The heterogeneities in tensile properties, microstructural characteristics, solute concentrations, and defects levels were studied for the castings with different thicknesses made by high pressure die-cast Al-Mg-Si alloys. For the local mechanical properties in the die-castings, the casting skin provided the highest, whereas the casting centre provided the lowest yield strength, UTS and elongation. The yield strength, UTS and elongation were significantly decreased towards the casting centre.

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... e microstructural heterogeneity is characterised by the segregation of coarse fragmented dendrites, the reduction of solute concentrations of Mg and Si, and the increase of porosity level from the surface to the centre of castings. The growth velocities of eutectic α-Al phase estimated using the Jackson-Hunt model confirm that the growth variation is larger in the thin castings than that in thick castings.