Characterization of amorphous and nanocrystalline Ti–Ni-based shape memory alloys

Inaekyan, К.; Braïlovski, Vladimir; Прокошкин, С.Д.; Korotitskiy, Andrey; Glezer, A. M.

doi:10.1016/j.jallcom.2008.05.023

Cited by 52 publications

(28 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It has already been reported in the literature that Ni-Ti can be relatively easily processed by various SPD methods (rolling [18,19,21], ECAP [20]) so it becomes partially or even completely amorphous [22]. The novel feature reported in this manuscript is that similar partially amorphous microstructure exists also in commercial superelastic thin Ni-Ti wires and that this microstructure can be manipulated in a very controlled manner by the FTMT-EC treatment so that the wire is shape set and the required FSP of the wire are obtained.…”

Section: Discussionmentioning

confidence: 99%

Microstructure and functional superelasticity property changes in thin NiTi wires heat treated by electric current

Malard

Pilch

Šittner

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

View full text Add to dashboard Cite

High energy synchrotron X-ray diffraction, transmission electron microscopy and mechanical testing were employed to investigate the evolution of microstructure, texture and functional superelastic properties of 0.1 mm thin as drawn Ni-Ti wires subjected to a nonconventional heat treatment by controlled electric current (FTMT-EC method). As drawn Ni-Ti wires were prestrained in tension and exposed to a sequence of short DC power pulses in the millisecond range. The annealing time in the FTMT-EC processing can be very short but the temperature and force could be very high compared to the conventional heat treatment of SMAs. It is shown that the heavily strained, partially amorphous microstructure of the as drawn Ni-Ti wire transforms under the effect of the DC pulse and tensile stress into a wide range of annealed nanosized microstructures depending on the pulse time. The functional superelastic properties and microstructures of the FTMT-EC treated Ni-Ti wire are comparable to those observed in straight annealed wires.

show abstract

Section: Discussionmentioning

confidence: 99%

Microstructure and functional superelasticity property changes in thin NiTi wires heat treated by electric current

Malard

Pilch

Šittner

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

View full text Add to dashboard Cite

show abstract

“…7,18,19) In the beginning of this alloy design, both values in the tensile strength and the temperature in start for martensite transformation (Ms-temperature) of previously reported TiNi compounds, [20][21][22][23][24][25][26][27][28][29][30] were represented in the Md and Bo diagram, in order to predict their values of designed intermetallics, as described in the following section 2.2 and 2.3. In addition to binary compounds, ternary (or more multi-components) compounds, for example, (M 1Àx Y x )Ti are also located on the Md and Bo map, simply taking the compositional average of the Bo and Md parameters.…”

Section: Parameters Used In D-electrons Conceptmentioning

confidence: 99%

“…Fifty reported TiNi compounds of compositional range (Ti- [25$49] [20][21][22][23][24][25][26][27][28][29][30] are plotted in the Md-Bo map, as shown in Fig. 2.…”

Section: Prediction Of Tensile Strengthmentioning

confidence: 99%

Property-Control of TiNi System Intermetallics and Their Characteristics

et al. 2011

View full text Add to dashboard Cite

The martensitic transformation temperature in addition to the tensile strength and oxidation resistance, were able to be estimated in the crystal structure map using both parameters of the bond order and d-orbital energy level of elements, for the design of TiNi shape memory compounds. The ternary TiNi-(Cr, Re, Fe, Cu, Al) intermetallics having the objective constructed phase, tensile strength, Ms-temperatures and oxidation resistance, were obtained successfully, by the adjustment of both parameters. It is found that the effectiveness of the d-electrons concept could be judged, for property-control of ternary TiNi intermetallics, as well as metallic materials.

show abstract

“…The phenomena of the initial increase in heat flow can be explained by a strongly heterogeneous structure of the cold-rolled and annealed samples [1] with different start temperatures and progression rates of two coinciding transformations: a) crystallization of the amorphous phase and b) growth of the existing nanocrystals. Furthermore, it was shown [10] that in severely CR alloys with mixed amorphous-nanocrystalline structure, the dominant processes during annealing at relatively low temperatures are nucleation (i.e., nanocrystallization of amorphous phase) and grain growth, whereas in moderately CR-alloys, these are stress relaxation and recovery followed by polygonization. Which is why, for severely CR alloys (e = 1 and 1.72), after annealing at temperatures below 325°C, exothermic heat flow related to nucleation and grain growth phenomena is observed in the temperature range from 345 to 380°C, whereas after annealing at higher temperatures (and at any temperature, for moderately CR alloys, e=0.3), endothermic heat flow due to reverse martensitic transformation is measured in the temperature range from 80 to 175°C.…”

Section: Experimental Obesrvationsmentioning

confidence: 99%

Microhardness of binary near-equiatomic Ti-Ni alloys after severe cold rolling and post-deformation annealing

Inaekyan

Braïlovski

Прокошкин

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

Self Cite

View full text Add to dashboard Cite

Abstract. Comparative HV-microhardness and TEM studies of Ti-50.0at%Ni and 50.26at%Ni alloys subjected to cold-rolling (e=0.3, 1 and 1.72) and post-deformation annealing at 100-700°C (1 hour) are presented. Based on the TEM-measured grain size data for Ti-50.0at%Ni alloy as a function of an annealing temperature (T PDA ) higher than 250 o C, it was possible to evaluate the grain size (d) of the near-equiatomic Ti-Ni alloys at T PDA <250 o C, using exponential extrapolation distribution of the d-T PDA data. It was shown that below a critical grain size (d c = 10 nm), the smaller the grain size (as a result of the decrease in annealing temperature), the lower the microhardness. This softening phenomena can be described, with good correlation between the approximation and experimental data, by the normal-abnormal Hall-Petch transition caused by the influence of the intercrystalline regions and by the melting temperature grain-size dependence.

show abstract

Characterization of amorphous and nanocrystalline Ti–Ni-based shape memory alloys

Cited by 52 publications

References 21 publications

Microstructure and functional superelasticity property changes in thin NiTi wires heat treated by electric current

Microstructure and functional superelasticity property changes in thin NiTi wires heat treated by electric current

Property-Control of TiNi System Intermetallics and Their Characteristics

Microhardness of binary near-equiatomic Ti-Ni alloys after severe cold rolling and post-deformation annealing

Contact Info

Product

Resources

About