Three-dimensional observation and image-based modelling of thermal strains in polycrystalline alumina

作     者：Gonzalez, D. King, A. Mostafavi, M. Reischig, P. du Roscoat, S. Rolland Ludwig, W. da Fonseca, J. Quinta Withers, P. J. Marrow, T. J. 

作者机构：Univ Manchester Sch Mat Manchester M13 9PL Lancs England Univ Oxford Dept Engn Sci Oxford OX1 3PJ England ESRF F-38000 Grenoble France Univ Oxford Dept Mat Oxford OX1 3PH England Univ Grenoble 1 Lab R 3S F-38041 Grenoble France INSA Lyon GEMPPM MATEIS Lyon France 

出 版 物：《ACTA MATERIALIA》 (材料学报)

年 卷 期：2013年第61卷第20期

页      面：7521-7533页

核心收录：

学科分类：0806[工学-冶金工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：EPSRC [EP/K032518/1  EP/H020047/1] Funding Source: UKRI 

主　　题：Alumina Diffraction contrast tomography Synchrotron X-ray residual stress Image-based modelling 

摘      要：Diffraction contrast tomography (DCT) with synchrotron X-rays was used to map the three-dimensional microstructure of alumina. Each grain boundary (GB) of this coarse-grained ceramic was characterized by its orientation and the crystal misorientation of the adjacent grains. The microstructure of alumina was sufficiently well described by DCT to produce a microstructurally representative image-based finite-element model comprising similar to 400 grains. Grain boundary cohesive elements were used to calculate the local thermal stresses acting on each GB arising from the crystal anisotropy. Digital volume correlation of the CT images was used to gauge the degree of bending induced during loading and to extract polycrystalline elastic properties. The model simulations showed the average intergranular stress to be influenced by the orientation of the GB plane relative to the basal planes of the adjacent grains. Boundaries to which at least one of the basal planes was closely aligned tended to develop higher tensile stress;these boundaries were predicted to have a tendency for intergranular fracture. Under compressive loading, the normal stresses of the boundaries that cracked were slight more tensile relative to the general population due to grain-to- grain interactions. The predicted effect of crystal lattice strains and rotations on diffraction, due to the modelled thermal stresses, showed general agreement with the observed X-ray diffraction images of individual grains. (C) 2013 Published by Elsevier Ltd. on behalf of Acta Materialia Inc.