Precipitation of two kinds of ? laths in massive ? coexisting with ? lamellae in as-cast Ta-containing TiAl-Nb alloys

The relationship between Ym phase (diffusionless transformation) and Y lamellae (diffusion transformation) and the precipitation of Y laths in Ym were experimentally characterized in a Ta-containing as-cast TiAl-Nb alloy. Unlike the irregular and curved boundary of Ym obtained by completely diffusio...

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Bibliographic Details
Published inMaterials letters Vol. 185; p. 480
Main Authors Zhang, Keren, Hu, Rui, Wang, Xuyang, Yang, Jieren
Format Journal Article
LanguageEnglish
Published Amsterdam Elsevier BV 15.12.2016
Subjects
Alloys
Diffusion
Intermetallic compounds
Materials science
Niobium
Phase transitions
Studies
Tantalum base alloys
Titanium aluminides
Titanium base alloys
Titanium compounds
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Summary:The relationship between Ym phase (diffusionless transformation) and Y lamellae (diffusion transformation) and the precipitation of Y laths in Ym were experimentally characterized in a Ta-containing as-cast TiAl-Nb alloy. Unlike the irregular and curved boundary of Ym obtained by completely diffusionless transformation, Ym phase formed in this work presents a particular orientation relationship with Y lamellae which is confirmed to be 120° rotational relationship. It indicates that Y lamellae can grow through the existed Ym phase due to diffusion-controlled growth. Meanwhile, two kinds of Y laths shown true-twin and pseudo-twin relationship with Ym respectively can be found, which can relax the stress in Ym phase. The precipitation mechanisms of these laths are discussed.
ISSN:0167-577X
1873-4979