Go to  Advanced Search

Dissolution kinetics of Widmanstatten Ag₂Al precipitates

Show full item record

Files in this item

Files Size Format Description   View
UBC_1983_A6_7 S23.pdf 5.482Mb Adobe Portable Document Format   View/Open
Title: Dissolution kinetics of Widmanstatten Ag₂Al precipitates
Author: Sagoe-Crentsil, Kwesi Kurentsir
Degree Master of Science - MSc
Program Metallurgical Engineering
Copyright Date: 1983
Abstract: A combination of SEM and electron-probe studies have been conducted on the dissolution of Widmanstatten γ(Ag₂Al) plates in Al-15.3 wt.% Ag between the temperatures 458°C and 494°C. Individual rather than averaged kinetic events have been monitored in all cases. The mechanism of dissolution observed at the plate tip was found to be different from that operative at the broadface. Precipitates shorten linearly at volume diffusion controlled rates according to the Horvay-Cahn , Zener-Hillert and Jones-Trivedi analyses, adapted for the case of dissolution. The kinetics of thinning were observed to be two orders of magnitude slower than volume diffusion controlled rates indicating an interface-controlled reaction. This interfacial inhibition has further been confirmed by the consistent fall of the interface concentration value below equilibrium solubility values as determined from the electron probe measurements. The electron probe measurements give similar diffusion distances at the tip and broadface and would require short circuit diffusion from the tip to the broadface to be in agreement with the kinetic results. A mechanism to explain the overall reaction has been proposed.
URI: http://hdl.handle.net/2429/24025
Series/Report no. UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/]
Scholarly Level: Graduate

This item appears in the following Collection(s)

Show full item record

All items in cIRcle are protected by copyright, with all rights reserved.

UBC Library
1961 East Mall
Vancouver, B.C.
Canada V6T 1Z1
Tel: 604-822-6375
Fax: 604-822-3893