Zongyong Yao

Tsinghua University, Peping, Beijing, China

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Publications (2)4.46 Total impact

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    Qing Liu, Zongyong Yao, Andrew Godfrey, Wei Liu
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    ABSTRACT: The effect of second-phase particles on the evolution of the deformation microstructure during cold rolling of the particle-containing aluminum alloy AA3104 has been investigated using electron channeling contrast imaging and electron backscattered diffraction (EBSD). The results show that the influence of second-phase particles on the deformation microstructure depends on the particle size. Fine dispersoids present in the microstructure have no clear effect on the grain orientation dependence of the dislocation structures formed in the strain range examined. However, large scale structural heterogeneities, in the form of deformation zones, are formed near coarse constituent particles, leading to significant local distortions of the deformed microstructure. Analysis of EBSD data shows that significant orientation gradients are found in the vicinity of the coarse particles. Within the deformation zones the largest lattice rotations occur at the tips of plate-shaped constituent particles. A symmetrical pattern of TD-rotations of alternating sign is found in the deformation zones, with the magnitude of the lattice rotations increasing with increasing strain.
    Journal of Alloys and Compounds 08/2009; 482(1):264-271. DOI:10.1016/j.jallcom.2009.03.183
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    ABSTRACT: The evolution of the dislocation boundary structure during the cold rolling of the AA3104 aluminum alloy has been investigated using electron channeling contrast (ECC) imaging and electron backscattered diffraction (EBSD) techniques. The results show that there is a strong correlation between the dislocation boundary structure and the grain orientation. No strong effect of strain level or second-phase particles on the structure-orientation correlation is found. Based on these observations, the microstructures can be classified into one of three types: type A grains, containing two sets of geometrically necessary boundaries (GNBs), type B grains, containing one set of GNBs, and type C grains, consisting of a structure of large dislocation cells. Grains with a type A microstructure have orientations near the copper, brass, and Goss orientations; grains with a type B microstructure are primarily near the S orientation; and grains with a type C microstructure have orientations near the cube orientation. The alignment of the extended dislocation boundaries depends strongly on the grain orientation. In most grains, the boundaries are parallel to the traces of the most active {111} slip planes, as identified by a Schmid factor analysis.
    Metallurgical and Materials Transactions A 06/2009; 40(6):1487-1497. DOI:10.1007/s11661-008-9777-x