日本金属学会誌

J. Japan Inst. Metals, Vol. 70, No. 6 (2006),
pp. 473-477

Influence of Shot Peening Condition on Surface Amorphization/Nanocrystallization in TiNi Shape Memory Alloy

Qifeng Cao1,, Koichi Tsuchiya1, Yasunori Harada2, Dacian Tomus1,, Koichi Morii3, Yoshikazu Todaka1 and Minoru Umemoto1

1Department of Production Systems Engineering, Faculty of Engineering, Toyohashi University of Technology, Toyohashi 441-8580
2Department of Materials Science, Graduate School of Engineering, University of Hyogo, Himeji 671-2201
3Research and Development Laboratory, Daido Steels, Co., Ltd., Nagoya 457-8545

Abstract:

Evolution of surface roughness and microstructure in Ti-50.9 mol%Ni shape memory alloy by shot peening were investigated by X-ray diffractometry and transmission electron microscopy. The crystallite size decreased significantly by shot peening of 30 s and remained essentially unchanged after longer peening. TEM observations of the deformed surface layer revealed the formation of amorphous and nanocrystalline in the samples after shot peening for 20 s. In the area with the lower extent of deformation, {114}B2 deformation twins and thin amorphous bands parallel to the twins were found. It implies that the amorphization occurs preferentially along the twin interfaces.


(Received 2005/12/26)

Keywords:

shape memory alloy, shot peeing, amorphization, nanocrystalline materials, severe plastic deformation


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