Internal Friction Parameter in Shape Memory Alloys: Correlation Between Thermomechanical Conditions and Damping Properties in NiTi and NiTiCu at Different Temperatures

Author(s):  
Francesca Villa ◽  
Elena Villa ◽  
Adelaide Nespoli ◽  
Francesca Passaretti
2006 ◽  
Vol 319 ◽  
pp. 33-38 ◽  
Author(s):  
I. Yoshida ◽  
Kazuhiro Otsuka

Low frequency internal friction of Ti49Ni51 binary and Ti50Ni40Cu10 ternary shape memory alloys has been measured. The effect of solution and aging heat treatments on the damping property was examined. The temperature spectrum of internal friction for TiNi binary alloy consists, in general, of two peaks; one is a transition peak which is associated with the parent-martensite transformation and is rather unstable in a sense that it strongly depends on the frequency and decreases considerably when held at a constant temperature. The other one is a very high peak of the order of 10-2, which appears at around 200K. It appears both on cooling and on heating with no temperature hysteresis, and is very stable. The behavior of the peak is strongly influenced by the heat treatments. The trial of two-stage aging with a purpose of improving the damping capacity has been proved unsatisfactory. TiNiCu has a very high damping, the highest internal friction reaching 0.2, but by quenching from very high temperature, say 1373K, the damping is remarkably lowered. For the realization of high damping the quenching from a certain temperature range around 1173K seems the most preferable condition.


1996 ◽  
Vol 06 (C8) ◽  
pp. C8-413-C8-416 ◽  
Author(s):  
E. Cesari ◽  
C. Seguí ◽  
J. Pons ◽  
F. Perelló

1994 ◽  
Vol 211-212 ◽  
pp. 212-215 ◽  
Author(s):  
R.B. Pérez-Sáez ◽  
M.L. Nó ◽  
J. San Juan

2020 ◽  
Vol 1010 ◽  
pp. 34-39
Author(s):  
Ying Ci Wee ◽  
Hamidreza Ghandvar ◽  
Tuty Asma Abu Bakar ◽  
Esah Hamzah

Copper-based shape memory alloys (SMAs) gaining attention due to their high damping properties during martensitic transformation and effective in energy dissipation which is applicable to damping application. However, copper-based SMAs such as the ternary Cu-Al-Ni are not easily deformed in the lower temperature martensitic phase which can be attributed to brittleness induced by coarse grain size, high degree of order and elastic anisotropy. Hence, this study aims to improve the properties of Cu-Al-Ni SMAs by addition of fourth alloying element. In this research, Cu-Al-Ni alloys with the addition of the fourth additional element, cobalt were prepared by casting. Microstructure characteristics of Cu-Al-Ni SMAs with and without Co addition were investigated via scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and x-ray diffraction (XRD). Damping capacity was determined by dynamic mechanical analysis (DMA). It was found that the alloy with 0.7wt% of Co addition showed the best improvement on the damping properties.


1993 ◽  
Vol 119-121 ◽  
pp. 323-330
Author(s):  
Vicente Recarte ◽  
J. Herreros ◽  
M.L. Nó ◽  
José San Juan

2011 ◽  
Vol 326 ◽  
pp. 81-87
Author(s):  
M.B. Bhatty ◽  
Zameer Abbas ◽  
Fazal Ahmad Khalid

Ni-Mn-Ga magnetic shape memory alloys are employed for applications in actuators and sensing devices. Ni-Mn-Ga single crystalline alloys exhibit ferromagnetic shape memory effect with large reproducible strains in moderate magnetic fields. The cost for producing single crystals is high and there is a requirement to investigate the polycrystalline Ni-Mn-Ga alloys for similar applications. This work presents a study of the effect of composition and heat treatment on the microstructure, in polycrystalline off-stoichiometric compositions of high Ni, Ni-Mn-Ga alloys. Cast polycrystalline alloys were homogenized and analysed using optical microscopy, X-ray diffraction, and thermal analysis. Stability of the martensitic transformation temperature was studied by aging the alloys at different temperatures. Martensitic structure was found in both the alloys (~ 54at% and 58 at%). The alloy with high Ni~58 at% content was found to be having a dual phase structure (martensite and FCC γ). Single phase Ni-Mn-Ga alloy has shown transformation at temperature >400K while the dual phase alloy with Ni ~58at% has transformed at temperature >700K thus making it suitable for high temperature applications. Martensitic stabilization effect was observed in alloy with Ni ~54 at% after aging treatment while it was absent in alloy with ~58at% Ni.


2009 ◽  
Vol 02 (02) ◽  
pp. 73-78 ◽  
Author(s):  
LLUÍS MAÑOSA ◽  
ANTONI PLANES ◽  
EDUARD VIVES ◽  
ERELL BONNOT ◽  
RICARDO ROMERO

This letter reports on stress–strain experiments on a Cu – Zn – Al single crystal performed using a purpose-built tensile device which enables the load applied to the specimen to be controlled while elongation is continuously monitored. From the measured isothermal tensile curves, the stress-induced entropy changes are obtained at different temperatures. These data quantify the elastocaloric effect associated with the martensitic transition in shape-memory alloys. The large temperature changes estimated for this effect, suggest the possibility of using shape-memory alloys as mechanical refrigerators.


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