Contribution of low-frequency modes to the specific heat of Cu-Zn-Al shape-memory alloys

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.

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Low-Frequency Damping Measured under Isothermal Conditions: Martensite Variant Interface Motion in Shape Memory Alloys

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.203-205.261 ◽

2002 ◽

Vol 203-205 ◽

pp. 261-264 ◽

Cited By ~ 2

Author(s):

Veronique Pelosin ◽

Andre Rivière

Keyword(s):

Shape Memory Alloys ◽

Shape Memory ◽

Low Frequency ◽

Interface Motion ◽

Martensite Variant ◽

Isothermal Conditions

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Specific heat and entropy change during martensitic transformation in Ni 50 Mn 50−x Ga x ferromagnetic shape memory alloys

Acta Materialia ◽

10.1016/j.actamat.2014.06.036 ◽

2014 ◽

Vol 79 ◽

pp. 159-167 ◽

Cited By ~ 6

Author(s):

Xiao Xu ◽

Takeshi Kanomata ◽

Ryosuke Kainuma

Keyword(s):

Martensitic Transformation ◽

Shape Memory Alloys ◽

Specific Heat ◽

Shape Memory ◽

Entropy Change ◽

Ferromagnetic Shape Memory Alloys ◽

Ferromagnetic Shape Memory

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Low Frequency Damping Properties of Ni-Mn-Ga Shape Memory Alloys

ICOMAT ◽

10.1002/9781118803592.ch83 ◽

2013 ◽

pp. 567-571

Author(s):

S.H. Chang ◽

S.K. Wu ◽

K.N. Lin

Keyword(s):

Shape Memory Alloys ◽

Shape Memory ◽

Low Frequency ◽

Damping Properties

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Sensing Shape Recovery using Conductivity Noise in Thin Films of NiTi Shape Memory Alloys

MRS Proceedings ◽

10.1557/proc-1129-v13-01 ◽

2008 ◽

Vol 1129 ◽

Author(s):

U. Chandni ◽

M.V. Manjula ◽

Arindam Ghosh ◽

H.S. Vijaya ◽

S. Mohan

Keyword(s):

Thin Films ◽

Electrical Resistivity ◽

Shape Memory Alloys ◽

Shape Memory ◽

Shape Recovery ◽

Low Frequency ◽

Static Case ◽

Long Range Correlations ◽

Device Applications ◽

Niti Shape Memory Alloys

AbstractLow frequency fluctuations in the electrical resistivity, or noise, have been used as a sensitive tool to probe into the temperature driven martensite transition in dc magnetron sputtered thin films of nickel titanium shape-memory alloys. Even in the equilibrium or static case, the noise magnitude was more than nine orders of magnitude larger than conventional metallic thin films and had a characteristic dependence on temperature. We observe that the noise while the temperature is being ramped is far larger as compared to the equilibrium noise indicating the sensitivity of electrical resistivity to the nucleation and propagation of domains during the shape recovery. Further, the higher order statistics suggests the existence of long range correlations during the transition. This new characterization is based on the kinetics of disorder in the system and separate from existing techniques and can be integrated to many device applications of shape memory alloys for in-situ shape recovery sensing.

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