Strength and elastic modulus enhancement in Mg-Li-Al matrix composites reinforced by ex situ TiB2 particles via stir casting

A novel Mg^(-1)0Li-3Al(wt.%,LA103)matrix composite reinforced by ex situ micron TiB_(2) particles was developed in the present study.The ball milling and cold pressing pretreatment of the reinforcements made it feasible to prepare this material under stir casting conditions with good dispersion.The microstructure and mechanical properties of the composites prepared by different pretreatment methods were analyzed in detail.The TiB_(2) particles in the Al-TiB_(2)/LA103 composite using the pretreatment process were uniformly distributed in the microstructure due to the formation of highly wettable core-shell units in the melt.Compared with the matrix alloys,the Al-TiB_(2)/LA103 composite exhibited effective strength and elastic modulus improvements while maintaining acceptable elongation.The strengthening effect in the composites was mainly attributed to the strong grain refining effect of TiB2.This work shows a balance of high specific modulus(36.1 GPa·cm^(3)·g^(-1))and elongation(8.4%)with the conventional stir casting path,which is of considerable application value.

Controllable synthesis of metallic Bi from commercial Bi_2O_3 via one-pot solvothermal reduction method

Metallic bismuth crystal is one important and interesting semimetal that has attracted great attention owing to its unique thermal and electrical properties. Herein, we report a facile, green, cost-effective and sustainable solvothermal process using ethanol, glycol, isopropanol, phenylcarbinol as solvent and commercial Bi_2O_3 as the starting material to produce high-purity metallic Bi with tunable morphologies on large scale. It is found that all alcohols are capable of reducing Bi_2O_3 to Bi and the reducibility of glycol is proved to be the strongest. The highest purity of the resultant Bi is calculated to be 99.74%. What's more, the morphology of final Bi particles is controllable by adding various types and concentrations of additives. As a consequence, our work lays the root for the large scale solvothermal production of high-purity Bi particles with various regular morphologies.

Porous SiC/melamine-derived carbon foam frameworks with excellent electromagnetic wave absorbing capacity

Porous three-dimensional Si C/melamine-derived carbon foam(3 D-Si C/MDCF)composite with an original open pore structure was fabricated by the heat treatment of the commercial melamine foam(MF),carbonization of the stable MF,and chemical vapor deposition of the ultra-thin Si C coating.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)were employed to detect the microstructure and morphology of the as-prepared composites.The results indicated that the 3 D-Si C/MDCF composites with the coating structure were prepared successfully.The obtained minimum reflection loss was–29.50 d B when the frequency and absorption thickness were 11.36 GHz and 1.75 mm,respectively.Further,a novel strategy was put forward to state that the best microwave absorption property with a thin thickness of 1.65 mm was gained,where the minimum reflection loss was–24.51 d B and the frequency bandwidth was 3.08 GHz.The excellent electromagnetic wave absorption ability resulted from the specific cladding structure,which could change the raw dielectric property to acquire excellent impedance matching.This present work had a certain extend reference meaning for the potential applications of the lightweight wave absorption materials with target functionalities.

Effects of additive NaI on electrodeposition of Al coatings in AlCl_(3)-NaCl-KCl molten salts

Effects of NaI as an additive on electrodeposition of Al coatings in AlCl_(3)-NaCl-KCl(80-10-10 wt-%)molten salts electrolyte at 150°C were investigated by means of cyclic voltammetry,chronopotentiometry,scanning electron microscopy and X-ray diffraction(XRD).Results reveal that addition of NaI in the electrolyte intensifies cathodic polarization,inhibits growth of Al deposits and increases number density of charged particles.The electrodeposition of Al coatings in the AlCl_(3)-NaCl-KCl molten salts electrolyte proceeds via three-dimensional instantaneous nucleation which however exhibits irrelevance with NaI.Galvanostatic deposition results indicate that NaI could facilitate the formation of uniform Al deposits.A compact coating consisting of Al deposits with an average particle size of 3μm was obtained at a current density of 50 mA∙cm^(−2) in AlCl_(3)-NaCl-KCl molten salts electrolyte with 10 wt-%NaI.XRD analysis confirmed that NaI could contribute to the formation of Al coating with a preferred crystallographic orientation along(220)plane.