Brownian motion effects on particle pushing and engulfment during solidification in metal-matrix composites

J. B. Ferguson, G. Kaptay, Benjamin F. Schultz, Pradeep K. Rohatgi, Kyu Cho, Chang Soo Kim

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Particle pushing and/or engulfment by the moving solidification front (SF) is important for the uniform distribution of reinforcement particles in metal-matrix composites (MMCs) synthesized from solidification processing, which can lead to a substantial increase in the strength of the composite materials. Previous theoretical models describing the interactions between particle and moving SF predict that large particles will be engulfed by SF while smaller particles including nanoparticles (NPs) will be pushed by it. However, there is evidence from metal-matrix nanocomposites (MMNCs) that NPs can sometimes be engulfed and distributed throughout the material rather than pushed and concentrated in the last regions to solidify. To address this disparity, in this work, an analytical model has been developed to account for Brownian motion effects. Computer simulations employing this model over a range of the SF geometries and time steps demonstrate that NPs are often engulfed rather than pushed. Based on our results, two distinct capture mechanisms were identified: (i) when a high random velocity is imparted to the particle by Brownian motion, large jumps allow the particle to overcome the repulsion of the SF, and (ii) when the net force acting on the particle is insufficient, the particle is not accelerated to a velocity high enough to outrun the advancing SF. This manuscript will quantitatively show the effect of particle size on the steady state or critical velocity of the SF when Brownian motion are taken into consideration. The statistical results incorporating the effects of Brownian motion based on the Al/Al2O3 MMNC system clearly show that ultrafine particles can be captured by the moving SF, which cannot be predicted by any of classical deterministic treatments.

Original languageEnglish
Pages (from-to)4635-4645
Number of pages11
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume45
Issue number10
DOIs
Publication statusPublished - 2014

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metal matrix composites
pushing
Brownian movement
solidification
Solidification
Metals
Composite materials
Nanoparticles
Nanocomposites
nanoparticles
nanocomposites
Particle interactions
critical velocity
Analytical models
matrices
reinforcement
Reinforcement
metals
Particle size
computerized simulation

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Metals and Alloys
  • Mechanics of Materials

Cite this

Brownian motion effects on particle pushing and engulfment during solidification in metal-matrix composites. / Ferguson, J. B.; Kaptay, G.; Schultz, Benjamin F.; Rohatgi, Pradeep K.; Cho, Kyu; Kim, Chang Soo.

In: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, Vol. 45, No. 10, 2014, p. 4635-4645.

Research output: Contribution to journalArticle

Ferguson, J. B. ; Kaptay, G. ; Schultz, Benjamin F. ; Rohatgi, Pradeep K. ; Cho, Kyu ; Kim, Chang Soo. / Brownian motion effects on particle pushing and engulfment during solidification in metal-matrix composites. In: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science. 2014 ; Vol. 45, No. 10. pp. 4635-4645.
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