Microstructural evolution in Ti-10Al-1Zr-1Mo-1Nb alloy under thermomechanical treatment in β-region

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:796

Article

Tanii, Shintaro¹  Umezawa, Osamu^2,3  Yamabe-Mitarai, Yoko^4,5 

[1] Yokohama Natl Univ, Grad Sch Engn Sci, 79-5 Tokiwadai, Yokohama, Kanagawa 2408501, Japan

[2] Yokohama Natl Univ, Fac Engn, 79-5 Tokiwadai, Yokohama, Kanagawa 2408501, Japan

[3] Vysokd Skola Banska Tech Univ Ostrava, Ctr Adv Innovat Technol, 17 Listopadu 15, Ostrava 70833, Czech Republic

[4] Natl Res Inst Mat Sci, 1-2-1 Sengen, Tsukuba, Ibaraki 3050047, Japan

[5] Univ Tokyo, Grad Sch Frontier Sci, 5-1-5 Kashiwanoha, Kashiwa, Chiba 2778568, Japan

关键词: Near alpha-type titanium alloy;    Thermomechanical treatment;    Dynamic recovery;    Dislocation motion;    Deformation mechanism;   

DOI  :  10.1016/j.msea.2020.140149

来源: Elsevier

【 摘 要 】

The influence of temperature and strain rate on microstructural evolution in near alpha-type Ti-10Al-1Zr-1Mo-1Nb alloy was studied under uniaxial compression in the beta single-phase-region. Hot compression tests were conducted for up to 75% reduction at temperatures between 1273 K and 1333 K and strain rates between 0.01 s(-1) and 5s(-1). The steady-state of the flow behavior revealed that dynamic recovery in the p single-phase was dominant in the microstructural evolution process, and few dynamically recrystallized grains were detected, except in the vicinity of the pre-existing beta grain boundaries. Two types of configurations such as lamellar alpha(L), and acicular alpha(AC) microstructures were developed, which were consistent with the compressive deformation mechanism in the beta-region. The alpha(L) microstructure consisted of alpha platelets that were developed via growth of a specific variant, whereas the alpha(AC) microstructure consisted of individual alpha platelets with a different variant in the prior-beta matrix. The stress exponent and activation energy were evaluated to determine the deformation mechanism. The heterogeneous nucleation of individual alpha platelets in the cellular structure (sub-grains) without a specific orientation in the beta matrix resulted in the alpha(AC) microstructure. In contrast, the substructure as uniformly distributed dislocations in prior-beta grains under the viscous motion of dislocations promoted a single variant selection to form alpha(L), platelets in the transformation. When the viscous drag dislocation motion in the beta-region is dominant, a large crystal rotation is detected in the acicular (side plate) alpha(SP) platelets in the vicinity of the prior-beta grain boundary.

【 授权许可】

Free