Strong, Ductile Magnesium-Zinc Nanocomposites

Abstract

Incorporated SiC nanoparticles are demonstrated to influence the solidification of magnesiumzinc alloys resulting in strong, ductile, and castable materials. By ultrasonically dispersing a small amount (less than 2 vol pct) of SiC nanoparticles, both the strength and ductility exhibit marked enhancement in the final casting. This unusual ductility enhancement is the result of the nanoparticles altering the selection of intermetallic phases. Using transmission electron microscopy (TEM), the MgZn 2 phase was discovered among SiC nanoparticle clusters in hypoeutectic compositions. Differential thermal analysis showed that the MgZn 2 formation resulted in elimination of other intermetallics in the Mg-4Zn nanocomposite and reduced their formation in Mg-6Zn and Mg-8Zn nanocomposites.

Si3N4 Nanoparticle Addition to Concentrated Magnesium Alloy AZ81: Enhanced Tensile Ductility and Compressive Strength

“…Regarding factor (b), dissolved Al possibly segregated at the liquidSi 3 N 4 nanoparticle interface enabling Mg-Al second phase manipulation at the nanoscale. This is similar to possible dissolved Zn segregation at the liquid-SiC nanoparticle interface enabling nanoscale MgZn 2 precipitation as recently reported [13]. The Si 3 N 4 nanoparticle was originally amorphous in the as-supplied form but adopted a crystalline structure in the nanocomposite as shown in Figures 1(d) and 1(c) (resp.)…”

“…In another case, the superplasticity of Mg-Zn-Zr composite systems containing SiC microparticles or submicroparticles has been studied and attributed to (a) fine grain size (lesser twinning effects) and (b) crystallographic textural effects [7,8]. Concerning solidification processed magnesium alloy nanocomposites, existing representative research literature indicates that (a) good nanoparticle distribution can be achieved in the magnesium matrix and (b) better mechanical properties (specifically ductility) can be achieved due to the addition of nanoparticles [9][10][11][12][13].…”

The Overall Effects of AlN Nanoparticle Addition to Hybrid Magnesium Alloy AZ91/ZK60A

“…Dissolved Zn possibly segregated at the liquid-AlN nanoparticle interface enabling Mg-Zn intermetallic phase manipulation at the nanoscale. This is similar to possible dissolved Zn segregation at the liquid-SiC nanoparticle interface enabling nanoscale MgZn 2 precipitation as recently reported [26]. With a reasonably uniform AlN distribution throughout the AZ91/ZK60A matrix, the nanoparticle-matrix interface area was ample for effectively regulated segregation of 4.80-6.20 wt.% Zn (or 1.21-1.59 vol.…”

Thixoforming of A356/SiC and A356/TiB2 Nanocomposites Fabricated by a Combination of Green Compact Nanoparticle Incorporation and Ultrasonic Treatment of the Melted Compact

“…[1][2][3][4][5] While the ductility of the matrices deteriorates with the addition of micron-sized ceramic particles due to their tendency to crack during mechanical loading and relatively high reinforcement concentration in the matrix, [6] it could be maintained or even improved with a low addition of nanoparticles, e.g., 0.5 or 1.0 wt pct. [5,7] These enhancements in the mechanical properties by nanoparticles are associated with the obstruction of dislocation movement and also the promotion of fine grain sizes. [8][9][10] Also, it is crucial to achieve a uniform distribution of nanoparticles through the matrix and good bonding between the matrix and nanoparticles in order to maximize composite mechanical properties.…”

“…[11][12][13] Although there are a number of available fabrication routes for MMNCs, an ultrasonic method, [5,14] which combines casting with ultrasonic cavitation-based dispersion of nanoparticles in molten alloys, seems an economical and promising route in terms of producing engineering components with complex shapes. [7,15] In the fabrication of MMNCs by liquid state routes, poor wettability (which can affect the bonding at the reinforcement-matrix interface) and the tendency of ceramic nanoparticles to agglomerate and cluster due to their large surface-to-volume ratio are the main barriers to obtaining a uniform dispersion of nanoparticles into the matrix. [5] However, it has been shown that good dispersion of ceramic nanoparticles in molten metals is possible with the ultrasonic method due to high intensity ultrasonic waves with localized implosive impact, namely transient cavitation, and acoustic streaming.…”