Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Microstructure of Reaction Phases and Interfacial Strength in Diffusion Bonding of Pure Ti to Pure Fe
Shigeharu HINOTANI
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JOURNAL FREE ACCESS

1989 Volume 75 Issue 9 Pages 1695-1702

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Abstract

The microstructure and the interfacial strength have been studied for the diffusion bonding pairs between a commercially pure Ti and Fe-0.003 wt%C or Fe-0.015 wt%C.
The transformation of α-Ti into β-phase and the formation of intermetallic compounds (TiFe and TiFe2) were induced by the interdiffusion in Ti/Fe-0.003 wt%C bonding pairs. During the cooling to room temperature, β-phase layer with higher Fe content retained in /β-phase, whereas β-phase layer with lower Fe content transformed into α'-Ti martensite. The specific crystallographic orientation relationship ; (0001)TiFe2//(101)α-Fe [1120]TiFeTiFe2//[111]α -Fe (Burger's relationship) was obtained between TiFe2 and α-Fe.The result indicates that TiFe2 was formed in α-Fe by the diffusion of Ti-atoms.
In Ti/Fe-0.015 wt%C bonding pairs, /β-transformed layer and intermetallic compound layer were not observed at the bonding temperatures below 1 073 K. In this case, TiC precipitates formed along the interface and they hindered the interdiffusion of Ti- and Fe-atoms. However β-transformed layer and intermetallic compound layer formed at the bonding temperature above 1 123 K.
The interfacial strength of Ti/Fe-0.003 wt%C bonding pairs depended on the width of intermetallic compound layer ( WIM). At the initial stage of bonding the strength was very low due to the inadequate diffusion, but it increased to the level of 300 MN m-2 in the WIM range between 0.4 and 1.2 μm. The strength decreased rapidly again after the growth of intermetallic compound layer thicker than 1.2 μm.

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© The Iron and Steel Institute of Japan
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