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Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678

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Age Hardening of Si-Bearing Near-α Titanium Alloy Ti–6Al–2.75Sn–4Zr–0.4Mo–0.45Si (Ti-1100) with Two Kinds of Initial Phases
Tatsuaki SakamotoHiroaki AkiyamaSeiya TangeHiromichi Takebe
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JOURNAL FREE ACCESS Advance online publication

Article ID: MT-L2023003

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Abstract

In this study, the effect of the initial phases of the Si-bearing near-α titanium alloy Ti–6Al–2.75Sn–4Zr–0.4Mo–0.45Si (Ti-1100) on Vickers microhardness during aging at 600°C from 5 min to 42 days was investigated by transmission electron microscopy. The initial phases included α′ martensite and α phases. The variation in the hardness of the specimen with the initial α′ martensite phase occurred in the following order: the decrease caused by dislocation recovery, the increase caused by silicide precipitation, the decrease caused by silicide coarsening, and the increase caused by α2 precipitation. As for the initial α phase, hardness initially decreased and then increased because of dislocation recovery and silicide/α2 precipitation, respectively. The difference in age-hardening behavior resulted from the difference between the dislocation amounts in the two initial phases. Silicide precipitation was promoted by dislocations, whereas α2 precipitation occurred via homogeneous nucleation irrespective of the dislocations.

Variation of Vickers microhardness during aging of Ti-1100 specimens with the initial phases of α′ martensite and α phases. Fullsize Image
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© 2023 The Japan Institute of Light Metals
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