Nucleation kinetics of continuously cooling Fe–17at.%B droplets produced by controlled capillary jet breakup

Bialiauskaya, Volha; Ando, Teiichi

doi:10.1016/j.jmatprotec.2009.10.011

Cited by 9 publications

(13 citation statements)

References 31 publications

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“…The droplet quenching technique is detailed elsewhere. [24] The two other experiments, in the last two rows in Table 2, to produce 300 mm mono-sized droplets in helium gas and argon gas were done to collect in-flight solidified droplets in a canister containing silicone-based vacuum pump oil placed 0.36 m below the orifice. Due to spray chamber height-limitations, lower initial droplet temperature (melt temperature shown in Table 2) of 1793 K was used for these experiments to assure full in-flight solidification of the 300 mm droplets before they impinge in to the oil in the canister.…”

Section: Fragmentation Modelmentioning

confidence: 99%

“…In the present work, a UDS droplet in-flight solidification model, [10,11] a droplet nucleation kinetic model developed and verified in recent studies, [21][22][23][24] a free dendritic growth model [20] and a dendrite fragmentation model [14] were combined into a microstructure predictive model for the solidification of UDS droplets of the biocompatible alloy F75. The predicted solidification behaviors were experimentally verified with F75 droplets produced by the UDS process.…”

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confidence: 99%

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Nucleation Kinetics and Microstructure Evolution of Traveling ASTM F75 Droplets

Roy

Ando

2010

Adv Eng Mater

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ASTM F75 alloy, a cobalt-chromium-molybdenum alloy with high wear resistance, good strength, and excellent biocompatibility, is popularly used to manufacture artificial dental, hip, and knee replacements. [1] A novel method for using the alloy as a bioimplant involves fabricating a porous mating surface for the bone tissues to grow into for enhanced osseointegration (attachment of the bone to the implant). [2][3][4][5] This anchors the implant firmly to the bone, while making the implant's density and strength similar to those of the human bone. The osseointegration surface is fabricated by sintering balls of diameter 300-700 mm to obtain a porous surface. The present work explores the feasibility of producing F75 balls suitable for the bio-implant applications by the uniformdroplet spray (UDS) process, [6][7][8][9] with particular interest in developing a method to predict the solidification microstructure in relation to the process parameters.The UDS process is a droplet-based manufacturing process where mono-sized droplets are generated by the controlled breakup of a laminar jet of molten metal ejected through an orifice while applying a regulated perturbation. Figure 1(a) schematically illustrates the UDS droplet generator. Details of this process can be found elsewhere. [6][7][8][9] Droplets produced by the UDS process have high sphericity and nearly identical sizes (less than AE3% of target size) [7] and thermal history, which allows for precise control of droplet solidification microstructure. The thermal state of the traveling UDS droplets can be simulated using an in-flight solidification model [10,11] under Newtonian cooling conditions justified on the small Biot numbers that normally apply to UDS droplets. The process parameters of the UDS process, being decoupled, [6] allow for a systematic investigation of the solidification behavior of droplets as a function of experimental variables. The experimental variables are primarily represented by the droplet-cooling rate and volume of the droplet, which determine the amount of undercooling and the path of subsequent solidification, and hence the resultant solidification microstructure, of the droplet. In the UDS process, the droplet-cooling rate is controlled through the droplet size and the choice of cooling gas. The droplet volume, which affects not only the cooling rate but also the number of heterogenenous nucleation sites in a droplet, is controlled through the molten jet diameter, the mass flow rate and the frequency of the imposed perturbation, all of which can be varied independently from each other. This ability, unique to the UDS process, permits stringent control of solidification microstructure for virtually all the droplets in a UDS.In rapid solidification processing, high cooling rates are generally used to produce large prior supercoolings, which promote rapid solidification under a larger driving force, particularly during recalescence. In an alloy, the solid-liquid interface under such conditions normally takes a dendritic morphology, with...

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Section: Fragmentation Modelmentioning

confidence: 99%

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confidence: 99%

Nucleation Kinetics and Microstructure Evolution of Traveling ASTM F75 Droplets

Roy

Ando

2010

Adv Eng Mater

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“…The nucleation distances of the droplets were determined by the splat quenching technique where the droplets were impinged on rotating blades positioned below the orifice. This method for determining the nucleation distance was first used by Bialiauskaya and Ando [15] and later adapted by Roy and Ando [16]. Details of the experimental set-up are provided in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Solidification behavior of highly supercooled polycrystalline silicon droplets

Roy

Ando

2012

Materials Science in Semiconductor Processing

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“…The value of f s can be determined by 3D metallography. 12 a UDS droplets quenched in calorimeter to determine apparent droplet enthalpy (amount of droplet to calorimeter heat transfer); b enthalpy of 185 mm Sn-5Pb droplets determined and simulated as function of flight distance 3 Calorimetric determination of nucleation distance 19 Ando Application of monosize alloy droplets Powder Metallurgy 2012 VOL 55 NO 5 The nucleation distance determined by the above methods is then converted to the nucleation temperature T N with equation (2) where df s /dt50.…”

Section: Nucleation Temperaturementioning

confidence: 99%

“…Solidified monosize balls of a Sn base alloy, 10 b AZ91D 11 and c Fe-4 mass-%B alloy12 1 a schematic of UDS process and b snapshot of uniform jet break-up Ando Application of monosize alloy droplets…”

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Production, characterisation and application of monosize alloy droplets

Ando

2012

Powder Metallurgy

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Monosize alloy droplets are produced by controlled capillary jet break-up, a droplet generating process, also used in ink jet printing technology. With Rayleigh instability controlled through the decoupled process parameters of jet diameter, mass flowrate and perturbation frequency, monosize droplets of desired diameter can be generated at high rates with essentially full yield. The uniform size of droplets assures nearly identical solidification paths for all the droplets generated under fixed process conditions. This permits precise prediction of the motion and thermal and solidification behaviours of the droplets through rigorous process and metallurgical modelling, which is applicable to industrial thermal spray processes as well. Uniform droplets can be in-flight solidified or deposited on a substrate to produce various forms of materials with novel rapid solidification microstructures. Areas of industrial applications are discussed.

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Nucleation kinetics of continuously cooling Fe–17at.%B droplets produced by controlled capillary jet breakup

Cited by 9 publications

References 31 publications

Nucleation Kinetics and Microstructure Evolution of Traveling ASTM F75 Droplets

Nucleation Kinetics and Microstructure Evolution of Traveling ASTM F75 Droplets

Solidification behavior of highly supercooled polycrystalline silicon droplets

Production, characterisation and application of monosize alloy droplets

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