利用報告書 / User's Reports | ARIM Japan公式ホームページ

【公開日：2025.06.10】【最終更新日：2025.05.12】

課題データ / Project Data

課題番号 / Project Issue Number

24TU0066

利用課題名 / Title

Crystallization of Ti-based metallic glasses

利用した実施機関 / Support Institute

東北大学 / Tohoku Univ.

機関外・機関内の利用 / External or Internal Use

外部利用/External Use

技術領域 / Technology Area

【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-

【重要技術領域 / Important Technology Area】（主 / Main）次世代ナノスケールマテリアル/Next-generation nanoscale materials（副 / Sub）マルチマテリアル化技術・次世代高分子マテリアル/Multi-material technologies / Next-generation high-molecular materials

キーワード / Keywords

電子顕微鏡/ Electronic microscope

利用者と利用形態 / User and Support Type

利用者名（課題申請者）/ User Name (Project Applicant)

Louzguine Dmitri Valentinovich

所属名 / Affiliation

国立研究開発法人産業技術総合研究所

共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes

ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes

長迫実,今野豊彦

利用形態 / Support Type

（主 / Main）機器利用/Equipment Utilization（副 / Sub）,技術代行/Technology Substitution

利用した主な設備 / Equipment Used in This Project

TU-517：透過電子顕微鏡
 TU-520：透過電子顕微鏡

報告書データ / Report

概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)

In-situ transmission electron microscope (TEM) heating of the Ti₅₀Ni₂₂Cu₂₂Fe₆ metallic glass near its glass-transition temperature revealed polymorphic crystallization into spherical cP2 crystals growing linearly over time, with a growth rate at 703 K (2ｘ10^‒10 m/s) far exceeding that predicted by thermal diffusion. This suggests that enhanced atomic mobility at the glass/crystal interface may be driven by differences in thermodynamic potentials. In the Ti₅₀Ni₂₀Cu₂₀Sn₁₀ alloy, crystallization begins with Ti₆Sn₅ phase formation, followed by cP2TiNi and Ni₂SnTi phases, as confirmed by TEM and DSC, indicating a nucleation-and-growth mechanism involving two overlapping transformation steps.

実験 / Experimental

The Ti₅₀Ni₂₂Cu₂₂Fe₆ and Ti₅₀Ni₂₀Cu₂₀Sn₁₀ (at. %) alloy ingots were prepared by arc-melting mixtures of pure (99.9 mass. %) metals in an argon atmosphere. 20 µm thick ribbon samples were prepared by the melt-spinning technique. The structure of the samples was examined by X-ray diffractometry (XRD) with Cu Kα radiation and the JEOL JEM 2000 EX TEM. The foils were prepared by Ar ion-beam polishing.

結果と考察 / Results and Discussion

A polymorphic crystallization reaction forming spherical cP2 crystals in the Ti₅₀Ni₂₂Cu₂₂Fe₆ metallic glass close to its glass-transition temperature was studied by in-situ heating in TEM (Fig. 1). The particles grew linearly in size with time. The crystal growth rate at 703 K obtained by in-situ transmission electron microscopy 2ｘ10^‒10 m/s is orders of magnitude larger than that allowed by thermal long-range diffusion estimated from viscosity. Such an accelerated atomic diffusion at the glass/crystal interface may be influenced by the crystal/glass difference in the thermodynamic potentials. Sn is known to be a biocompatible element that increases the supercooled liquid region in Ti-based metallic glasses. A glassy structure is formed in the Ti₅₀Ni₂₀Cu₂₀Sn₁₀ alloy on melt spinning. The Ti₅₀Ni₂₀Cu₂₀Sn₁₀ metallic glass did show glass transition on heating and a nucleation-and-growth type phase transformation on heating starting at 497 ^oC above the glass-transition temperature of 460 ^oC. Isothermal calorimetry performed using the same DSC machine showed that the initial crystallization peak in turn consists of two closely overlapping peaks (P1 and P2) one immediately following the other. The sample annealed to the beginning of crystallization (P1) showed the primary formation of the hexagonal Ti₆Sn₅ phase. Transmission electron microscopy indicated that after the annealing in-situ in DSC for 100s at 475 ^oC the spherical particles ranging from 3 to 25 nm in size were formed (Fig. 2). After that cP2 TiNi and cubic Ni₂SnTi (a= 6.089 Å) phases were formed.

図・表・数式 / Figures, Tables and Equations

Fig. 1. Bright-field TEM images of the Ti₅₀Ni₂₂Cu₂₂Fe₆ sample in the initial glassy state (a) and upon in-situ annealing at 703 K (b) in the column of JEM 2000 EX microscope. The insets are the corresponding SAED patterns; the pattern in (b) is indexed according to the cP2 phase with a lattice parameter of 304 pm.

Fig. 2. TEM image and SAED pattern of the Ti₅₀Ni₂₀Cu₂₀Sn₁₀ metallic glass after the annealing in-situ in DSC for 100s at 475 ^oC.

その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)

成果発表・成果利用 / Publication and Patents

論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)

D.V. Louzguine-Luzgin, On polymorphic crystal growth in a Ti-Ni-Cu-Fe system metallic glass at the glass-transition temperature, Scripta Materialia, 242, 115927(2024).
DOI: https://doi.org/10.1016/j.scriptamat.2023.115927

口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.

特許 / Patents

特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件