Imaging damage evolution in a small particle metal matrix composite

Abstract

It is difficult to study effectively microstructural damage in metal matrix composites (MMCs) due to artefacts arising from traditional metallographic sample preparation techniques. The sectioning and imaging capabilities of the focused ion beam (FIB) microscope provide an excellent method for studying damage accumulation in MMCs. The capabilities of the FIB system have been used to carry out a study of damage evolution in a powder-processed/hot-extruded Al2080/SiCp MMC. Microvoid damage is found to be preserved accurately during FIB sectioning, allowing measurements of the fraction of decohered particles and the void area fraction. These microscopic damage measurements are correlated with the macroscopic damage parameter, D, as determined by density measurements. Using transmission electron microscopy, the evolution of dislocation structures at the SiC-matrix interfaces has been examined. A previously unreported decohesion mechanism has been observed.

Introduction to Focused Ion Beams

“…Evans et al (1999) discuss FIB imaging of deformation and damage in tensile tested Al-based MMCs, also showing results of FIB TEM preparation. Evans et al (1999) discuss FIB imaging of deformation and damage in tensile tested Al-based MMCs, also showing results of FIB TEM preparation.…”

FIB Imaging of Deformation in Aluminum Alloys for Advanced Automotive Applications

“…Applications of FIB imaging to the direct observation of deformation in metals are less well reported [3][4][5][6], but the effectiveness of the FIB technique as a tool to directly image the degree or extent of deformation is becoming accepted in industrial research and development.Particularly for FCC metals, FIB secondary electron (and to a lesser extent secondary ion) images are sensitive to increased dislocation density and the presence of subgrain boundaries, revealing a "mottled" and less uniform contrast as the degree of deformation within a grain increases. This makes FIB imaging a useful and efficient means of evaluating large areas that would be impractical to observe by transmission electron microscopy (TEM).…”

“…Focused ion beam (FIB) imaging of metals reveals a remarkable degree of grain orientation contrast [1,2 and incorporated references]. Applications of FIB imaging to the direct observation of deformation in metals are less well reported [3][4][5][6], but the effectiveness of the FIB technique as a tool to directly image the degree or extent of deformation is becoming accepted in industrial research and development.…”

Assessment of Deformation using the Focused Ion Beam Technique

“…FIB secondary electron imaging has been successfully employed to detect plastic deformation in metal matrix composites. (2,3) Sections away from the deformed surface were also prepared and imaged using the FIB. Fig.…”