EFFECTS OF GERMANY AND STRONTIUM ON THE MICROSTRUCTURE AND MECHANO-TECHNOLOGICAL PROPERTIES OF THE AK9M2 ALLOY

Abstract

Foundry aluminum-silicon alloy AK9M2 is widely used in the automotive industry for the casting
of castings for various purposes. This alloy during casting is modified by sodium. However,
the effect of modifying with sodium does not exceed 30–40 minutes, which requires a second operation.
Recently, more and more in the foundry industry when casting from silumin castings, aluminum
ligatures with strontium are used, which are distinguished by a long-lasting effect of preserving
the effect of modifying up to eight or more hours, and also after 2–4 melts.
In this regard, the work presents the results of a study of the effect of joint additions of germanium
and strontium on the mechanical properties of cuprous silumin of grade AK9M2, as well as
the microstructure of alloys. It is shown that the additions of strontium and germanium together provide
a high cooperativity of phase growth in the α-Al–Si eutectic, as well as the hardening of
the α-solid aluminum solution. Germanium and strontium have a modifying effect on the microstructure
of the alloy AK9M2, resulting in an increase in the mechanical properties of the alloys. In this
case, additives up to 0.1–0.3% of germanium increase the fluidity of the AK9M2 alloy by more than
1.3 times. This is accompanied by a decrease in the volume of the concentrated shrinkage shell by
10–12%. The addition of strontium favorably affects the fluidity of the alloy only when the germanium
content is about 0.1% (by mass). The positive effect of germanium on the mechanical and casting
and technological properties of the alloy AK9M2 is enhanced in the presence of strontiu