X. Nie

Preparation and characterization of highly flexible Al 2 O 3 /Al/Al 2 O 3 hybrid composite

The natural brittleness of oxide ceramics heavily inhibits their more extensive applications. In present research, a highly flexible Al2O3/Al/Al2O3 hybrid composite was fabricated by employing plasma electrolysis oxidation to in situ grow alumina layers on Al foil, in which an outside layer of nanostructured polycrystalline oxide ceramic was composed of nanosized grains with the size of around 17 nm. Due to shear band formation, nanosized circle bubbles prolonging the crack path, grain rotation, and deformation, the fabricated Al2O3/Al/Al2O3 hybrid composite contains no observable cracks even after being bent on a cylindrical bar with a curvature of 1.5 mm. The composite exhibits alumina stiffness at the elastic stage and aluminum ductility during plastic deformation, which provides high flexibility with the well-integrated properties of the components. In a synergistic interaction, the alumina on the outside exhibited a strain of 0.33% at room temperature, which was higher than optimum value of 0.25% presented by reported most flexible oxide ceramics. With the unique characteristics and properties, the Al2O3/Al/Al2O3 composite demonstrates a great potential for various engineering applications.

Grain structure development and eutectic solidification of discontinuous magnesium borate whisker reinforced AA2024 matrix composite

Abstract In the present research, the solidification behaviour of MBO whisker reinforced 2024 aluminium alloy matrix composite (MBO/AA2024) was studied by employing computer based thermal analysis, scanning electron microscopy and differential scanning calorimetry. The results show that the addition of MBO whiskers refines the grain structure in the matrix of the MBO/AA2024 composite. The nucleation of primary α-Al phase took place away from the whisker surfaces and started within the interstice of whiskers. The whiskers had almost no significant influence on the refinement of the eutectic phases. Dans cette recherche, on a étudié le comportement de solidification du composite (MBO/AA2024) à matrice d’alliage d’aluminium 2024 renforcée par des barbes de MBO, au moyen de l’analyse thermique automatisée, de la microscopie électronique à balayage et de l’analyse calorimétrique à compensation de puissance. Les résultats montrent que l’addition de barbes de MBO affine la structure de grain dans la matrice du composite MBO/AA2024. La nucléation de la phase primaire α-A1 prenait place à l’écart des surfaces de la barbe et commençait à l’intérieur de l’interstice des barbes. Les barbes n’avaient presque pas d’influence sur l’affinement des phases de l’eutectique.