INTERFACIAL MORPHOLOGIES BETWEEN ALUMINA AND SILVER-COPPER-TITANIUM ALLOY

Citation
Hq. Hao et al., INTERFACIAL MORPHOLOGIES BETWEEN ALUMINA AND SILVER-COPPER-TITANIUM ALLOY, Journal of Materials Science, 32(18), 1997, pp. 5011-5015
Citations number
12
Categorie Soggetti
Material Science
ISSN journal
00222461
Volume
32
Issue
18
Year of publication
1997
Pages
5011 - 5015
Database
ISI
SICI code
0022-2461(1997)32:18<5011:IMBAAS>2.0.ZU;2-R
Abstract
Joints of high-purity Al2O3 were made with a Ag57Cu38Ti5 alloy by vacu um brazing at 800 degrees C and 900 degrees C for 30 min. The microstr uctures at the interface between the ceramic and the alloy were examin ed in cross-section by scanning electron microscope (SEM) and on diffe rent planes parallel to the interface layer-by-layer by optical micros cope (OM), respectively. The chemical composition of the reaction prod uct was also analysed by energy dispersive X-ray (EDX). A thin reactio n layer about 1.0 mu m thick was formed on the Al2O3 surface at a temp erature of 800 degrees C. This layer had th ree kinds of morphologies and they were identified as Ag, Cu2Ti4O and AlTi, respectively. Accord ing to SEM and OM results, there were two distinct layers 4.0 mu m thi ck interfacial reaction layer for sample heated at 900 degrees C, one layer in the vicinity of the ceramic consisting mainly of Ti2O and TiO and the other layer near the alloy was CuTi2. A transition layer stru cture composed of Al2O3/Ti2O + TiO/Ti2O + TiO + CuTi2/CuTi2/Ag-Cu was formed at the interface. The Al concentration at the interface was rel atively high and confirmed that the reduction of Al2O3 by Ti occurred, which was consistent with the result of a thermodynamic analysis.