To develop high pressure casting magnesium alloys and to create new ones for use in the automotive industry, to obtain an alloy with suitable solidification range and fluidity during casting, improved castability, high creep resistance, increased mechanical properties, reduced microporosity, increased corrosion resistance and It is very difficult to provide these features at the same time.
"The Mg-Al-Zn alloy system has a very important place in Mg casting alloys. This alloy system was first discovered experimentally in 1913 and then researched and developed by many researchers."
Suitable Magnesium Alloys
Having acceptable cost in alloy selection, having appropriate casting conditions and desired mechanical properties after casting, new alloys containing Al and Zn require the selection of alloying elements such as low amounts of Mn, Si, Ca and Sr and Ce micmetal, and It also limits its use. While magnesium alloys are being developed for pressure casting, the addition of aluminum to the alloy is added to improve casting conditions.
With the addition of aluminum, the f3-beta phase (Mg17Al12), which is a magnesium aluminum eutectic intermetallic, is formed. This phase also significantly reduces the creep resistance, especially above 150 ° C. Thus, in order to prevent the formation of beta phase, elements that will intermetallic with aluminum can be added at higher temperatures before the beta phase is formed. When the phase diagrams of Mg-Me and Mg-Al are analyzed, the rare earth element, alkaline earth element and third group transition elements in the periodic system have this affinity. Another method to prevent beta phase is to reduce the amount of aluminum and at the same time add another element that will create a stable phase with high affinity to magnesium and prevent grain boundary slippage.