Initial stage hot pressing of monosized Ti and 90% Ti-10% TiC powders

Taylor, Nevin; Dunand, David C.; Mortensen, Alicja

doi:10.1016/0956-7151(93)90030-v

Cited by 33 publications

(24 citation statements)

References 16 publications

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“…First, in powder sintering processes, loose Ti powders are partially sintered or hotpressed into a porous body. [16][17][18] A variation on this approach mixes a temporary space-holder to the Ti powders to create large pores; after the removal of the space-holder, the Ti powders are fully sintered to create the struts of the foam. 19,20) Second, in the pore expansion processes, argon gas is entrapped in a Ti body during hot-compaction of Ti powders; the resulting argon bubbles are then expanded by exposure to high temperature, where the densified Ti matrix creeps rapidly.…”

Section: Introductionmentioning

confidence: 99%

Effects of Pore Morphology and Bone Ingrowth on Mechanical Properties of Microporous Titanium as an Orthopaedic Implant Material

Li¹,

Oppenheimer

Stupp

et al. 2004

Mater. Trans.

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Successful bone formation which leads to functional osseointegration is determined by the local mechanical environment around boneinterfacing implants. In this work, a novel porous titanium material is developed and tested and then impact of porosity on mechanical properties as a function of bone ingrowth is studied numerically. A superplastic foaming technique is used to produce CP-Ti material with rounded, interconnected pores of 50% porosity; the pore size and morphology is particularly suitable for bone ingrowth. In order to understand the structure-property relations for this new material, a numerical simulation is performed to study the effect of the porous microstructure and bone ingrowth on the mechanical properties. Using ABAQUS, we create two-dimensional representative microstructures for fully porous samples, as well as samples with partial and full bone ingrowth. We then use the finite element method to predict the macroscopic mechanical properties of the foam, e.g., overall Young's modulus and yield stress, as well as the local stress and strain pattern of both the titanium foam and bone inclusions. The strain-stress curve, stress concentrations and stress shielding caused by the bone-implant modulus mismatch are examined for different microstructures in both elastic and plastic region. The results are compared with experimental data from the porous titanium samples. Based on the finite element predictions, bone ingrowth is predicted to dramatically reduce stress concentrations around the pores. It is shown that the morphology of the implants will influence both macroscopic properties (such as modulus) and localized behavior (such as stress concentrations). Therefore, these studies provide a methodology for the optimal design of porous titanium as an implant material.

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Section: Introductionmentioning

confidence: 99%

Effects of Pore Morphology and Bone Ingrowth on Mechanical Properties of Microporous Titanium as an Orthopaedic Implant Material

Li¹,

Oppenheimer

Stupp

et al. 2004

Mater. Trans.

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show abstract

“…Two previous studies on CP-Ti powder hot pressing were carried out at temperatures where titanium is in its a-phase [1003 K, 1073 K, and 1143 K (730°C, 800°C, and 870°C)] [10,15] or its b-phase 1253 K (980°C). [10,15] The experimental densification curve measurements were compared with models based on dislocation creep mechanism (Eq.…”

Section: A Densification Of Cp-ti Powdersmentioning

confidence: 99%

“…[3][4][5][6] Powder densification at increased temperature is accelerated by the application of an external stress, [7][8][9][10] through deformation at contact points between powders, which is controlled by the power-law creep mechanism with the constitutive equation…”

Section: Introductionmentioning

confidence: 99%

Finite-Element Modeling of Titanium Powder Densification

Ye¹,

Matsen

Dunand

2011

Metall Mater Trans A

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A powder-level, finite-element model is created to describe densification, as a function of applied stress during uniaxial hot pressing, of CP-Ti and Ti-6Al-4V powders with spherical or spheroidal shapes for various packing geometries. Two cases are considered: (1) isothermal densification (in the a-or b-fields of CP-Ti and in the b-field of Ti-6Al-4V) where power-law creep dominates and (2) thermal cycling densification (across the a/b-phase transformation of Ti-6Al-4V) where transformation mismatch plasticity controls deformation at low stresses. Reasonable agreement is achieved between numerical results and previously published experimental measurements and continuum modeling predictions.

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“…Kinetics of densification of unalloyed titanium can be accelerated by uniaxial pressing, which was investigated below and above the allotropic temperature of titanium (882 C), resulting in porosity between 5 and 35 %. [18,19] Oh et al [20,21] sintered spherical unalloyed titanium powders with and without applied pressure and achieved 5±37 % porosity. Young's modulus and compressive yield strength decreased linearly with increasing porosity, and at 30 % porosity, the stiffness of the porous titanium was close to that of human bone (ca.…”

Section: Sintering Of Uniform Powder Preformsmentioning

confidence: 99%

“…Cross-section of foam produced by partial sintering of CP-Ti powders, showing sharply cusped, open porosity (porosity: 24 %)[18].…”

mentioning

confidence: 99%

Processing of Titanium Foams

Dunand¹

2004

Adv Eng Mater

316

184

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Because of their excellent mechanical properties, low density and biocompatibility, titanium foams are attractive for structural and biomedical applications. This paper reviews current techniques for titanium foam processing, which are all based on powder‐metallurgy because of the extreme reactivity of liquid titanium. A first group of processes is based on powder sintering with or without place‐holder or scaffolds. A second group relies on expansion of pressurized pores created during prior powder densification.

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Initial stage hot pressing of monosized Ti and 90% Ti-10% TiC powders

Cited by 33 publications

References 16 publications

Effects of Pore Morphology and Bone Ingrowth on Mechanical Properties of Microporous Titanium as an Orthopaedic Implant Material

Effects of Pore Morphology and Bone Ingrowth on Mechanical Properties of Microporous Titanium as an Orthopaedic Implant Material

Finite-Element Modeling of Titanium Powder Densification

Processing of Titanium Foams

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