Effect of the various modifiers on the durability of alloys of eutectic silumine

The aim of the study is to provide more quality castings, using new means and introducing new elements in the shape of modifiers of piston alloy AlSi12CuMgNi, as well as providing the more economical production process. During the experiment two groups of pistons were casted in the same conditions. The first group of pistons was modified, with sodium, and the second group with strontium. The casting was performed in three phases, for both groups. The first casting was performed after modifying the material; the second 90 minutes after modifying and the third 180 minutes after modifying. The tensile characteristics, hardness and microstructure were examined on the casted and equally heat treated pistons. The control of the mechanical properties and microstructure showed that period of modifying for pistons modified with sodium lasts 90 minutes, and in the case of pistons modified with strontium, there are no changes, not even after 180 minuets after modifying. (Original)