Date of Award

Fall 1987

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Advisor

Fournelle, R. A.

Second Advisor

Blumenthal, Robert N.

Abstract

The kinetics of discontinuous precipitation and discontinuous dissolution in a Ni - 2.1 at.% In alloy were investigated in the temperature range of 796 K to 998 K using light and electron microscopy. The velocities and interlamellar spacings were experimentally determined and analysed on the basis of several theories. Petermann and Hornbogen's theory was found to be suitable for analysing the kinetics of both discontinuous precipitation and dissolution. Discontinuous precipitaton [sic] was also analysed using theories proposed by Turnbull, Aaronson and Liu, Calm, Shapiro and Kirkadly, Sundquist and Hillert. It was observed that the Dbh values for precipitation extrapolate well into those obtained for dissolution. The diffusivities obtained for discontinuous precipitation and dissolution are in good agreement with the diffusivities of indium in a stationary nickel grain boundary. This shows that both reactions are controlled by grain boundary diffusion and that the diffusivities are of the same order of magnitude in stationary and moving grain boundaries. Comparison of the data obtained with that of Abdou et. al in a Ni-2.0 at% alloy also shows good agreement.

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