This work is dealing with the impact of molybdenum on the structure properties of commercial cast AlSi10Mg(Cu) alloy. The solidification path of AlSi10Mg(Cu) alloy with various content of molybdenum has been investigated using cooling curve techniques. The samples for testing have been poured into permanent steel mold. The content of molybdenum has been varied from 0 to 0.20 wt. %.The desired chemical composition was achieved by adding of master alloy AlMo10 into commercial AlSi10Mg(Cu) alloy. The micro hardness of as cast alloys with different content of molybdenum has been measured. The microstructure and EDX analysis from the casted samples has been carried out. The results show that molybdenum in commercial AlSi10Cu(Mg) alloy precipitate in the interdendritic region isolated in the form of Al(FeMnMoMg)Si rich intermetallic. The increased content of molybdenum increase slightly liquidus temperature, prolonging precipitation of the last eutectic and surprisingly decrease the micro hardness of commercial alloy for approximately 16 %.

The impact of small addition of zirconium in hypoeutectic commercial AlSi10MgCu alloys on their mechanical properties (hardness) in as cast and thermally treated conditions was investigated. Small addition of zirconium does not change significantly the as cast and heat-treated microstructure of investigated alloys except to reduce the SDAS and grain size of primary α-aluminium phases. Addition of zirconium up to 0.14 wt. percentage increases the hardness of investigated alloys in as cast conditions. The increase in the hardness of samples after various solid solution times can correlate very well with the formation of small needle like coherent Al3Zr particles.

Comprehensive understanding of the melt quality is of vital importance for foundry man. The effect of each particular element need to be properly analysed. Therefore, the aim of this paper was to analyse the impact of various content of zirconium on the solidification path and structural characteristics (SDAS, grain size, porosity) of as cast commercial AlSi10MgCu alloys. It has been found that addition of zirconium up to 0.24 wt.% reduce significantly the grains size (from 3.5 mm to 1.2 mm), SDAS (from 57.3 µm to 50.4 µm) and porosity (from 19% to 5%), leading to production of sound cast parts.