Xinhua Zeng

Behavior of Mg–6Al–xSi alloys during solution heat treatment at 420°C

Abstract The effect of solution heat treatment at 420°C on the morphology of Mg 2 Si particles in Mg–Al–Si alloys was investigated. The Mg 2 Si particles tended to be spherodized during the treatment due to the diffusion of Si atoms along the Mg 2 Si/Mg interface, which is benefit the mechanical properties of the alloys.

Kinetic study on the surface oxidation of the molten Mg-9Al-0.5Zn-0.3Be alloy

Be addition make the oxide film formed on the molten magnesium alloy denser and tougher, thus the burning of the Mg during melting was suppressed. AES was employed to study the composition of the oxide film growing on the surface of the molten Mg-9Al-0.5Zn-0.3Be alloy. It was suggested that the surface oxide film could be divided to two layers: the outer MgO layer and the inner mixed layer consisting of MgO and BeO. Both experimental results and theory analysis indicated that the outer layer grew under parabolic law and the thickness almost kept unchanged during the steady growing state for the inner layer.

YBCO melt-textured growth seeded by NdBCO liquid phase epitaxy thick film

The NdBa2Cu3O7−δ (Nd123) thick film grown by liquid phase epitaxy (LPE) was used as a novel seed to grow the melt-textured (MT) YBa2Cu3O7−δ (Y123) bulk. Taking into consideration the seed size effect on the formation of domain structure, a large dimensional seed was recommended in order to obtain single-domain MT bulks. The melting process of the NdBCO thick film was observed in situ by high-temperature optical microscopy. It can be concluded that the NdBCO LPE thick film has a high thermal stability. In view of the similar lattice constant, the large size achievable, it being free of contamination and having high thermal stability, the NdBCO thick film may be a good candidate for seeding REBCO MT growth.

RE123 epitaxial growth on Sm211 whiskers

Large Sm2BaCuO5 (Sm211) whiskers were grown from Sm–Ba–Cu–O solution. The longest Sm211 fibre reached 4.2 mm in length along its [001] direction. The surface morphologies and microstructures of these Sm211 whiskers were characterized by SEM and HRTEM, respectively, which showed a perfect crystalline structure. Using high temperature optical microscopy, for the first time, the epitaxial crystallization process of Sm123 crystals on the Sm211 whiskers was observed in situ. It was revealed by EDS-attached SEM that SmBCO grains exhibited a c-axis orientation and two different relationships with the Sm211 whisker: and . Furthermore, the Sm211 whisker was tentatively used as a seed for Y123 melt-textured growth, which produced polycrystalline Y123 grains due to the epitaxial relation between Sm211 and Y123.