Cu-Content Dependence of Shape Memory Characteristics in Ti&amp;ndash;Ni&amp;ndash;Cu Alloys

Nam, Tae Hyun; Saburi, Toshio; Shimizu, K.

doi:10.2320/matertrans1989.31.959

Cited by 395 publications

(209 citation statements)

References 11 publications

Supporting

Mentioning

182

Contrasting

Unclassified

Order By: Relevance

“…(1) [18], which showed that NiTiCu alloys do not transform from the B19 to B19 0 phase if the Cu content is higher than 20 at.%. The electrical-resistivity change shows the martensitic transformation from B2 to B19 phase at 339 K with very little hysteresis of about 2 K. Positron lifetime t m of the Ni 30 Ti 50 Cu 20 alloy decreases slightly from 128 to 125 ps as temperature is lowered in the temperature range of B2 phase.…”

Section: Resultsmentioning

confidence: 99%

Pre-martensitic phenomena of thermoelastic martensitic transformation of NiTiCu alloys studied with positron annihilation lifetime spectroscopy

Katsuyama¹,

Araki²,

Mizuno³

et al. 2004

Science and Technology of Advanced Materials

View full text Add to dashboard Cite

Many anomalous phenomena have been observed in NiTi alloys above martensite start temperature, such as softening of the shear constants, increase of internal friction and diffuse scattering of TEM. However, little information has been obtained about the change in the electron system of the parent phase prior to the martensitic transformation, which should be the origin of all pre-martensitic phenomena. In this work, the temperature change of positron annihilation lifetime, which is quite sensitive to electronic-structural changes of matter, were carried out for NiTiCu alloys. The alloys show martensitic transformation from a B2 (cubic) phase to a B19 0 (monoclinic) phase via a B19 (orthorhombic) phase as the temperature is lowered. We have found anomalous positron lifetime changes in Ni 10 Ti 50 Cu 40 and Ni 15 Ti 50 Cu 35 alloys which show a B2-B19-B19 0 phase transformation. Positron lifetime increases anomalously with decreasing temperature at temperatures higher than the transformation temperature into a B19 0 phase. On the other hand, positron lifetime does not show any anomaly in the B2 phase of Ni 30 Ti 50 Cu 20 alloy which shows B2-B19 phase transformation. The positron lifetime of the parent B2 phase shows good agreement with the theoretically-calculated value. Those of the martensite phases of B19 and B19 0 , although, are about 30 ps longer than calculated ones. This big difference between experimental and calculated positron lifetimes cannot be explained by any existing theory.

show abstract

Section: Resultsmentioning

confidence: 99%

Pre-martensitic phenomena of thermoelastic martensitic transformation of NiTiCu alloys studied with positron annihilation lifetime spectroscopy

Katsuyama¹,

Araki²,

Mizuno³

et al. 2004

Science and Technology of Advanced Materials

View full text Add to dashboard Cite

show abstract

“…Widespread results have appeared in the literature connected with the cubic B2 to monoclinic B19'-structure (as in NiTi [l], NiTiCus [2] alloys) or with the cubic B2 to orthorhombic B19 transformation (as in Ni40Ti~OC~10 alloys ; in some cases, as in NiTi alloys, where two transformations may be present (the B2+Rphase and the Rphase-+B19' [6]), even overlapping in the same temperature domain, the sign of the resistivity change connected with the electronic structure modification has greatly helped to identifj the sequence of transformations on the temperature scale.…”

Section: Introductionmentioning

confidence: 99%

The Electric Resistance of Shape Memory Alloys in the Pseudoelastic Regime

1997

View full text Add to dashboard Cite

Abstract. The electric resistance, sensitively dependent on the electronic structure and currently used to detect transformation temperatures in shape memory alloys, deserves attention also in the stress transformation domain. In fact, the electric resistance has already been investigated under increasing stress in the martensitic phase of several shape memory alloys: in this case a linear relationship is found between the electric resistance variation and the built-in deformation related to the variant reorientation process, at least in NiTi alloys. In the stress transformation range at constant temperature, the results are less clear, notably inNiTi alloys where two transformations, the Rphase+M and the P+M, are often present. The aim of this paper is to investigate the electric resistance dependence in the pseudoelastic regime in some selected shape memory alloys where one single transformation is present. Attention has been focused here on a NizsTi~oCu~ alloy, obtained by melt-spinning, where just the cubic(B2)~rthorhombic(B19) transformation is present and on a CuAIBe alloy where the cubic(DO~)++orthorhombic(l8R) is expected. Both alloys show good pseudoelastic loops though with different features: the former shows a critical stress to induce the B19 phase constant all along the transformation plateau, whilst the latter shows a linear superelastic behaviour. The electric resistance variation, detected during the stress induced martensitic transformation, shows a nice linear behaviour, reversible with the transformation direction. The results are compared with the ones obtained on NiTi alloys.

show abstract

“…Interest for ternary alloys relays mainly on the following arguments: reduction of transformation temperature sensitiveness to chemical composition; reduction of thermal hysteresis; reduction of mechanical hysteresis and better cycling behavior [1]. The possible use of these alloys as actuator materials is strictly connected to their fatigue life.…”

Section: Introductionmentioning

confidence: 99%

NiTiCu shape memory alloy : Superplastic elongation during thermal cycling

Bassani¹,

Besseghini²

2001

J. Phys. IV France

View full text Add to dashboard Cite

We report on experimental results obtained in the characterization of a Ni 4 5Ti 5 oCu5 shape memory alloy tested in order to verify its properties at the light of the use in actuators. In this field long term stability of the recovery properties and low hysteresis values are the main requests. Tests were performed in an "ad-hoc" developed device with a maximum number of cycles equal to 5000 and an applied load of 180MPa. Various thermal treatments and cold-working conditions were tested on several specimens in order to identify the combinations that can ensure the best functional properties at the light of the use in actuators. Calorimetric measurements were systematically performed on specimen taken at the beginning and at the end of the cycling procedure. Results confirm that low temperatures and short time thermal treatments account for higher stability in the cycling properties. Surprisingly it has been noted that specimens submitted to complete anneal thermal treatment, in spite of a large plastic deformation during thermomechanical cycling, exhibit only small changes in the recovery properties. A NiTiCu full annealed wire cycled up to rupture can account for a stored plastic deformation up to 60% of the initial length, at the same time demonstrating a complete shape memory effect of 5%. A detailed investigation of the material submitted to this treatment was done in order to clarify its behavior.

show abstract

Cu-Content Dependence of Shape Memory Characteristics in Ti–Ni–Cu Alloys

Cited by 395 publications

References 11 publications

Pre-martensitic phenomena of thermoelastic martensitic transformation of NiTiCu alloys studied with positron annihilation lifetime spectroscopy

Pre-martensitic phenomena of thermoelastic martensitic transformation of NiTiCu alloys studied with positron annihilation lifetime spectroscopy

The Electric Resistance of Shape Memory Alloys in the Pseudoelastic Regime

NiTiCu shape memory alloy : Superplastic elongation during thermal cycling

Contact Info

Product

Resources

About