Evolution of Macrosegregation During Directional Solidification of Binary Alloys

Abstract

Various causes of macrosegregation during solidification of alloys, and important findings from investigations by the present authors on role of material parameters, permeability of the mushy region and cooling rate have been reviewed, and important results presented. The investigations consisted of mathematical model development and controlled experiments. The role of material parameters on macrosegregation was analyzed through comparative study of three alloy systems, viz., ammonium chloride-water, iron-carbon and lead-tin. The effect of cooling rate on thermosolutal convection and macrosegregation in iron-carbon system was highlighted through a series of numerical simulations. Some highlights of controlled experiments on vertical solidification of lead-tin alloys, and its analysis with the help of the mathematical model are presented.

Keywords:

• Solidification
• macrosegregation
• mathematical modeling
• binary alloys
• permeability

Acknowledgements

This work was carried out under grants from Department of Science and Technology, New Delhi (Grant No. III 5(19)/96-ET) and Indo-French Centre for Promotion of Advanced Research, New Delhi (Grant No. 1608-I). The authors are thankful to Professor R. Balasubramaniam, IIT Kanpur for many useful discussions and suggestions. The authors gratefully acknowledge the support, encouragement and suggestions form Professor E. C. Subbarao, Senior Advisor, Tata Consultancy Services and Professor Mathai Joseph, Executive Director, Tata Research Development and Design Centre.

Notes

^*Present address: Birla Management Corporation Limited, Mumbai, 400093 India

^**Present address: Flat 3C, ‘Shatabdi,’ 54/2/1/1/1, Andul Road, Howrah 711109, India