The nature of dislocations and effect of order in rapidly solidified Fe-(5.5-7.5)wt.%Si alloys

Raviprasad, K and Aoki, K and Chattopadhyay, K (1993) The nature of dislocations and effect of order in rapidly solidified Fe-(5.5-7.5)wt.%Si alloys. In: Materials Science and Engineering A, 172 (1-2). pp. 125-135.

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Abstract

The results of an investigation on the nature of dislocations in rapidly solidified Fe-(5.5–7.5)wt.%Si has been presented as a function of the ordered state achievable during rapid solidification processing. The comparative study involves three rapid solidification processing routes for each alloy: melt spinning, planar flow casting and twin rolling. It is shown that for Fe-5.5wt.%Si alloy, ordering can be completely suppressed, while, in Fe-6.5wt.%Si alloy, the B2 ordering cannot be suppressed. The $DO_3$ state is present in twin-rolled Fe-wt.%Si alloy while, in rapidly solidified Fe-7.5wt.%Si alloy, it is the predominant ordered state. The disordered Fe-5.5wt.%Si alloy contains dislocation dipoles and vacancy loops, while rapidly solidified samples of Fe-6.5wt.%Si composition exhibit B2 order with $a_0/2<111>$type superdislocations where $a_0$ is the $DO_3$ lattice parameter. The paper reports the first observation of a four dislocation set in Fe-Si alloys with the superdislocation burgers vector $a_0<111>$. They are predominantly of mixed type, with some in edge orientation. Analysis of the experimental superdislocation separations in terms of existing models of interaction energies is presented. It is shown that separations reflect the non-equilibrium order parameters prevalent in the alloy. Furthermore it is pointed out that the dislocation separations observed in the $DO_3$-ordered state cannot be explained by the existing models.

Item Type:	Journal Article
Publication:	Materials Science and Engineering A
Publisher:	Elsevier
Additional Information:	Copyright of this article belongs to Elsevier.
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	29 Jun 2006
Last Modified:	19 Sep 2010 04:29
URI:	http://eprints.iisc.ac.in/id/eprint/7736

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