New studies of nucleation mechanisms in aluminium alloys: implications for grain refinement practice

Schumacher, Peter; Greer, A.L.; Worth, J.H.; Evans, P.V.; Kearns, Martin; Fisher, P. A.; Green, A. H.

doi:10.1179/mst.1998.14.5.394

Cited by 217 publications

(47 citation statements)

References 10 publications

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“…The disregistry is less than 2.5% in each case and the match is marginally better between η-Cu6Sn5 and 1-Cu9Al4 than between η-Cu6Sn5 and δ-Cu33Al17. The overall misfit of ~2.5% in each case is comparable to well-known potent nuclei, such as TiN for Fe [36], Zr for αMg [32], and Al3Ti for αAl [37]. This value is also similar to the lattice mismatch associated with nucleation of metastable NiSn4 on impurity FeSn2 in solders [38].…”

Section: Nucleant Potencysupporting

confidence: 64%

Heterogeneous nucleation of Cu6Sn5 in Sn–Cu–Al solders

Xian

Belyakov

Britton

et al. 2015

Journal of Alloys and Compounds

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Cu6Sn5 is a common intermetallic in Pb-free soldering. We explore the influence of dilute aluminium additions on the heterogeneous nucleation and grain refinement of primary Cu6Sn5 in Sn-4Cu-xAl solders. For cooling rates relevant to soldering, it is found that 0.02 and 0.2wt%Al cause significant grain refinement of Cu6Sn5 with 0.2wt%Al increasing the number of Cu6Sn5 grains per unit area by a factor of ~8. Grain refinement is shown to be due to heterogeneous nucleation of Cu6Sn5 on either delta-Cu33Al17 or gamma1-Cu9Al4, coupled with significant constitutional supercooling ahead of growing Cu6Sn5 crystals. Reproducible orientation relationships are measured between the Cu-Al intermetallics and Cu6Sn5, with a planar lattice mismatch of less than 2.5%. The role of potent nuclei and solutal growth restriction are discussed with reference to the grain refinement of structural casting alloys.

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Section: Nucleant Potencysupporting

confidence: 64%

Heterogeneous nucleation of Cu6Sn5 in Sn–Cu–Al solders

Xian

Belyakov

Britton

et al. 2015

Journal of Alloys and Compounds

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“…For isothermal melt solidification with recalescence, some numerical modeling results suggested that the solid volume fraction was around 0.02%-0.08% at nucleation ceasing [10,24], which is rather small. For recalescence-free solidification cases, due to the lack of precise nucleation ceasing mechanism, the early grain size prediction models have to be based on arbitrarily predetermined thickness of SSN, R [7] or 4.6R [10] (for spherical grains) around growing grains of radius R, which might give solid fraction of 12.5% and 0.6%, respectively, at nucleation ceasing. In our recent model based on the solute segregation stifling mechanism, the solid fraction values of a DC-cast 5182 alloy were predicted in the range of 0.28~0.55% varying with local cooling rate [12].…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous nucleation and grain growth of inoculated aluminium alloys: An integrated study by in-situ X-radiography and numerical modelling

Casari

et al. 2017

Acta Materialia

115

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A comprehensive study on the heterogeneous nucleation and grain growth of Al-10wt.%Cu alloys inoculated with Al-5Ti-1B was carried out. To further reveal the solute segregation stifling mechanism, in-situ near-isothermal melt solidification experiments with constant cooling rates and greatly suppressed melt convection were realized by in-situ microfocus X-radiography study. The kinetics of heterogeneous nucleation and grain growth under the isolated influence of cooling rate and addition level of inoculant particles has been quantitatively studied. Moreover, novel image processing and analysis approaches have been proposed, to determine the maximum

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“…It starts from small nuclei which subsequently grow in size as sphere-like grains once their size has exceeded the critical nucleus size [22]. According to previous investigations, the critical nucleus size (diameter) is in the order of a few nanometers [22,38]. Grains grow in size as additional liquid Al atoms are attracted to their interface and eventually transform to the energy favourable FCC phase after passing through the BCC metastable phase.…”

Section: Nucleationmentioning

confidence: 98%

Large-Scale Molecular Dynamics Simulations of Homogeneous Nucleation of Pure Aluminium

Papanikolaou

Salonitis

Jolly

et al. 2019

Metals

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Despite the continuous and remarkable development of experimental techniques for the investigation of microstructures and the growth of nuclei during the solidification of metals, there are still unknown territories around this topic. The solidification in nanoscale can be effectively investigated by means of molecular dynamics (MD) simulations which can provide a deep insight into the mechanisms of the formation of nuclei and the induced crystal structures. In this study, MD simulations were performed to investigate the solidification of pure Aluminium and the effects of the cooling rate on the final properties of the solidified material. A large number of Aluminium atoms were used in order to investigate the grain growth over time and the formation of stacking faults during solidification. The number of face-centred cubic (FCC), hexagonal close-packed (HCP) and body-centred cubic (BCC) was recorded during the evolution of the process to illustrate the nanoscale mechanisms initiating solidification. The current investigation also focuses on the exothermic nature of the solidification process which has been effectively captured by means of MD simulations using 3 dimensional representations of the kinetic energy across the simulation domain.

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New studies of nucleation mechanisms in aluminium alloys: implications for grain refinement practice

Cited by 217 publications

References 10 publications

Heterogeneous nucleation of Cu6Sn5 in Sn–Cu–Al solders

Heterogeneous nucleation of Cu6Sn5 in Sn–Cu–Al solders

Heterogeneous nucleation and grain growth of inoculated aluminium alloys: An integrated study by in-situ X-radiography and numerical modelling

Large-Scale Molecular Dynamics Simulations of Homogeneous Nucleation of Pure Aluminium

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