies in the results. For example, the FactSage computations, in general, resulted in 281 K to 286 K (8 °C to 13 °C) higher Al-Si eutectic temperatures than the ones recorded in the thermal analysis, which are also ~278 K (~5 °C) higher than those observed in the in situ neutron diffraction. None of the techniques can provide a definite value for the solidus temperature, as this is affected by the chosen calculation path [283 K to 303 K (10 °C to 30 °C) higher for equilibrium solidification vs non-equilibrium] for the FactSage analysis; and further complicated by evolution of secondary Al-Cu and Mg-Si phases that commenced at the end of solidification. An explanation of the discrepancies observed and complications associated with every technique applied is offered in the paper.


Neutron Diffraction Solidus Temperature Solidification Path Engine Block Hypereutectic Alloy 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The authors would like to thank Renata Zavadil for assistance with metallographic work and Marta Aniolek MSc. Eng. for thermal analysis experiments. Financial support of the Materials for Energy End Use in Transformation Program of Natural Resources Canada is gratefully acknowledged. Studies completed at the Canadian Neutron Beam Centre (CNBC) were partially sponsored by the Natural Sciences and Engineering Research Council of Canada (NSERC). We gratefully acknowledge contributions made to this study by Drs. Ovidiu Garlea and Clarina de la Cruz, Oak Ridge National Laboratories. Moreover, we thank Ibrahim Sadiq and Matthew Li from University of Waterloo for their help with experimental data processing and graphical data representation during their co-op terms correspondingly at CanmetMATERIALS and CNBC.


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Copyright information

© Published with permission of Her Majesty the Queen in Right of Canada, as represented by the Minister of Natural Resources 2015

Authors and Affiliations

  1. 1.Canadian Neutron Beam CentreChalk RiverCanada
  2. 2.CanmetMATERIALS, Natural Resources CanadaHamiltonCanada

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