The influence of coherent ticu plate-like precipitates on the thermoelastic martensitic transformation in melt-spun Ti50Ni25Cu25 shape memory alloys
The influence of coherent ticu plate-like precipitates on the thermoelastic martensitic transformation in melt-spun Ti50Ni25Cu25 shape memory alloys
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DOI：
10.1016/s1359-6454(01)00055-6
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发表时间：
2001-05
期刊：
影响因子：
9.4
通讯作者：
H. Rösner;P. Schlossmacher;A. Shelyakov;A. Glezer
中科院分区：
文献类型：
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作者：
H. Rösner;P. Schlossmacher;A. Shelyakov;A. Glezer
对成分为Ti_（50）Ni_（25）Cu_（25）的非晶快淬薄带在晶化温度以上、附近或以下进行了不同时间的热处理，以获得三种不同的析出物数量状态。详细地说：分别是没有沉淀物以及具有中等和高密度沉淀物的均质化材料。利用差示扫描量热仪（DSC）和透射电镜（TEM）对材料的热弹性转变行为和微观结构进行了表征。等温热处理过程中，在母相B2的{100}面上出现了TiCu共格薄片。特别是，长期退火导致形成的矩形细胞结构作为密集沉淀板的结果。这种组织使相变曲线峰形变宽，相变温度降低。提出了一个热力学描述阐明所观察到的转变行为。讨论了可能的原因，即内应力、晶粒尺寸效应、分解、有序化/无序化。
Amorphous melt-spun ribbons with the composition Ti50Ni25Cu25were heat-treated for various times above, near or below the crystallization temperature in order to achieve three different states concerning the quantity of precipitates. In detail: homogenized material without precipitates as well as with a moderate and a high density of precipitates, respectively. The thermoelastic transformation behavior and the arising microstructures were characterized by means of differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Precipitates appeared in form of thin coherent TiCu plates on {100}-planes of the parent B2-phase during isothermal heat-treatments. Especially, long-term annealing led to formation of rectangular cell structures as a result of densely precipitated plates. As to this microstructure, the peak form of the transformation curves was broadened and the transformation temperatures were lowered. A thermodynamic description is proposed elucidating the observed transformation behavior. The potential reasons, that is, internal stresses, grain size effect, decomposition, ordering/disordering, are discussed.