Hermann, R and Gerbeth, G and Biswas, Kaushik and Filip, O and Shatrov, V and Priede, J (2009) Effect of Varying Melt Convection on Microstructure Evolution of Nd-Fe-B and Ti-Al Peritectic Alloys. In: Phase Transformations in Multicomponent Melts. Wiley-VCH Verlag GmbH & Co. KGaA, pp. 245-261. ISBN 9783527319947

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Abstract

The influence of melt convection on the microstructure during solidification of peritectic Nd-Fe-B and Ti-Al alloys was investigated. Since the magnetic and mechanical properties of these technologically relevant materials depend strongly on the microstructure and especially on the volume fraction of the properitectic phase, there is a growing scientific interest for such an investigation. On the basis of numerical simulation of melt convection modes in an inductively heated metallic melt, novel techniques for the modification of the melt convection were developed. This is the forced rotation technique and a modified floating zone facility equipped with a specially designed double coil system, which enabled the application of additional magnetic fields. The forced rotation technique, in which the crucible rotates with well-defined frequencies, leads in accordance with numerical simulation to a strong reduction of the melt convection depending on the frequency. The volume fraction of the soft magnetic α-Fe phase could be drastically reduced in comparison with the common induction melting accompanied by a simultaneous reduction of the secondary dendritic arm spacing. The floating zone facility with the patented double coil system allows the tailoring of the melt convection over a wide range from nil motion to strong stirring. The microstructure of the investigated Ti-Al alloy changed from dendritic to globulitic morphology under strong stirring, whereas the volume fraction of the properitectic phase increased with increasing stirring. The mechanical properties show a significant increased plastic deformation of the samples solidified under strong stirring. The possible reason for the change in morphology is explained as a result of spherical growth under forced convection. The study of the influence of melt convection on the microstructure formation of peritectic alloys showed the feasibility of tailoring the microstructure and the properties of the resulting alloy by customized melt convection using magnetic fields.

Item Type:	Book Section
Uncontrolled Keywords:	melt convection, peritectic solidification, Nd-Fe-B alloys, Ti-Al alloys
Subjects:	Microstructure and Characterization
Divisions:	Glass
Depositing User:	Bidhan Chaudhuri
Date Deposited:	09 Jun 2016 11:14
Last Modified:	09 Jun 2016 11:14
URI:	http://cgcri.csircentral.net/id/eprint/3493

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