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The grain size plays a pivotal role in determining the properties of the alloy. The grain size can be significantly decreased by adding inoculants. Aiming to address the shortcomings of existing inoculants, the Al3Ti-Al2O3/Al inoculant was successfully prepared using Al-Ti master alloy and Al2O3 whiskers as raw materials. With the aid of ultrasonic energy, the Al2O3 whiskers were uniformly dispersed within the inoculants. Under the combined action of ultrasonic and titanium, the Al2O3 whiskers were broken into small particles at high temperature. To enhance the morphology of Al3Ti and achieve even particle dispersion throughout the matrix, vacuum rapid quenching treatment was applied to the inoculant. The SEM test results indicated a significant reduction in particle size after vacuum rapid quenching. The Al3Ti-Al2O3/Al inoculants exhibited excellent grain refinement effects on the weldable Al-Cu-Mn alloy. Crystallographic calculations and HRTEM analysis revealed that Al2O3 and Al have orientation relationships, indicating their potential as effective heterogeneous nucleation sites. The mechanical properties of the Al-Cu-Mn alloy were obviously improved after the Al3Ti-Al2O3/Al inoculant was added. [ABSTRACT FROM AUTHOR]

The potential difference between positive and negative ions was utilized to improve the homogenized dispersion of nanoscale Al2O3 whiskers in Mg matrix composites. The Mg powders were decorated with sodium dodecylbenzene sulfonate (C18H29NaO3S, SDBS) and were introduced to the cathode group on their surface. The Al2O3 whiskers were modified by the cetyl trimethyl ammonium bromide (C19H42BrN, CTAB) and were featured in the anode group. The suitable contents of CTAB and SDBS, the application atmosphere, and the type of solvents were investigated. Dispersion results showed that adding 2wt% SDBS into Mg powders and adding 2wt% CTAB into Al2O3 whiskers promoted the formation of more uniformly mixed composite powders, compared to those of conventional ball milling via scanning electron microscopy (SEM) analysis. Meanwhile, the calculated results derived from first-principle calculations also demonstrated the stronger cohesion between Al2O3 whisker reinforcements and Mg matrix than undecorated composite powders. After preparation by powder metallurgy, the morphology, grain size, hardness, and standard deviation coefficient of composites were analyzed to evaluate the dispersed efficiency. The results indicated that the modification of homogenized dispersed Al2O3 whiskers in composites contributed to the refinement of 26% in grain size and the improvement of 20% in hardness compared with pure Mg, and the reduction of 32.5% in the standard deviation coefficient of hardness compared with the ball-milling sample. [ABSTRACT FROM AUTHOR]

This study simulated the bulk structure and surface energy of Al2O3 based on the density of states (DOS) and studied the synthesis and microstructure of one-dimensional Al2O3 whiskers. The simulation results indicate that the (001) surface has a higher surface energy than the others. The growth mechanism of Al2O3 whiskers follows vapor-solid (VS) growth. For the (001) surface with the higher surface energy, the driving force of crystal growth would be more intense in the (001) plane, and the alumina crystal would tend to grow preferentially along the direction of the (001) plane from the tip of the crystal. The Al2O3 grows to the shape of whisker with [001] orientation, which is proved both through modeling and experimentation. [ABSTRACT FROM AUTHOR]

This study simulated the bulk structure and surface energy of Al₂O₃ based on the density of states (DOS) and studied the synthesis and microstructure of one-dimensional Al₂O₃ whiskers. The simulation results indicate that the (001) surface has a higher surface energy than the others. The growth mechanism of Al₂O₃ whiskers follows vapor-solid (VS) growth. For the (001) surface with the higher surface energy, the driving force of crystal growth would be more intense in the (001) plane, and the alumina crystal would tend to grow preferentially along the direction of the (001) plane from the tip of the crystal. The Al₂O₃ grows to the shape of whisker with [001] orientation, which is proved both through modeling and experimentation., Competing Interests: The authors declare no conflict of interest.