Quantitative three-dimensional analysis of Ni4Ti3 precipitate morphology and distribution in polycrystalline Ni-Ti
Quantitative three-dimensional analysis of Ni4Ti3 precipitate morphology and distribution in polycrystalline Ni-Ti
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DOI：
10.1016/j.actamat.2010.11.044
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发表时间：
2011-02-01
期刊：
影响因子：
9.4
通讯作者：
Schryvers, D.
中科院分区：
文献类型：
--
作者：
Cao, S.;Nishida, M.;Schryvers, D.
用聚焦离子束/扫描电子显微镜切片观察法研究了Ni50.8Ti49.2非均质多晶形状记忆合金中Ni4Ti3相的三维尺寸、形态和分布。测量和/或计算了晶内和晶界附近析出物的平均体积、中心平面直径、厚度、长径比和球形度。通过确定具有相同转动惯量的等效椭球来量化沉淀物的形态，并根据Zingg方案进行分类。根据沉淀物质心的坐标，得到了描述三维分布的对分布函数。根据这一新的数据，认为非均匀组织的存在可能是由于均匀材料的晶内浓度梯度很小所致，由此产生的多阶段马氏体相变源于与析出物的大小和析出物之间可用B2基体的尺度差异有关的应变效应。(C)2010年Acta Materialia Inc.由爱思唯尔有限公司出版。版权所有。
The three-dimensional size, morphology and distribution of Ni4Ti3 precipitates in a Ni50.8Ti49.2 polycrystalline shape memory alloy with a heterogeneous microstructure have been investigated using a focused ion beam/scanning electron microscopy slice-and-view procedure. The mean volume, central plane diameter, thickness, aspect ratio and sphericity of the precipitates in the grain interior as well as near to the grain boundary were measured and/or calculated. The morphology of the precipitates was quantified by determining the equivalent ellipsoids with the same moments of inertia and classified according to the Zingg scheme. Also, the pair distribution functions describing the three-dimensional distributions were obtained from the coordinates of the precipitate mass centres. Based on this new data it is suggested that the existence of the heterogeneous microstructure could be due to a very small concentration gradient in the grains of the homogenized material and that the resulting multistage martensitic transformation originates in strain effects related to the size of the precipitates and scale differences of the available B2 matrix in between the precipitates. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.