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Crystal Nucleation in Pd-Si Alloys

Published online by Cambridge University Press:  15 February 2011

A.J. Drehman  and
D. Turnbull
A.J. Drehman
Affiliation:
Division of Applied Sciences, Harvard University, Cambridge, MA 02138, USA
D. Turnbull
Affiliation:
Division of Applied Sciences, Harvard University, Cambridge, MA 02138, USA
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Abstract

We report here a study of the crystal phase nucleation in undercooled droplets of Pd-Si alloys with composition near the Pd84.5Si15.5 eutectic composition. Molten droplets are released at the top of a drop tube and solidify (to either a crystalline or glassy state) during descent. This provides a containerless (and nearly gravity free) environment so that nucleation due to container walls or vibrations is eliminated. We found that crystallization, due to homogeneous nucleation, is bypassed in droplets of 1 mm diameter when cooled at 760 K/sec. From this an upper limit of the homogeneous nucleation rate is estimated. Results are compared with our previously published study of nucleation in 0.06mm to 0.33 mm diameter droplets, which indicated that nucleation results from heterogeneous surface nucleation and that the number of these nuclei is dependent on the atmosphere in the drop tube.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 9 , 1981 , 81
Copyright
Copyright © Materials Research Society 1982

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References

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