scholarly journals Microstructural Characterization and Mechanical Behavior of NiTi Shape Memory Alloys Ultrasonic Joints Using Cu Interlayer

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1830 ◽  
Author(s):  
Wei Zhang ◽  
Sansan Ao ◽  
Joao Oliveira ◽  
Zhi Zeng ◽  
Yifei Huang ◽  
...  

NiTi shape memory alloys (SMAs) are a class of functional materials which can be significantly deformed and recover their original shape via a reversible martensitic phase transformation. Developing effective joining techniques can expand the application of SMAs in the medical and engineering fields. In this study, ultrasonic spot welding (USW), a solid-state joining technique, was used to join NiTi sheets using a Cu interlayer in between the two joining sheets. The influence of USW process on the microstructural characteristics and mechanical behavior of the NiTi joints was investigated. Compared with conventional fusion welding techniques, no intermetallic compounds formed in the joints, which is extreme importance for this particular class of alloys. The joining mechanisms involve a combination of shear plastic deformation, mechanical interlocking and formation of micro-welds. A better bonding interface was obtained with higher welding energy levels, which contributed to a higher tensile load. An interfacial fracture mode occurred and the fracture surfaces exhibited both brittle and ductile-like characteristics with the existence of tear ridges and dimples. The fracture initiated at the weak region of the joint border and then propagated through it, leading to tearing of Cu foil at the fracture interface.

2018 ◽  
Vol 27 (10) ◽  
pp. 106501 ◽  
Author(s):  
Min Zhou ◽  
Yu-Shuang Li ◽  
Chen Zhang ◽  
Lai-Feng Li

Vacuum ◽  
2018 ◽  
Vol 156 ◽  
pp. 135-139 ◽  
Author(s):  
Justyna Witkowska ◽  
Jacek Rudnicki ◽  
Witold Piekoszewski ◽  
Gerhard Raugh ◽  
Jerzy Morgiel ◽  
...  

2001 ◽  
Vol 317 (1-2) ◽  
pp. 85-92 ◽  
Author(s):  
Ken Gall ◽  
Huseyin Sehitoglu ◽  
Rob Anderson ◽  
Ibrahim Karaman ◽  
Yuriy I. Chumlyakov ◽  
...  

2007 ◽  
Vol 465 (1-2) ◽  
pp. 44-48 ◽  
Author(s):  
Niraj Nayan ◽  
Govind ◽  
C.N. Saikrishna ◽  
K. Venkata Ramaiah ◽  
S.K. Bhaumik ◽  
...  

2006 ◽  
Vol 8 (4) ◽  
pp. 247-252 ◽  
Author(s):  
J. Mentz ◽  
M. Bram ◽  
H. P. Buchkremer ◽  
D. Stöver

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