dissertation global and local fracture properties of metal matrix ...

TABLE OF CONTENTS
1. Introduction 5
2. Background 7
2.1. Metal matrix composites as advanced materials 7
2.2. The influence of the global microstructure and the matrix condition
on the global mechanical properties in metal matrix composites 8
2.3. The process of void initiation in materials with particles 9
3. A method to estimate the local conditions for void initiation in materials with
inclusions 15
3.1. An automatic fracture surface analysis system 15
3.2. The determination of the CODi- and CODvi–values 16
3.3. Estimate of the maximum principal stresses in both phases 20
3.3.1. Estimate of the HRR stress tensor at the moment of void initation 20
3.3.2. The determination of the maximum stresses both in the particle and in the
matrix by a Mori-Tanaka type mean-field correction 22
3.3.2.1. The Eschelby approach 22
3.3.2.2. Some general mean-field relations 24
3.3.2.3. Solution procedure 25
4. Local fracture properties of metal matrix composites 29
4.1. Materials for investigation and their mechanical properties 29
4.1.1. Cast MMCs 29
4.1.1.1. Materials characterization 29
4.1.1.2. Tensile tests 30
4.1.1.3. Fracture mechanics tests 32
4.1.2. Powder metallurgy MMC 34
4.1.2.1. Materials characterization 34
4.1.2.2. Compression tests 35
4.1.2.3. Fracture mechanics tests 37
4.1.3. The relation between the mechanical properties 37
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