Microstructure evolution, mechanical properties, and fractography of AA7068/ Si3N4 nanocomposite fabricated thorough ultrasonic-assisted stir casting advanced with bottom pouring technique

Ceramic particulate embedded aluminum metal matrix nanocomposites (AMNCs) possess superior mechanical and surface properties and lightweight features. AMNCs are a suitable replacement of traditional material, i.e., steel, to make automotive parts. The current work deals with developing Si3N4 strengthened high strength AA7068 nanocomposites via novel ultrasonic-assisted stir casting method advanced with bottom pouring setup in the proportion of 0.5, 1.0, 1.5, and 2 wt.%. Planetary ball milling was performed on a mixture of AA7068 powder and Si3N4 (in the proportion of 3:1) before incorporation in aluminum alloy melt to avoid rejection of fine particles. Finite element scanning electron microscope (FESEM), Energy dispersive spectroscopy (EDS), X-Ray diffraction (XRD), and Elemental mapping techniques were used in the microstructural investigation. Significant grain refinement was observed with increasing reinforcing content, whereas agglomeration was found at higher weight %. Hardness, Tensile strength, ductility, porosity content, compressive strength, and impact energy were also examined of pure alloy and each composite. Improvement of 72.71%, 50.07%, and 27.41 % was noticed in hardness value, tensile strength, and compressive strength, respectively, at 1.5 weight % compared to base alloy because of various strengthening mechanisms. These properties are decreased at 2wt.% due to severe agglomeration. In contrast, nanocomposite's ductility and impact strength continuously decrease compared to monolithic AA7068. Fracture analysis shows the ductile and mixed failure mode in alloy and nanocomposites.

Polyphenol, Flavonoid Content and Antioxidant Activity of the Garlic (Allium sativum L.) Extract Obtained by Two Different Extraction Processes

Garlic is a globally used spice due to its pungent taste and a fishy deodorant and digestive stimulator. Owing to the widespread use of garlic in both Oriental and Western medicine, further investigations on garlic extracts might carry important implications in the industry. In this study, we conducted extraction of garlic extraction by two conventional methods and an ultrasonic assisted method. The processes were optimized with respect to various quality parameters including polyphenol, flavonoid content, and antioxidant activity. The results showed that extracting garlic under the ultrasonic support will show higher efficiency than the non-ultrasonic extraction. The optimal extraction parameters are: 70% ethanol solvent, 10/1 solvent / material ratio, 40 °C temperature and 40 minutes time. Keywords: Allium Sativum L., Garic, Polyphenol, Flavonoid, Antioxidant