Nucleation and growth of α phase in a metastable β-Titanium Ti-5Al-5Mo-5V-3Cr alloy: Influence from the nano-scale, ordered-orthorhombic O phase and α compositional evolution

SCRIPTA MATERIALIA

卷:194

Article

Antonov, Stoichko¹  Shi, Rongpei²  Li, Dian³  Kloenne, Zachary⁴  Zheng, Yufeng³  Fraser, Hamish L.⁴  Raabe, Dierk¹  Gault, Baptiste^1,5 

[1] Max Planck Inst Eisenforsch GmbH, Dept Microstruct Phys & Alloy Design, D-40237 Dusseldorf, Germany

[2] Lawrence Livermore Natl Lab, Mat Sci Div, Phys & Life Sci Directorate, Livermore, CA 94550 USA

[3] Univ Nevada, Dept Chem & Mat Engn, Reno, NV 89557 USA

[4] Ohio State Univ, Dept Mat Sci & Engn, Ctr Accelerated Maturat Mat, Columbus, OH 43212 USA

[5] Imperial Coll, Dept Mat, London SW7 2AZ, England

关键词: beta-Ti;    alpha precipitation;    Nucleation and growth;    Diffusional-displacive transformation;    Phase transformations;   

DOI  :  10.1016/j.scriptamat.2020.113672

来源: Elsevier

【 摘 要 】

We investigated the nucleation and growth of alpha precipitates in the presence of nano-scale, titanium-rich, ordered-orthorhombic O '' precipitates formed during heating at 5 degrees C/min to 400 degrees C in a metastable beta-Ti alloy, Ti-5Al-5Mo-5V-3Cr. The O '' precipitates are found to assist alpha nucleation by serving as preferential nucleation sites. In the very initial stages of its precipitation, the alpha phase is found to have formed via a coupled diffusional-displacive mode as titanium-rich plates. At this stage, aluminum partitions equally between the beta matrix and the growing alpha precipitates, but slowly diffuses up-hill into the alpha phase during isothermal aging at 400 degrees C for 15 h. The interplay between such pre-formed metastable phases and alpha can be exploited to tailor the microstructure, by refining the alpha distribution, and consequently improve the mechanical properties of beta-Ti alloys. Our work paves the way for exploiting this cascade of metastable phases for further microstructural engineering of beta-Ti alloys. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

【 授权许可】

Free