Verification of the Displasive-Diffusion-less Mechanism in Bainitic Phase Transformations by a High Resolution Fractography

通过高分辨率断口验证贝氏体相变中的无弥散扩散机​​制

• 批准号: 10650655
• 负责人: SHIMIZU Kenichi
• 金额: $ 2.56万
• 依托单位: Kanazawa Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650655/
• 关键词: Bainite; Phase Transformation; Atomic Diffusion Type; Displasive-Diffusionless Type; Cu-Zn-Al Alloy; High Resolution Fractography; 高分解能フラクトグラフィ; 高分解能フラクトグラフイ

The bainitic transformation is believed to finally proceed by a diffusion mechanism of atoms. However, there has also been proposed another idea where a displasive-diffusionless mechanism is operated in the nucleation stage and early stage of growth of bainitic transformations. The present investigation was carried out to verify which of the two mechanisms, diffusion or displeasures and atomic compositions of the bainitic plate and its matrix confronted along their interphase boundary on tensile-fractured surfaces, that is, by doing fractography with a high resolution scanning electron microscope (SEM) equipped with a field emission electron gun.The materials used for the verification are carbon steels (JIS S25C and S%%C) and Cu-28.3Xn-6.0Al(at .%) alloy, and the results obtained for the latter alloy will be reported below, because those for carbon steels were previously reported. In order to observe certainly a bainite plate and its matrix confronted on tensile-fractured surfaces, the volume ration of bainite plates to the matrix must be appropriate. The ratio was first examined by changing both isothermal holding temperature and time for the bainitic transformation, and 473 K and 28.8 Ks were found to be appropriate. The bainitic specimens subjected to this heat-treatment were tensile-fractured, and the fractured surfaces were observed by the high resolution fractography. Areas, where a bainite plate and its matrix seem to be confronted, were search, and EDX analyses were performed for the confronted bainite plates and matrices. As a result, it was found that atomic compositions of the plate and matrix were the same, and therefore the displasive-diffusionless mechanism is supposed to be really operated. However, more detailed examination is needed, because a little ambiguity is remained for the identification of bainite plates and matrices confronted on fractured surfaces.

据信贝氏体转变最终通过原子的扩散机制进行。然而，还提出了另一种想法，即在贝氏体相变的形核阶段和生长早期阶段运行相变-无扩散机制。本研究是为了验证贝氏体板及其基体沿着相间边界在拉伸断裂表面上面对的是扩散或不满这两种机制以及原子组成中的哪一种，即通过使用配备场致发射电子枪的高分辨率扫描电子显微镜（SEM）进行断口分析。用于验证的材料是碳钢（JIS） S25C 和 S%%C) 和 Cu-28.3Xn-6.0Al(at .%) 合金，后一种合金获得的结果将在下面报告，因为之前报道过碳钢的结果。为了准确地观察贝氏体板及其基体在拉伸断裂面上的情况，贝氏体板与基体的体积比必须合适。首先通过改变贝氏体转变的等温保持温度和时间来检查该比率，发现 473 K 和 28.8 Ks 是合适的。对经过该热处理的贝氏体试样进行拉伸断裂，并通过高分辨率断口观察了断裂面。搜索贝氏体板及其基体看起来相面对的区域，并对相面对的贝氏体板和基体进行EDX分析。结果发现，板和基体的原子组成相同，因此相变-无扩散机制应该真正起作用。然而，需要更详细的检查，因为对于断裂表面上贝氏体板和基体的识别仍然存在一些模糊性。

项目成果

清水 謙一: "変位型原子無拡散相変態に関する研究の流と学界の動き"日本鉄鋼協会誌"ふぇらむ". 3・2. 31-36 (1998)

清水健一：“关于位移型原子无扩散相变的研究动向和学术动向”日本钢铁学会杂志“Ferram”3·2（1998）。

T.Kakeshita, T.Saburi, K.Shimizu: "Kinetics of Martensitic Transformations in Some Ferrous and Non-Ferrous Alloys"Philosophical Magazine B. 80・2. 71-81 (2000)

T.Kakeshita、T.Saburi、K.Shimizu：“某些黑色金属和有色金属合金中马氏体相变的动力学”哲学杂志 B. 80・2 (2000)。

Y.Kishi, Z.Yajima, K.Shimizu & K.Morii: "Fatigue Crack Growth Properties and Scanning Electron Microscopy of Fatigue Surface of Ti-Ni-Co SMA's"Proc. Intern'l. Symp. & Exhib. On Shape Memory Mater. (Mater. Sci. Forum). 327-328. 123-126 (1999)

Y.岸、Z.矢岛、K.清水

T.Kakeshita, T.Saburi and K.Shimzu: "Kinetics of Martensitic Transformations in Some Ferrous and Non-Ferrous Alloys"Phil.Mag.B. Vol.80, No.2. 71-81 (2000)

T.Kakeshita、T.Saburi 和 K.Shimzu：“某些黑色金属和有色合金中马氏体相变的动力学”Phil.Mag.B。

Y.Kishi,Z.Yajima,K.Shimizu & K.Morii: "Effect of Microstructures on Mechanical Fatigue Crack Growth Character.of a Ti-Ni-Co Mem.Al."Intern'l.Conf.on Martensitic Transformations(ICOMAT'98). 654-657 (1999)

岸Y、矢岛Z、清水K