Ni60Ta40非晶合金在远低于玻璃化转变温度的晶化
首发时间:2014-03-28
摘要:采用X射线、示差扫描热分析、离子薄化、透射和扫描透射电子显微技术研究了Ni60Ta40非晶合金的低温热稳定行为。恒加热速率(40 K/min)示差扫描热分析测得非晶合金玻璃化转变温度为998 K。研究发现:非晶样品在常温下长时间离子轰击处理后,具有较强的抵抗非晶弛豫变形的能力。Ni60Ta40非晶合金在903 K等温退火30 min后,发生纳米晶化,析出富Ta的具有面心立方结构的亚稳相。这是该成分非晶合金晶化行为研究中首次关于该亚稳相的报道。结合这类金属玻璃中的微结构和动力学不均匀性、β弛豫,初步探讨了这种纳米晶化现象背后的定性机制。
关键词: Ni60Ta40非晶 晶化 热稳定性 β弛豫
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Crystallization of Ni60Ta40 metallic glass at temperatures far below calorimetric glass transition
Abstract:The thermal stability of Ni60Ta40 metallic glass at temperatures well below glass transition temperature has been studied by X-ray diffraction, differential scanning calorimetry, Ion milling, transmission and scanning transmission electron microscopy. The glass transition temperature of Ni60Ta40 metallic glass was measured to be 998 K by differential scanning calorimetry at a constant heating rate 40 K/min. Ni60Ta40 metallic glass retained amorphous structure after 2 hours ion-bombarding treatment at room temperature. After 30 min annealed at 903 K, Ta-riched nanocrystals with face-centered cubic structure were founded to precipitated from the amorphous matrix. The presence of this metastable phase has not been reported in previous studies. The nanocrystallization phenomenon was discussed in light of the existence of structural and dynamic heterogeneity in a fragile metallic glass microstructure.
Keywords: Ni60Ta40 metallic glass crystallization thermal stability β-relaxation
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No.4590910965383139****
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