Gradient porosity and large pore size NiTi shape memory alloys

Zhang, Y.P.; Li, D.S.; Zhang, X.P.

doi:10.1016/j.scriptamat.2007.07.043

Cited by 86 publications

(56 citation statements)

References 11 publications

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“…Porosities from nearly dense up to more than 60% are reported [94], but the pore sizes are usually comparatively small ranging from 4 µm [103] to a not more than 100 µm (see Figure 3b[96]). To increase the pore size, Zhang and Li used temporary space holders [104][105][106]. A mixture of elemental powders (average particle size 61 µm for Nickel and 50 µm for Titanium) and ammonium acid carbonate powders (NH4HCO3, average particle size 250 µm, volume fractions ranging from 10 to 30%) was the starting point.…”

Section: Conventional Sinteringmentioning

confidence: 99%

“…[128] and Bansiddhi and Dunont [100,129]. In this method, which is very similar to the approach described by Zhang, Xiong and Li [104][105][106] for conventional sintering, space-holders are added to elemental powder mixtures [128,130] or to pre-alloyed NiTi powder [100,129].…”

Section: Page 19mentioning

confidence: 99%

“…Wu et al [127] and Zhang et al [104] use NH 4 HCO 3 while Bansiddhi and Dumont use NaF [100] and NaCl [129] as space-holders because of the thermodynamic stability in contact with Nickel and Titanium. These methods have some significant differences.…”

Section: Page 19mentioning

confidence: 99%

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Metals for bone implants. Part 1. Powder metallurgy and implant rendering

et al. 2014

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Section: Conventional Sinteringmentioning

confidence: 99%

Section: Page 19mentioning

confidence: 99%

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Metals for bone implants. Part 1. Powder metallurgy and implant rendering

et al. 2014

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“…Development of techniques for control of porous structure [7] opens new prospects for applications. In order to make the most efficient use of this promising material, correct methods of calculation should be applied.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Functional Properties of Porous Shape Memory Alloy

Volkov

Evard

Iaparova

2015

MATEC Web of Conferences

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Abstract.A model accounting for the microstructure of porous TiNi shape memory alloy samples fabricated by selfpropagating high temperature synthesis has been proposed for simulation of their functional-mechanical properties. Structural elements of a porous sample have been approximated by curved beams. An analysis of shapes and sizes of pores and ligaments permitted to identify characteristic sizes of the beams. A mathematical object consisting of rigidly connected small curve beams has been considered. The stress-strain state of a beam was estimated by the classical methods of strength of materials. The microstructural model was used for calculation of the phase deformation of the shape memory material. Simulation of stress-strain curves and phase deformation of a porous TiNi sample on cooling and heating under a constant stress has shown a good correspondence between the experimental data and the results of modeling.

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“…Powder metallurgy techniques, on the other hand, provide the flexibility of low-temperature processing as well as close composition control, as well as mechanical and physical property modifications via adjustment of the processing parameters and characteristics of the powders used. Accordingly, various powder metallurgy methods, such as self-propagating high-temperature synthesis (SHS), [9][10][11][12][13][14] hot isostatic pressing (HIP), [2][3][4][5]15,16] conventional sintering, [4,[17][18][19][20] spark plasma sintering, [21] space holder technique, [6,7,[22][23][24] and metal injection molding (MIM) [25,26] were employed intensively to fabricate TiNi foams. However, incomplete diffusion when elemental powders were used and contamination during processing even when prealloyed powders were used by these methods led to formation of secondary intermetallics (Ti 2 Ni, TiNi 3 , and Ti 3 Ni 4 ) and oxides (Ti 4 Ni 2 O) or carbonitrides, all of which deteriorate the shape memory and superelasticity characteristics.…”

Section: Introductionmentioning

confidence: 99%

Phase Transformation Behavior of Porous TiNi Alloys Produced by Powder Metallurgy Using Magnesium as a Space Holder

Aydoğmuş

Bor

2011

Metall Mater Trans A

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TARIK AYDOG MUŞ, EL _ IF TARHAN BOR, and ŞAK _ IR BOR Porous TiNi alloys with porosities in the range of 51 to 73 pct were prepared successfully applying a new powder metallurgy fabrication route in which magnesium was used as a space holder, resulting in either single austenite phase or a mixture of austenite and martensite phases dictated by the composition of the starting powders, but entirely free from secondary brittle intermetallics, oxides, nitrides, and carbonitrides. Since transformation temperatures are very sensitive to composition, deformation, and oxidation, for the first time, transformation temperatures of porous TiNi alloys were investigated using chemically homogeneous specimens in as-sintered and aged conditions eliminating secondary phase, contamination, and deformation effects. It was found that the porosity content of the foams has no influence on the phase transformation temperatures both in as-sintered and aged conditions, while deformation, oxidation, and aging treatment are severely influential.

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Gradient porosity and large pore size NiTi shape memory alloys

Cited by 86 publications

References 11 publications

Metals for bone implants. Part 1. Powder metallurgy and implant rendering

Metals for bone implants. Part 1. Powder metallurgy and implant rendering

Modeling of Functional Properties of Porous Shape Memory Alloy

Phase Transformation Behavior of Porous TiNi Alloys Produced by Powder Metallurgy Using Magnesium as a Space Holder

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