* Corresponding author. Fax: #86 27 7882661; e-mail: hmzou@whu.edu.cn. Ultramicroscopy 72 (1998) 1—15 Determination of interfacial residual stress field in an Al—Al  O  composite using convergent-beam electron diffraction technique Huamin Zou*, Jun Liu, Di-hua Ding, Renhui Wang, L. Froyen, L. Delaey  Department of Physics, Wuhan University, Wuhan 430072, People+s Republic of China  Beijing Laboratory of Electron Microscopy, Chinese Academy of Sciences, Beijing 100080, People+s Republic of China  Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, de Croylaan 2, B-3001 Leuven-Heverlee, Belgium Received 10 October 1995; received in revised form 7 October 1997 Abstract The interface residual stress field in a particulate reinforced composite Al—Al  O  was studied by means of large-angle convergent-beam electron diffraction (LACBED) technique. When the illuminated area contains an Al  O  particle, the diffraction lines near the ellipsoid-like particle become split. The splitting of diffraction lines maps the spatial variation of the residual strain around the particle. A model for computing the displacement field around a particle in TEM foil was constructed on the basis of Eshelby’s equivalent inclusion method. Taking the equivalent eigenstrain as one of the adjustable parameters, the eigenstrain is determined by fitting the simulated LACBED patterns to the experimental patterns. The factors influencing the LACBED patterns and the accuracy in determination of the strain field with this method are discussed.  1998 Elsevier Science B.V. All rights reserved. PACS: 61.14.Lj Keywords: LACBED; Strain; Interface 1. Introduction Metallic matrix composites reinforced with rigid particles exhibit several advantages over conven- tional alloys due to their increased stiffness, excel- lent tensile strength, and superior creep resistance relative to the matrix materials [1]. These proper- ties make the composites attractive for high-tem- perature applications and other applications in which low-density coupled with high stiffness is desired. The interfaces play an important role in the properties of the composite. Mismatches in the thermal expansion coefficients and elastic moduli between the matrix and the particles give rise to residual stresses in the material upon cooling from the fabrication temperature. The residual stresses 0304-3991/98/$19.00  1998 Elsevier Science B.V. All rights reserved. PII S0304-3991(97)00122-8