INTRODUCTION OF REINFORCING PARTICLES INTO LIQUID ALUMINUM

A method for introducing reinforcing microparticles of boron nitride, BN, into an aluminum melt A0 is described. Reinforcing particles in the composition of tablets pressed in a mixture with aluminum microparticles were introduced into liquid aluminum. The aluminum was in a crucible and was intensively stirred by a traveling and rotating magnetic fi eld. Subsequently, the melt crystallized directionally, after which its structure was studied using an electron microscope FEI Quanta 650FEG with an x-ray microanalysis EDAX Octane Elite attachment and an optical microscope Hirox KH-7700. The specifi c electrical resistance of the obtained composite and its mechanical characteristics were also determined in the experiment. In this work, the electromagnetic and hydrodynamic characteristics of the stirred melt were calculated numerically (ANSYS MAXWELL 3D and ANSYS CFX packages, respectively, were used). Patterns of the velocity fi elds and of the shapes of the free surface during the introduction of particles into the liquid metal are presented. Experiments have shown that aluminum composites fi lled with nanoparticles diff er in physical properties from aluminum composites with microparticles. With an increase in the concentration of BN nanoparticles (100 nm) in aluminum A0 from 0 to 1.3%, its electrical resistance increases by 4%, and the ultimate strength becomes higher by 13%. With an increase in the concentration of BN nanoparticles (3–5 μm) in aluminum A0 from 0 to 1.3%, its electrical resistance increases by 6.8%, and the ultimate strength, respectively, only by 4%. The experiment showed that an increase in the percentage concentration of reinforcing nanoparticles in aluminum leads to a faster increase in the ultimate strength and to a slower increase in the electrical resistivity than with the introduction of reinforcing microparticles.
   
Author:  S. Yu. Khripchenko, V. M. Dolgikh, R. R. Siraev
Keywords:  MHD mixing, aluminum composite, introduction of reinforcing particles, electrical resistance, ultimate strength, numerical experiment
Page:  732