Reports from United States Army Research Laboratory Add New Data to Findings in Metallurgy (Brownian Motion Effects on Particle Pushing and Engulfment During Solidification in Metal-Matrix Composites)
By a News Reporter-Staff News Editor at Journal of Technology -- Fresh data on Metallurgy are presented in a new report. According to news reporting out of Aberdeen Proving Ground, Maryland, by VerticalNews editors, research stated, "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."
Our news journalists obtained a quote from the research from United States Army Research Laboratory, "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."
According to the news editors, the research concluded: "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."
For more information on this research see: Brownian Motion Effects on Particle Pushing and Engulfment During Solidification in Metal-Matrix Composites. Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science, 2014;45A(10):4635-4645. Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science can be contacted at: Springer, 233 Spring St, New York, NY 10013, USA.
Our news journalists report that additional information may be obtained by contacting J.B. Ferguson, US Army Res Lab, Weap & Mat Res Directorate, Aberdeen Proving Ground, MD 21005, United States. Additional authors for this research include G. Kaptay, B.F. Schultz, P.K. Rohatgi, K. Cho and C.S. Kim.
Keywords for this news article include: Aberdeen Proving Ground, Maryland, United States, North and Central America, Metallurgy
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