Straightforward Downsizing of Inclusions in NiTi Alloys: A New Generation of SMA Wires with Outstanding Fatigue Life

被引：5

作者：

Coda A. ^{[1
]}

Cadelli A. ^{[1
]}

Zanella M. ^{[1
]}

Fumagalli L. ^{[1
]}

机构：

[1] SAES Getters S.p.A, Lainate, 20020, MI

来源：

Shape Memory and Superelasticity | 2018年 / 4卷 / 01期

关键词：

Extreme value; Fatigue; Inclusions; NiTi shape memory wires;

D O I：

10.1007/s40830-018-0159-y

中图分类号：

学科分类号：

摘要：

One of most debated aspects around Nitinol quality is microcleanliness, nowadays considered as the main factor affecting fatigue life. Recent results demonstrate that fatigue is undoubtedly associated with inclusions which can act as crack initiators. However, type, size, and distribution of such particles have been observed to strongly depend on Ni/Ti ratio as well as melting and thermo-mechanical processes. Therefore, if a general reduction of non-metallic inclusions is expected to generate a beneficial effect in improving lifetime of Nitinol, on the other hand this necessarily involves a hard review of both material melting and processing. In this work, the characterization of the fatigue behavior of SMA wires with diameter below 100 µm is presented. The wires were prepared by a peculiar, non-standard combination of melting and thermo-mechanical processes (Clean Melt technology). Thermo-mechanical cycling was carried out and the fracture surfaces of all failed wires were investigated by scanning electron microscopy. A robust set of data was collected and analyzed by using the statistics of extremes. Results clearly demonstrate that in the new NiTi Clean Melt alloy the maximum inclusion size and area fraction are significantly reduced compared to standard Nitinol. This offers meaningful improvement in fatigue resistance over standard wires. © 2018, ASM International.

引用

页码：41 / 47

页数：6

共 20 条

[1]

Duerig T.W., Melton K.N., Stockel D., Wayman C.M., Engineering aspects of shape memory alloys, (1990)

[2]

Ionaitis R.R., Directly acting pipeline SM devices for nuclear power plants, Mat Sci For, 327-328, pp. 51-54, (2000)

[3]

Zhang X., Nie J., Hou G., Development of anti-loosening nuts using shape memory alloys, Mat Sci For, 327-328, pp. 35-38, (2000)

[4]

Mantovani D., Shape memory alloys: properties and biomedical applications, JOM, 52, 10, pp. 36-44, (2000)

[5]

Adachi Y., Unjoh S., Kondoh M., Development of a shape memory alloy damper for intelligent bridge systems, Mat Sci For, 327-328, pp. 31-34, (2000)

[6]

Adler P.H., Et al., Martensite transformations and fatigue behavior of nitinol, J ASTM Int, 4, pp. 3-16, (2007)

[7]

Pelton A.R., Nitinol fatigue: a review of microstructures and mechanisms, JMEPEG, 20, pp. 613-617, (2011)

[8]

Wong S., Lin Z.C., Tahran A., Boylan J., Pike K., Kramer-Brown P., An investigation of factors impacting nitinol wire fatigue life, J ASTM Int, 6, pp. 99-107, (2009)

[9]

Reinoehl M., Et al., The influence of melt practice on final fatigue properties of superlesatic NiTi wires, SMST-2000 Proceedings International Conference on Shape Memory and Superelastic Technologies, pp. 397-403, (2000)

[10]

Rahim M., Et al., Impurity levels and fatigue lives of pseudoelastic NiTi shape memory alloys, Acta Mater, 61, 10, pp. 3667-3686, (2013)

← 1 2 →