Preliminary studies of the interface strain field in an Al-Al2O3 composite by means of convergent-beam electron diffraction

Abstract

Various kinds of composite materials have been extensively studied concerning their manufacture processing and applications in recent years. Among them, metallic composite materials have drawn extensive attention, because they can offer selected physical, chemical and mechanical properties which cannot be obtained with traditional alloys, ceramics or organic matrix composites. The interfaces in the composites play an important role in the properties of the composite. Up to now, the studies on the interfaces have been mainly limited in the interface morphologies, interfacial reaction products and orientation relationship between the reinforcing phase, crystalline reaction products and the matrix. However, differences in thermal expansion between the reinforced phase and the matrix, generate residual stresses which may affect the aging characteristics of the matrix and the mechanical properties of such composites. Efforts have been made to measure the local lattice strain in the vicinity of the interface, quantitatively by contrast simulation and by detecting the movements of the higher order Laue zone (HOLZ) lines in conventional convergent-beam electron diffraction (CBED). As the electron probe is very close to the interface, HOLZ lines often become obscure or even split. In such cases, it is very difficult to measure the movements of HOLZ lines. Nevertheless, itmore » is possible to measure the strain by matching a dynamical simulation to the experimental splitting of HOLZ lines. Large-angle CBED (LACBED) combines real space and reciprocal space information. A single LACBED pattern shows directly the spatial variation of the lattice strain. The purpose of the present work is to explore the possibility of studying the interface strain field in composite materials according to the shifts and splittings of HOLZ lines by means of improved LACBED technique.« less