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Microstructure of Rapidly Solidified Al-Si Exhibiting Enhanced Superconducting Properties

Published online by Cambridge University Press:  25 February 2011

M. A. Noack ,
A. J. Drehman  and
A. R. Pelton
M. A. Noack
Affiliation:
Ames Laboratory-USDOE, Iowa State University, Ames, Iowa 50011
A. J. Drehman
Affiliation:
Ames Laboratory-USDOE, Iowa State University, Ames, Iowa 50011
A. R. Pelton
Affiliation:
Ames Laboratory-USDOE, Iowa State University, Ames, Iowa 50011
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Abstract

Tsuei and Johnson previously reported significantly enhanced superconducting transition temperatures for rapidly solidified Al-Si alloys. Here we report a microstructural study of melt spun Al80 Si20 ribbons to determine the mechanism responsible for this enhancement.

Results of this investigation revealed three distinct microstructures from the top surface to the more rapidly cooled bottom surface (which was in contact with the melt-spinning wheel). Near the top, the microstructure is of hypoeutectic morphology even though this is a hypereutectic alloy. The predominant microstructure is cellular. A 1 to 3 Wm thick layer at the bottom of the ribbon was found to be responsible for the largest enhancement. This layer is composed of fine-grained supersaturated fcc Al containing densely distributed dc Si precipitates. Microdiffraction analysis revealed a cube/cube orientation relationship between the precipitates and the matrix. These results provide insight into the possible mechanism for the enhancement.

Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 62: Symposium Q – Materials Problem Solving with the Transmission Electron Microscope , 1985 , 97
Copyright
Copyright © Materials Research Society 1986

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