The binary and multicomponent alloys based on magnesium and aluminum have many industrial applications. Because of favorable ratio between the weight and the mechanical properties, the alloys of the series 5XXX, 6XXX or 7XXX in many cases are used in the for the purposes of aircraft, automobile or bicycle industries.
Elements like Fe, Zn, Si, Li, Zr, Cu which frequently are the third, fourth or higher order components of the Al-base or Mg-base alloys are a good example of traditional alloying additions. The separate groups form those elements which are added as modifying additions (ex.: P, Na, Sr, Sb). Recently, it has been pointed out in many cases that some content of Sr plays a very positive role as an agent modifying or improving the casting, mechanical or structural properties
There is no any thermodynamic data in the literature for the liquid Al-Mg-Sr alloys.
With the aid of the concentration cell method, the magnesium activities aMg were measured in liquid Al-Mg-Sr solutions for alloys of the concentrations defined by constant ratio of XAl : XSr = 1:4; 3:2 and 2:3, assuming XMg = const in the range between 0.1 and 0.9, and in the temperatures of T=490÷760°C. Also the points on the liquidus surface were obtained.