Magneto‐Acoustic Mixing Technology: A Novel Method of Processing Metal‐Matrix Nanocomposites

Abstract

With increasing concerns regarding fossil fuel consumption and the implementation of widespread vehicle lightweighting, light metal matrix nanocomposites (MMNC) are seen as an attractive solution in many industrial sectors including transportation and aerospace, which demand materials that simultaneously possess high strength and low weight. [1–4] However, processing of MMNCs to evenly disperse nanoparticles remains one of the great challenges to the advancement of this technology. Herein, we present a novel method for MMNC fabrication: magneto-acoustic mixing technology (MAMT). This technology uses ohmically decoupled static and alternating magnetic fields to produce high-intensity, non-contact sonication suitable for melt processing. [5] In this study, MAMT is used to disperse dysprosium oxide (Dy2O3) nanorods (25 225 nm 2 ) and erbium oxide (Er2O3) nanospheres (50 nm) in magnesium (Mg) in a high energy density acoustic environment. The resulting materials exhibit novel microstructures influenced by both acoustic and magnetic effects, which combine to break up nanoparticle agglomerations and refine microstructures. As this is the first demonstration of this technology, the versatility of MAMT is highlighted, and its far-reaching impact will be discussed. Ceramic nanoparticle reinforcement of light metals has been extensively evaluated and shown to broadly improve mechanical properties such as strength, toughness, creep resistance, and elastic modulus. [6–8] While nanoparticle reinforcement is desirable, reliable incorporation has proven to be the fundamental challenge to MMNC production, as high surface energies drive particles to agglomerate. [6] When agglomerations are present in the fabricated microstructure, they act as crack nucleation sites, degrading material properties. [9] Melt dispersion methods like horn-based sonication, powder metallurgy, and spray forming have previously been used to disperse nanoparticles, but MAMT presents the opportunity to disperse nanoparticles using a non-contact, bulk processing technique. MAMT is distinct from other electromagnetic mixing, vibration or sonication technologies [10,11] because of its processing flexibility , deriving from the ohmically decoupled system. This facilitates independent control over many of the processing variables, enabling the production of alloys that do not suffer from many of the issues associated with more traditional melt processing technologies, such as contamination from melt-transducer interactions, [12] restricted geometries, and limited interaction volumes. [13]