Nowadays improvements in aluminium alloys casting quality have achieved very high levels and comply with reliability requirements for structural and safety components for transport field, particularly the automotive one. Gravity casting and low pressure diecasting are foundry processes commonly used for the production of automotive components, while thixocasting is an emerging system claiming for a number of advantages. The comparison of the three different technologies in terms of microstructural and mechanical properties of as-cast components with similar geometry, thickness and weight, is the aim of this work. For the comparison of mechanical properties, ultimate tensile strength (R{sub}(m)), yield stress (R{sub}(p02)), elongation (A%) and hardness (HV) were investigated; moreover, fracture mechanics tests have been carried out on pre-cracked specimens. The microstructure was characterised by quantitative metallography taking into account primary aluminium dendrite size and arm spacing (DAS), morphology and size of eutectic silicon, second phase particles and intermetallics. Porosity and shrinkage cavities were as well quantitatively assessed. The reported results belong to a wide research work aiming at assessing the overall mechanical reliability of aluminum-silicon castings, including their resistance against unstable fracture; relationships between casting and defects size and mechanical behaviour have been established.
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