Additive manufacturing of a functionally graded material from Ti-6Al-4V to Invar: Experimental characterization and thermodynamic calculations

Bobbio, Lourdes D.; Otis, Richard; Borgonia, John Paul; Dillon, R. Peter; Shapiro, Andrew A.; Liu, Zhe; Beese, Allison M.

doi:10.1016/j.actamat.2016.12.070

Cited by 334 publications

(97 citation statements)

References 27 publications

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“…• shape complexity: it is possible to take advantage of great geometrical freedom in order to reduce several parts in an assembly and/or using design optimization methodologies (TO), which opens a new world of customization possibilities [8][9][10]; • material complexity: multi-material parts can be built [11][12][13]; non-weldable materials can be joined [14]; coatings can be applied [15,16]; and surface finishing can be performed (polishing) [17]; • hierarchical complexity: multi-scale structures can be designed and fabricated using a geometric mesostructure in order to provide information to the part-scale macrostructure (i.e., lattices with negative or zero or positive coefficients of thermal expansion) [9,18,19];…”

Section: Introductionmentioning

confidence: 99%

“…compute sensitivity ∂ f /∂ξ based on print densities (Equation (17) or Equation (18)); (c) update sensitivities using the sensitivity information of the fabrication model. In a layer-wise loop following the reversed print direction, apply Equations (19) and (20) in order to update them; (d) perform the filtering operation in order to obtain the final sensitivities using Equation (12). (e) calculate new x using an optimizer (f) compute physical densities, ρ, using Equations (7) and (8); (g) Compute print densities, ξ.…”

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confidence: 99%

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Designing Self Supported SLM Structures via Topology Optimization

Barroqueiro

Andrade‐Campos

Valente

2019

JMMP

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The potential of Additive Manufacturing (AM) is high, with a whole new set of manufactured parts with unseen complexity being offered. However, the process has limitations, and for the sake of economic competitiveness, these should also be considered. Therefore, a computational methodology, capable of including the referenced limitations and providing initial solid designs for Selective Laser Melting (SLM) is the subject of the present work. The combination of Topology Optimization (TO) with the simplified fabrication model is the selected methodology. Its formulation, implementation, and integration on the classic TO algorithm is briefly discussed, being capable of addressing the minimum feature size and the overhang constraint limitations. Moreover, the performance and numerical stability of the methodology is evaluated, and numerical variables, such as the accuracy of structural equilibrium equations and the material interpolation model, are considered. A comparative study between these variables is presented. The paper then proposes an enhanced version of the selected methodology, with a better convergence towards a discrete solution.

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Designing Self Supported SLM Structures via Topology Optimization

Barroqueiro

Andrade‐Campos

Valente

2019

JMMP

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“…Functionally graded materials (FGMs) have been developed through different processes to tailor the properties for specific purposes. [17] Hosseini et al [18] recently developed a technique to produce FGM, aiming at facilitating and accelerating microstructural characterization. In this novel technique, a steady-state temperature gradient is produced in a disc by applying a stationary arc on the top side while water cooling on the back side.…”

Section: Introductionmentioning

confidence: 99%

Spinodal Decomposition in Functionally Graded Super Duplex Stainless Steel and Weld Metal

Hosseini

Thuvander

Wessman

et al. 2018

Metall Mater Trans A

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Low-temperature phase separations (T < 500°C), resulting in changes in mechanical and corrosion properties, of super duplex stainless steel (SDSS) base and weld metals were investigated for short heat treatment times (0.5 to 600 minutes). A novel heat treatment technique, where a stationary arc produces a steady state temperature gradient for selected times, was employed to fabricate functionally graded materials. Three different initial material conditions including 2507 SDSS, remelted 2507 SDSS, and 2509 SDSS weld metal were investigated. Selective etching of ferrite significantly decreased in regions heat treated at 435°C to 480°C already after 3 minutes due to rapid phase separations. Atom probe tomography results revealed spinodal decomposition of ferrite and precipitation of Cu particles. Microhardness mapping showed that as-welded microstructure and/or higher Ni content accelerated decomposition. The arc heat treatment technique combined with microhardness mapping and electrolytical etching was found to be a successful approach to evaluate kinetics of low-temperature phase separations in SDSS, particularly at its earlier stages. A time-temperature transformation diagram was proposed showing the kinetics of 475°C-embrittlement in 2507 SDSS.

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“…FGM parts are heterogeneous objects with material composition and microstructure that change gradually with positions within the parts [43,44]. Instead of homogeneous porosity throughout the entire structure, the porosity can be functionally graded and varied to match the porosity of adjacent bones after implantation.…”

Section: Features Of Am Orthopaedic Implantsmentioning

confidence: 99%

“…Functionally graded materials (FGM) parts have also been proposed to address the stiffness mismatch between the host bones and implants [43,44]. FGM parts are heterogeneous objects with material composition and microstructure that change gradually with positions within the parts [43,44].…”

Section: Features Of Am Orthopaedic Implantsmentioning

confidence: 99%

Additive manufactured metallic implants for orthopaedic applications

Wong

Scheinemann

2018

Sci. China Mater.

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Metallic implants are commonly used in various orthopaedic surgeries, like fracture fixation, spinal instrumentation, joint replacement and bone tumour surgery. Patients may need to adapt to the fixed dimensions of the standard implants. It may result in suboptimal fit to the host bones and possible adverse clinical results. The standard traditional implants may not address the reconstructive challenges such as severe bone deformity or bone loss after implant loosening and bone tumour resection. With the advent of digital technologies in medical imaging, computer programming in three-dimensional (3D) modelling and computer-assisted tools in precise placement of implants, patient-specific implants (PSI) have gained more attention in complex orthopaedic reconstruction. Additive manufacturing technology, in contrast to the conventional subtractive manufacturing, is a flexible process that can fabricate anatomically conforming implants that match the patients' anatomy and surgical requirements. Complex internal structures with porous scaffold can also be built to enhance osseointegration for better implant longevity. Although basic studies have suggested that additive manufactured (AM) metal structures are good engineered biomaterials for bone replacement, not much peer-reviewed literature is available on the clinical results of the new types of implants. The article gives an overview of the metallic materials commonly used for fabricating orthopaedic implants, describes the metal-based additive manufacturing technology and the processing chain in metallic implants; discusses the features of AM implants; reports the current status in orthopaedic surgical applications and comments on the challenges of AM implants in orthopaedic practice.

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Additive manufacturing of a functionally graded material from Ti-6Al-4V to Invar: Experimental characterization and thermodynamic calculations

Cited by 334 publications

References 27 publications

Designing Self Supported SLM Structures via Topology Optimization

Designing Self Supported SLM Structures via Topology Optimization

Spinodal Decomposition in Functionally Graded Super Duplex Stainless Steel and Weld Metal

Additive manufactured metallic implants for orthopaedic applications

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