Metal Nanopowders Production

An AM60 magnesium alloy nanocomposite reinforced with 1 wt % of AlN nanoparticles was prepared using an ultrasound (US) assisted permanent-mould indirect-chill casting process. Ultrasonically generated cavitation and acoustic streaming promoted de-agglomeration of particle clusters and distributed the particles throughout the melt. Significant grain refinement due to nucleation on the AlN nanoparticles was accompanied by an exceptional improvement in properties: yield strength increased by 103%, ultimate tensile strength by 115%, and ductility by 140%.Although good grain refinement was observed, the large nucleation undercooling of 14 K limits further refinement because nucleation is prevented by the formation of a nucleation-free zone around each grain. To assess the industrial applicability and recyclability of the nanocomposite material in various casting processes, tests were performed to determine the effect of remelting on the microstructure. With each remelting, a small percentage of effective AlN nanoparticles was lost, and some grain growth was observed. However, even after the third remelting, excellent strength and ductility was retained. According to strengthening models, enhanced yield strength is mainly attributed to Hall-Petch strengthening caused by the refined grain size. A small additional contribution to strengthening is attributed to Orowan strengthening.

Section: Methodsmentioning

confidence: 99%

Ultrasound Assisted Casting of an AM60 Based Metal Matrix Nanocomposite, Its Properties, and Recyclability

Dieringa

Katsarou

Buzolin

et al. 2017

“…Magnesium powder (MPF-4 (99.9 wt.%, SOMZ, Solikamsk, Russia)) and aluminum nitride nanopowder were used as initial powders in the work. Aluminum nitride was obtained using the method of electric explosion of wires (EWM) [16]. For deagglomeration of nanoparticles, a powder mixture of Mg-5 wt.% AlN was prepared.…”

Section: Powder Mixturementioning

confidence: 99%

Study of Influence of Aluminum Nitride Nanoparticles on the Structure, Phase Composition and Mechanical Properties of AZ91 Alloy

Khrustalyov

Zhukov

Nikitin

et al. 2022

In this work, magnesium-based composites were obtained by shock-wave compaction of a powder mixture of Mg-5 wt.% AlN at a shock-wave pressure of 2 GPa. Their microstructure was investigated and the phase composition was determined, from which it follows that the nanoparticles retain their phase composition and are uniformly distributed in the magnesium matrix. The materials obtained by shock-wave compaction were used as master alloys for the production of magnesium alloys by die casting. The amount of aluminum nitride nanoparticles in the AZ91 magnesium alloy was 0.5 wt.%. Studies of the microstructure of the magnesium alloys showed a decrease in the average grain size of the magnesium matrix from 610 to 420 μm. Studies of mechanical properties have shown that the introduction of aluminum nitride nanoparticles increases the yield strength from 55 to 119 MPa, the tensile strength from 122 to 171 MPa and the plasticity from 4 to 6.5%, respectively. The effect of nanoparticles on the fracture behavior of the magnesium alloy under tension was determined.

“…The nominal composition (wt.%) of the extruded AM60, according to the producer, (Magontec, Bottrop, Germany) is: 6.0 Al; 0.2-0.4 Mn; and the balance Mg. For the preparation of the nanocomposite, 15 kg of the alloy was melted and 150 g of AlN nanoparticles with an average diameter of ≈80 nm was added under stirring; this corresponds to an AlN concentration of 1 wt.%. The nanoparticles were prepared at Tomsk State University in Tomsk, Russia, and their properties and manufacturing process have been previously described [60,62,63]. The mixture of melt and nanoparticles were treated with high-shear dispersion-treatment (HSDT) for 10 min and, for this purpose, a rotor-stator device (Zyomax Ltd., London, UK) was used at 1000 rpm, exposing the melt permanently to a protective gas mixture of Ar + 1% SF 6 .…”

Section: Materials and Sar Model Solutionmentioning

confidence: 99%

Corrosion Behavior of Extruded AM60-AlN Metal Matrix Nanocomposite and AM60 Alloy Exposed to Simulated Acid Rain Environment

Chávez

Véleva

Feliú

et al. 2021

The present work compared the initial stages of corrosion process development on the AM60-AlN metal matrix nanocomposite surface and on AM60, during their exposure for 30 days to simulated acid rain solution (SAR). The AlN nanoparticles were observed as “attached” to those of Mn-rich AlMn intermetallic particles, forming clusters. The introduction of 1.0 wt.% AlN (≈ 80 nm) in the AM60 alloy carried a slight grain refinement and favored the formation of a denser and more protective corrosion layer, suggested by the electrochemical impedance spectroscopy (EIS) values of higher charge transfer resistance (R2) and capacitance, characteristic of the double layer in the presence of corrosion products, and also suggested by Rn (EN) values, compared to those of the AM60 alloy. Thus, the concentration of the released Mg-ions from the composite surface was lower. Due to the increase in time of the SAR solution pH, Al de-alloying may occur, as well as Al(OH)3 formation, as confirmed by XPS analysis. Due to the presence of Cl-ions in SAR solution, localized corrosion was observed, suggested as fractional Gaussian noise of a stationary and persistent process in time, according to the PSD of the corrosion current fluctuations (EN).