Compaction and Sintering Phenomena in Titanium—Nickel Shape Memory Alloys

Igharo, M.; Wood, J. V.

doi:10.1179/pom.1985.28.3.131

Cited by 106 publications

(80 citation statements)

References 11 publications

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“…[20] An important issue is the choice of alternative production methods as they affect the chemical homogeneity, the porosity, and the contaminants added to the melt. It is, therefore, agreed upon that, although the conventional methods like electric arc melting, vacuum induction melting or combustion synthesis [21] are suitable for production of Ni-Ti alloys, powder metallurgy must also be considered as a beneficial way of production of the near-net-shape, fine-grain material that can be applicable to the aerospace, automotive, or biomedical industry. [22] The formation of B2 phase in NiTi is very sensitive to the chemical composition of the alloy.…”

Section: Introductionmentioning

confidence: 99%

“…[23] New powder-metallurgical techniques such as self-propagation hightemperature synthesis, liquid-phase sintering, explosive shock wave compression, and mechanical alloying have more recently been reported for production of NiTi from pure elemental powders of nickel and titanium. [23][24][25][26][27] Each method has its own advantages, disadvantages and need to further development.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Mechanical Alloying and Sintering on Ni–Ti Powders

Sadrnezhaad

Selahi

2004

Materials and Manufacturing Processes

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Commercially pure nickel-titanium powders were mechanically milled in a vertical attritor mill under protective atmosphere for various times from 10 to 24 hr. Products were then compacted and sintered at different temperatures for different times. Amorphization and interatomic phase formation were determined by X-ray diffractometry, scanning electron microscopy and differential scanning calorimetry. Porosity, virtual density, transition temperatures and the amount of Ni 3 Ti first increased and then decreased with the milling time. Presence of oxygen in the milling atmosphere showed partial crystallization of NiTi intermetallic compound accompanied with titanium oxide formation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Mechanical Alloying and Sintering on Ni–Ti Powders

Sadrnezhaad

Selahi

2004

Materials and Manufacturing Processes

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“…Anisotropy of dimensional change occurs in the radial and axial directions during the sintering of soft metal powders 22 . Control over the dimensions of parts during sintering is vital for their successful processing.…”

Section: Processing and Characterization Methodsmentioning

confidence: 99%

“…However, the effect of formation of eutectic liquid on dimensional stability of the samples needed a close attention. The generation of liquid can result in the expansion of the samples altering their initial designed geometry 22 . To avoid such a phenomenon, the heating rate was decreased to 2°C/min above 700°C until 900°C.…”

Section: 1-powder Characterization and Phase Analysismentioning

confidence: 99%

Synthesis of As-sintered 60NiTi Parts with a High Open Porosity Level

et al. 2018

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60NiTi, despite exhibiting attractive chemical and mechanical properties desirable for biomedical applications, has not yet been processed to a porous structure suitable for general bone replacement applications. In this research, elemental Ni and Ti powders were used to process and manufacture 60NiTi parts by employing conventional press-and-sinter method. Blended Ni and Ti powders provided the possibility of liquid formation in the samples during sintering which leaded to an increase in porosity. Different processing parameters such as pressing pressure, sintering temperature, heating rate and sintering holding time were investigated in a systematic way to obtain 60NiTi parts with approximately 30 Vol.% open porosity. Further, the effects of these processing parameters on the microstructure, phase structure and dimensional stability of the as-sintered parts were investigated. Porous parts with satisfactory dimensional stability were obtained in all cases. It was found that applying lower compaction pressure, final sintering temperatures of above 942°C, faster heating rates and shorter sintering time were beneficial in terms of obtaining parts with more open porosities. Samples sintered at a final temperature of 1050°C did not contain any elemental Ni or Ti material and were ready to be solutionized to obtain hard biocompatible 60NiTi parts.

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“…However, special attention has to be given to the amount of impurities (especially oxygen and carbon) that are almost unavoidable during PM and casting processing of NiTi. Several conventional PM methods including selfpropagating high-temperature synthesis (SHS), reactive sintering, hot isostatic pressure (HIP), hot extrusion and field-activated pressure assisted synthesis have been used for the fabrication of NiTi alloys [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Nonconventional production technologies for NiTi shape memory alloys

Neves

Martins

Oliveira

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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Abstract. The development of new production technologies for NiTi Shape Memory Alloys (SMAs) is always challenging. Recently, we introduced two powder metallurgical (PM) processing routes involving mechanical activation of elemental powder mixtures and densification through extrusion or forging. Those processes were named Mechanically Activated Reactive Extrusion Synthesis (MARES) and Mechanically Activated Reactive FOrging Synthesis (MARFOS). Heat treatments were performed in order to adjust the B2-NiTi matrix composition, yielding a microstructure consisting of a homogeneous dispersion of Ni 4 Ti 3 precipitates embedded in nanocrystalline B2-NiTi matrix. In the present study, we demonstrate the viability of those PM processes for producing NiTi SMAs. With insitu X-ray diffraction and differential scanning calorimetry it is shown that B2-NiTi matrix undergo a B2 R two-step phase transformation.

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Compaction and Sintering Phenomena in Titanium—Nickel Shape Memory Alloys

Cited by 106 publications

References 11 publications

Effect of Mechanical Alloying and Sintering on Ni–Ti Powders

Effect of Mechanical Alloying and Sintering on Ni–Ti Powders

Synthesis of As-sintered 60NiTi Parts with a High Open Porosity Level

Nonconventional production technologies for NiTi shape memory alloys

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