Papers by Author: Liang Zuo

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Authors: Liang Zuo, Claude Esling, J. Muller, Emmanuel Bouzy
Authors: W.P. Tong, L.M. Wang, G.J. Ma, N.R. Tao, Liang Zuo
Abstract: A nanostructured surface layer on a pure iron sample was prepared by surface mechanical attrition treatment (SMAT). The thermal stability of SMAT sample was investigated at different temperatures with or without a high magnetic field (H =12T). It was found that a high magnetically annealing enhanced grain growth at the early stage of annealing, and produced a uniform nanocrystalline grain structure. After homogeneous grains developed, further grain growth became restrained.
Authors: Gang Wang, Shi Ding Wu, Yan Dong Wang, Ya Ping Zong, Claude Esling, Liang Zuo
Abstract: Equal channel angular extrusion (ECAE) is an effective means of producing ultrafine-grained materials with extraordinary mechanical properties. Texture evolution and microstructure in pure copper single crystals processed by ECAE for up to five passes via route C are investigated to understand mechanisms of plastic deformation and grain refinement during ECAE. The experimental textures after the third pass ECAE process recovers that after one pass ECAE process. The main textures approaches a stable one after four passes of ECAE process via Route C while the intensity of main texture components decreases gradually. Local TEM-OIM measurements shows that grain subdivision in ECAE-processed samples occurs with the formation of many low angle grain boundaries.
Authors: Y.X. Cai, Y.D. Liu, Yi Nong Wang, Gang Wang, Yan Dong Wang, Fu Hui Wang, Liang Zuo
Abstract: The aim of this work is to investigate the relationship between the deformation microstructure and texture in cold rolled Interstitial Free (IF) steel sheets. In the present research, the cold rolled IF steel sheets with 10%-50% reductions are used to observe the characteristic microstructure and individual orientations by transmission electron microscopy (TEM) and SAED patterns. The experimental results on inter-granular strain homogeneity and dislocation wall formation are given in details in this paper. The results are explained by the analysis of crystallographic gliding and are helpful to improve the prediction of cold rolling textures.
Authors: Yu Dong Zhang, Claude Esling, Xiang Zhao, Liang Zuo
Abstract: In this paper, some of our recent results in phase equilibrium, microstructure, texture and precipitation resulting from the application of an external high magnetic field during diffusional phase transformation in both medium carbon and high carbon steels have been summarized Their potential engineering applications are foreseen.
Authors: Y.H. Sha, S.C. Zhou, Wei Pei, Liang Zuo
Abstract: The influences of different rolling modes and speed ratios on cold rolling texture development, and the characteristics of recrystallization textures after ordinary annealing as well as magnetic annealing have been investigated for non-oriented silicon steel. Results show that the through-thickness deformation textures were effectively changed by asymmetric cold rolling even in the case of small speed ratios, and the recrystallization textures were modified with the enhanced favorable {100} and η (<100>//RD) texture components by magnetic annealing. Much improved magnetic properties can be obtained through optimization of asymmetric rolling and annealing parameters. Thus, application of asymmetric cold rolling and magnetic annealing might open up new possibilities for texture control in high-grade silicon steel production.
Authors: Zong Bin Li, Yu Dong Zhang, Claude Esling, Hao Yang, Ji Jie Wang, Chang Shu He, Xiang Zhao, Liang Zuo
Abstract: For off-stoichiometric Ni2MnGa ferromagnetic shape memory alloys, a large shape change could be induced through the rearrangement of martensitic variants under an external magnetic field. Insight into the orientation relationships of martensitic variants and the characteristics of variant boundaries is thus essential for understanding the magnetic shape memory performance. In this paper, a thorough crystallographic investigation was made on the incommensurate 7M modulated martensite in one polycrystalline Ni50Mn30Ga20 alloy by means of X-ray diffraction and SEM electron backscattered diffraction (EBSD). Locally, there are four differently-oriented martensitic variants, being twin related to one another. The twin interface planes are coherent and they are in coincidence with the respective twinning planes (K1). A primary exploration was performed to improve the microstructure by repeated magnetic field training during phase transition. The present investigation could offer useful guidance to develop specific technique for microstructure optimization.
Authors: Yu Dong Zhang, Zong Bin Li, Claude Esling, Xiang Zhao, Liang Zuo
Abstract: In the present work, we summarized two calculation methods to determine some specific crystallographic elements based on electron diffraction orientation measurements by SEM/EBSD or TEM. The first one is to determine the twin type and twinning elements of crystal twins based on the minimum shear criterion, using the experimentally determined twinning plane for Type I twin and compound twin or twinning direction for Type II twin as initial input. The method is valid for any crystal structure. The second one is one to determine the plane indices of the faceted interfaces where the orientation relationships (ORs) between the adjacent crystals are reproducible. The method requires one prepared sample surface instead of two perpendicular surfaces. These methods are expected to facilitate the related microstructural characterizations.
Authors: Claude Esling, Yu Dong Zhang, Jacques Muller, Xiang Zhao, Liang Zuo
Abstract: In the present work, we summarize three calculation methods to determine some specific crystallographic elements based on electron diffraction orientation measurements by SEM and TEM. The first one is to determine the plane indices of the faceted interfaces where the orientation relation¬ships (ORs) between the adjacent crystals are reproducible. To acquire the orientation data, we need to prepare only one sample surface but not two perpendicular sample surfaces as usually required in the standard double trace method. The second is to characterize the surface crystalline planes and directions of a faceted nano-particle under TEM imaging and diffraction mode. With the determination of the edge trace vectors and then the plane normal vectors in the screen coordinate system of TEM, their Miller indices in the crystal coordinate system can be calculated through coordinate trans¬formation. The third method is to determine the twin type and the twinning elements based on the orientation information acquired by SEM EBSD measurements from the two twinned crystals through misorientation calculations. These methods will facilitate related studies.
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