Papers by Keyword: Eutectic Growth

Abstract: Nickel layer electroless deposited on aluminum substrate was alloyed by Nd-YAG pulsed laser irradiation. Solidification microstructure was characterized through cross section, showing typical microstructure that were located in upper and middle melted zone and interface of melted pool and substrate, respectively. The microstructure was analyzed by transmission electron microscopy (TEM). Followed by the observations, the eutectic growth process was analyzed.

Abstract: By introducing self-pressure processing into combustion synthesis under high gravity, Al2O3-ZrO2(4Y) eutectic composite ceramics without shrinkage cavities and holes were achieved, and the self-pressure processing also made the macro-crack be controlled and the ceramic densification be promoted evidently. XRD results showed the eutectic ceramics were composed of α-Al2O3, t-ZrO2 and a few m-ZrO2 phases, and the volume fraction of the transformable t-ZrO2 increased with self-pressure force increasing. SEM images showed that with increasing self-pressure force, the rod-shaped eutectic colonies were refined and the volume fraction of the colonies increased. Meanwhile, the irregular ZrO2 crystals around eutectic colonies transformed to be fine t-ZrO2 spherical crystals gradually, and thickness of eutectic colonies decreased. With the changes in microstructures of the ceramics, the mechanical properties of the ceramics were improved greatly.

Abstract: The Al2O3/YSZ eutectic composite ceramics-lined pipes have been prepared by combustion synthesis. By adding ZrO2 (4Y) to the thermit, the influences of centrifugal force and eutectic composition on the microstructure, mechanical properties, strengthening and toughening of ceramics lining are researched. The growth of melt is based on eutectic transformation under high degree of under-cooling at centrifugal force above 200G. The linings are comprised of rod-shaped Al2O3 matrix eutectic grains. The diameters of tetragonal lattice ZrO2 fiber in rod-shaped grains are on nano-micron scale. Causing the strengthening and toughening of ceramics to be promoted, and the Al2O3/YSZ eutectic composite ceramics-lined pipes have high comprehensive mechanical properties.

Abstract: Coupled, regular eutectic growth of α(Al) and Al2Cu from ternary Al-Cu-Ag liquid alloys is investigated with focus on the formation and the characteristics of eutectic cells in unidirectionally solidified, polycrystalline, bulk samples. The topologic anisotropy of the lamellar eutectic leads to destabilization along the lamellae with elongated cells being intermediate to stable cells, irrespective of the crystallographic orientation of the phases. The formation of stable cellular patterns with elongated or regular cell structure is explained with reference to the crystal orientation of the phases α(Al) and Al2Cu, measured by electron backscatter diffraction (EBSD).