Investigation of effect of stress on formation of omega-phase crystals in beta-Ti alloys using in-situ HREM method

使用原位 HREM 方法研究应力对 β-Ti 合金中 omega 相晶体形成的影响

• 批准号: 08650825
• 负责人: SUKEDAI Eiichi
• 金额: $ 1.09万
• 依托单位: Okayama University of Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650825/
• 关键词: beta-Ti allovs.; omega-phase transformation.; HREM.; In-situ observation.; aging under stress.; hvdrostatic pressure.; critical pressure.; initial structure of omega-phase crystals; ω相変態; 静水圧負荷; 高分解電子顕微鏡; 原子半径差; 格子歪

In beta-Ti alloys, omega-phase transformations are occurred due to three ways, that is, quenching from temperature above beta-transus, aging and stressing. omega-phase crystals make beta-Ti alloys harder and more brittle. Recently, it was found that omega-phase crystals become nucleation sites of alpha-transformation by means of longer-time aging or higher temperature aging. beta-Ti alloys including fine alpha-phase particles, (beta+alpha) duplex Ti alloys are stronger and more ductile. The purpose of this research is to develop new methods to make higher density of omega-phase crystals in beta-Ti alloys as nucleation-siters of alpha-phase particles and to clarify the omega-phase transformation mechanism. A high resolution erectron microscope method was used to clarify the beta to omega transformation behaviors at atomic level. The results obtained are as follows :(1). As-quenched omega-phase crystals were unstable, and almost of them disappeared during the heating.(2). Aged omega-phase crystals grew from the remained as-quenched omega-phase crystals as nucleation sites.(3). A tensile stress during the aging and hydrostatic pressurizing were effective to promote high density aged omega-phase crystals.(4). It was recognized that the critical hydrostatic pressure to make omega-phase crystals was between 0.5 and 0.7 GPa.

在β-Ti合金中，ω相变的发生有三种途径，即从β相变温度以上淬火、时效和应力作用。ω相晶体使β-Ti合金更硬更脆。最近，人们发现，通过较长时间的时效或较高温度的时效，ω相晶体成为α相变的形核位点。β-Ti合金包括细小的α-相颗粒，（β + α）双相Ti合金更坚固且更具延展性。本研究的目的是开发新的方法，使β-Ti合金中的ω相晶体作为α相粒子的形核点，并阐明ω相转变机制。采用高分辨正电子显微镜方法，在原子水平上研究了β → ω相变行为。所得结果如下：（1）.淬火态的ω相晶体不稳定，在加热过程中几乎消失。（二）、老化的ω相晶体从作为形核位点的剩余的淬火ω相晶体生长。（三）、时效过程中的拉伸应力和静水压对促进高密度的ω相晶体时效是有效的。（四）、人们认识到，制造ω相晶体的临界流体静压力在0.5和0.7 GPa之间。

项目成果

H.Mizuta, E. Sukedai: "Investigation about aging behaviours of as-quenched ω-phase crystals in β-type Ti-Mo alloy using in-situ dark field and high resolution electron microscopy" Proc. Sixth Asia-Pacific Conf. on Electron Microscopy. 183-184 (1996)

H.Mizuta，E. Sukedai：“使用原位暗场和高分辨率电子显微镜研究 β 型 Ti-Mo 合金中淬火 ω 相晶体的老化行为”，第六届亚太会议。电子显微镜。183-184（1996）

E. Sukedai, Y. Kitano: "Investigation of initial structures of aged ω-phase crystals in β-type Ti-Mo alloys using high resolution electron microscopy" Micron.28. 269-277 (1997)

E. Sukedai、Y. Kitano：“使用高分辨率电子显微镜研究 β 型 Ti-Mo 合金中老化 ω 相晶体的初始结构”Micron.269-277 (1997)。

E. Sukedai, H. Nishizawa: "Investigation of the effects of stresses on the formation of ω-phase crystals in β-type Ti-Mo alloys" Inst. Phys. Conf. Ser. 153,. 569-572 (1997)

E. Sukedai，H. Nishizawa：“β 型 Ti-Mo 合金中 ω 相晶体形成的影响的研究”Inst. Phys Ser 153，。

E.Sukedai, Y.Kitano and A.Ohnishi: "Investigation of initial structures of aged omega-phase crystals in beta-type Ti-Mo alloys using high resolution electron microscopy" Micron. Vol.28, No.4. 269-277 (1997)

E.Sukedai、Y.Kitano 和 A.Ohnishi：“使用高分辨率电子显微镜研究 β 型 Ti-Mo 合金中老化 omega 相晶体的初始结构”Micron。

第8回電顕サマー・スクール実行委員会、: "電子顕微鏡 基礎技術と応用1997〜ナノ世界への道〜" 佐藤武雄、,

第八届电子显微镜暑期学校执行委员会：“电子显微镜基础技术与应用1997-通向纳米世界”佐藤武雄，