Faceted Peritecric Growth Mechanism of Superconductive RE-Oxides

超导稀土氧化物的刻面周生长机制

• 批准号: 11650766
• 负责人: MORI Nobuyuki
• 金额: $ 2.5万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650766/
• 关键词: YBa2Cu3O7-X; superconductor; peritectic; nucleation; facet; solidification; simulation; superconducting oxide; 超伝導

To clarify the solidification mechanism of unidirectionally solidified superconductive YBCO oxides, numerical and analytical studies were performed on solidification process of faceted 123 (YBa_2Cu_3O_<7-X>) crystals from liquid + 211 phases. Firstly, to clarify the effects of growth conditions and morphologies on the microstructures of 123 crystals, two-dimensional numerical simulation of faceted peritectic growth of 123 crystal was made by evaluating a series of primitive processes ; the faceted growth of 123 crystal, the melting of 211 particles in the liquid and the solute diffusion in the liquid. Solute distributions in the liquid during the 123 growth were calculated by FDM, and the distributions of residual 211 particles and liquid pools in the faceted 123 crystals were calculated from the experimentally obtained log-normal distributions of 211 particles in the liquid of YBCO.The calculated results well agreed with the experimental ones for various growth modes and conditions. Secondary, the transition of macrostructures from columnar to equiaxed 123 crystals in zone-melted or unidirectionally solidified YBCO was also studied analytically. Critical conditions for columnar-equiaxed transition (relations of growth rate (R) and temperature gradient (G) ) were calculated by equating the undercooling(ΔTc) for the columnar growth of faceted 123 cells and that (ΔTt) for the nucleation and growth of new crystals to a fraction of solid : fs (=10^<-10>, or 0.01). To assess the ΔTt, the CCT-curve was determined from TTT-curve, which was obtained by applying a modified Johnson-Mehl-Avrami equation, evaluating the incubation time (tinc) for nucleation in the effective sample volume. Calculated results agreed well with experimental results also for wide ranges of temperature gradient (G).

为了阐明定向凝固YBa_2Cu_3O_（123）氧化物的凝固机理，对液相+ 211晶面的123（YBa_2Cu_3O_（123））晶体的凝固过程进行了数值和解析研究<7-X>。首先，为了阐明生长条件和形貌对123晶体微观结构的影响，通过对123晶体的小面生长、211颗粒在液相中的熔化和溶质在液相中的扩散等一系列原始过程进行二维数值模拟，研究了123晶体的小面外延生长。用有限差分法计算了123晶体生长过程中液相中的溶质分布，并由实验测得的211粒子在液相中的对数正态分布计算了小面123晶体中剩余211粒子和液池的分布，在不同生长方式和条件下，计算结果与实验结果吻合较好。其次，分析了区熔和定向凝固YBCO中柱状晶向等轴123晶的宏观组织转变。通过将多面123胞柱状生长的过冷度（ΔTc）和新晶体成核和生长的过冷度（Δ Tt）等同于固体分数fs（=10^，或0.01），计算了柱状晶-等轴晶转变的临界条件（生长速率（R）与温度梯度（G）的关系）<-10>。为了评估ΔTt，根据TTT曲线确定CCT曲线，TTT曲线通过应用修改的Johnson-Mehl-Avrami方程获得，评价有效样品体积中成核的孵育时间（tinc）。在较宽的温度梯度（G）范围内，计算结果与实验结果吻合较好。

项目成果

Nobuyuki Mori and Keisaku Ogi: "Simulation of Solidification Structures of Faceted 123 Peritectic Crystals in Superconductive YBCO Oxide"Materials Transactions. V.42・No.2. 220-226 (2001)

Nobuyuki Mori 和 Keisaku Ogi：“超导 YBCO 氧化物中多面 123 包晶晶体的凝固结构模拟”材料交易 V.42·No.2（2001）。

N.Mori,T.Kuroki and K.Ogi: "Study of the formation process of solidification structures of faceted 123 peritectic crystals in superconductive YBCO oxide"Proc.of the 1st Asian Conference on Crystal Growth and Crystal Technology (CGCT-1). (To be printed in

N.Mori、T.Kuroki 和 K.Ogi：“超导 YBCO 氧化物中多面 123 包晶晶体的凝固结构形成过程的研究”第一届亚洲晶体生长与晶体技术会议 (CGCT-1) 的论文集。

Nobuyuki Mori and Keisaku Ogi: "Numerical Study on Effects of Growth Mode and Conditions on Faceted 123 Peritecric Growth of Superconductive Oxides"Proc.of 4th Pacific Rim International Conference on MODELING of CASTING & SOLIDIFICATION PROCESSES 1999 (MC

Nobuyuki Mori 和 Keisaku Ogi：“Numerical Study on Effects of Growth Mode and Conditions on Faceted 123 Peritecric Growth of Superconductive Oxides”Proc.of 第四届环太平洋铸造建模国际会议

Nobuyuki Mori and Keisaku Ogi: "Numerical Study on Effects of Growth Mode and Conditions on Faceted 123 Peritecric Growth of Superconductive Oxides"Proc.of 4th Pacific Rim International Conf.on MODELING of CASTING & SOLIDIFICATION PROCESSES 1999. February

Nobuyuki Mori 和 Keisaku Ogi：“Numerical Study on Effects of Growth Mode and Conditions on Faceted 123 Peritecric Growth of Superconductive Oxides”Proc.of 4th Pacific Rim International Conf.on MODELING of CASTING

黒木高志,森信幸,大城桂作: "帯溶融凝固法により作製したYBCO/Ag複合体中のAg分布"日本金属学会誌. 64巻・10号. 910-918 (2000)

Takashi Kuroki、Nobuyuki Mori、Keisaku Oshiro：“通过带状熔融凝固法制备的 YBCO/Ag 复合材料中的 Ag 分布”，日本金属学会杂志，第 64 卷，第 10 期。910-918（2000 年）。