Formation of magnesium-eutectic mixture layered composite

The work was started from study of the structural transformations, that in elevated temperatures, take place at the magnesium-aluminium interface. It was found experimentally that at temperature of 445oC solid state diffusion is followed by liquid phase appearance at the Mg-Al interface. For process passing with the liquid phase contribution thickness d of the reactions products against the time t can be expressed by the equation d=Atn with the time exponent value n>1. This process is very fast compared to solid state polyphase diffusion and can be controlled, therefore may be used for fabrication of layered composite. To obtain a composite, magnesium and aluminium sheets are formed alternately into a pocket and then heated at temperature of 445oC. Heating is prolonged for passing all the aluminium with part of the magnesium sheets into a liquid phase. During solidification liquid phase is transformed into eutectic mixture. So, composite that was formed consists of alternating magnesium and eutectic mixture layers. Using X-ray microprobe analysis and on the basis of Mg-Al binary phase diagram we were found that the eutectic mixture contains two phases: Mg17Al12 intermetallic compound and solid solution of aluminium in magnesium.