Temperature dependent deformation of the B2 austenite phase of a NiTi shape memory alloy

2013 ◽  
Vol 51 ◽  
pp. 103-121 ◽  
Author(s):  
O. Benafan ◽  
R.D. Noebe ◽  
S.A. Padula ◽  
A. Garg ◽  
B. Clausen ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Austenite Phase ◽  
Niti Shape Memory Alloy ◽  
Temperature Dependent

Temperature-dependent behavior of a polycrystalline NiTi shape memory alloy around the transformation regime

2013 ◽  
Vol 68 (8) ◽  
pp. 571-574 ◽  
Author(s):  
O. Benafan ◽  
R.D. Noebe ◽  
S.A. Padula ◽  
D.J. Gaydosh ◽  
B.A. Lerch ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Niti Shape Memory Alloy ◽  
Temperature Dependent ◽  
Dependent Behavior ◽  
Temperature Dependent Behavior

Material and Process Development of Thin Film Shape Memory Alloy for MEMS Actuator

2015 ◽  
Author(s):  
Cory R. Knick ◽  
Christopher J. Morris
Keyword(s):  
Thin Film ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Phase Change ◽  
Shape Memory ◽  
Microelectromechanical Systems ◽  
Austenite Phase ◽  
Niti Shape Memory Alloy ◽  
Scanning Calorimetry ◽  
Release Process

In this work we discuss the design and fabrication of a cantilever that may be actuated by utilizing the martensite to austenite phase transformation of a sputtered thin film of equiatomic NiTi shape memory alloy (SMA). The cantilever devices were fabricated on a silicon wafer using standard micro fabrication techniques, and may therefore be applicable to microelectromechanical systems (MEMS) switch or actuator applications. This paper details the development of a co-sputtering process to yield a SMA film with controllable composition of Ni50Ti50 and transformation temperature around 60° C. Shape memory effects were characterized using Differential Scanning Calorimetry (DSC), for which we demonstrated martensite-austenite phase change at 57° C for 1–3 um films, annealed at 600° C. We used wafer stress versus temperature measurements as additional confirmation for the repeatable measurement of reversible phase transformation peaking at 73° C upon heating. Up to 62 MPa was available for actuation during the thermally induced phase change. After exploring multiple approaches to a frontside wafer release process, we were successful in patterning and fabricating 10 um wide freestanding Ni50Ti50 cantilevers.

Temperature Effect on the Friction Behavior of NiTi Shape Memory Alloy

2007 ◽  
Vol 353-358 ◽  
pp. 780-783
Author(s):  
Lei Gong ◽  
Lin Mao Qian ◽  
Zhong Rong Zhou
Keyword(s):  
Phase Transition ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Friction Force ◽  
Niti Shape Memory Alloy ◽  
Temperature Dependent ◽  
Friction Behavior ◽  
Force Microscopy ◽  
Atomic Force ◽  
Simple Contact

By using an atomic force microscopy, the friction behavior of a NiTi shape memory alloy is investigated under various temperatures in vacuum environment. Under wearless condition at low loads, the adhesion-dominated friction of NiTi is almost temperature independent. However, while scratch mark appears after friction at high loads, the plough-dominated friction force is found to decrease with the increaase in temperature. Based on a simple contact analysis, the temperature dependent friction behavior of NiTi at high loads may be mainly attributed to the thermoelastic phase transition in NiTi. While temperature increases from 26~100°C, the tensile phase transition stress of NiTi increases from 412~964 MPa, which induces ~27% magnitude decrease in the contact area between the diamond tip and NiTi. It further results in the decrease in the plough-dominated friction force on NiTi.

Impact protection behavior of NiTi shape memory alloy wires

2017 ◽  
Vol 700 ◽  
pp. 132-139 ◽  
Author(s):  
Chuanliang Shen ◽  
Zhipeng Wu ◽  
Zhenhai Gao ◽  
Xiaoyu Ma ◽  
Shengtong Qiu ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Niti Shape Memory Alloy ◽  
Impact Protection
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