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Towards an Understanding of the Reaction Sequences in Brazed Joints: Investigation of the Ti-Cu-O Ternary at 945°C.

Published online by Cambridge University Press:  15 February 2011

G. P. Kelkar ,
A. H. Carim  and
K. E. Spear
G. P. Kelkar
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802.
A. H. Carim
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802.
K. E. Spear
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802.
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Abstract

The joining of ceramics using active metal braze alloys is an attractive technique and has been used for a variety of material systems. The braze alloys usually contain an active element such as Ti which can reduce the ceramic and form a strong bond across the interface. Microstructural characterizations of brazed interfaces have been widely reported, though reasons for the formation of reaction products and their sequence is not clear due to the lack of thermodynamic information on the phases formed.

The Ag-Cu-Ti/Al2O3 system contains an interface where Ti, the active element in the braze alloy, reduces Al2O3 to form layers of reaction products which include (Ti,Cu,Al)6O, an M6X type compound. In this study we have looked at the Ti-Cu-O system as a first step towards understanding the Ag-Cu-Ti/Al2O3 system. A section of the Ti-Cu-O ternary was investigated at 945°C. The system contains two M6X type compounds, Ti4Cu2O and Ti3Cu3O, which have independent single phase fields. A Ti activity diagram was generated from the available thermodynamic information and the knowledge of the ternary section. The two reaction sequences reported for such interfaces were analyzed based on the activity diagram.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 314: Symposium R – Joining and Adhesion of Advanced Inorganic Materials , 1993 , 71
Copyright
Copyright © Materials Research Society 1993

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