Thermophysical properties and microstructure of magnesium alloys of the Mg-Al type

Abstract

Generally speaking, magnesium alloys of the Mg-Al type are used as structural materials, but their disadvantage lies in their low heat resistance. The addition of suitable alloying elements can be positive, as it makes it possible to achieve good thermo-mechanical properties. For the application of a specific material for thermally stressed cast parts it is necessary to consider the extent of their linear and volumetric changes at elevated and high temperatures. The aim of this paper is to study the behaviour of selected magnesium alloys based on Mg-Al during heat stress conditions in order to simulate real conditions using dilatometric analyses. These properties were evaluated on samples of alloys prepared by gravity casting in metallic moulds. The effect of the metallurgical processing of the alloys on the studied parameters was also investigated. Keywords: castings, magnesium alloys, thermophysical properties, microstructure V splo{nem se zlitine Mg-Al uporabljajo kot konstrukcijski materiali, toda njihova pomanjkljivost je, da imajo majhno toplotno odpornost. Dodatek ustreznih zlitinskih elementov pozitivno vpliva na izbolj{anje njihove toplotne stabilnosti oz. odpornosti. Pri uporabi nekega materiala, ki bo toplotno obremenjen, moramo upo{tevati njegove linearne in volumenske spremembe pri povi{anih in visokih temperaturah. Namen tega prispevka je {tudij vedenja izbranih Mg-zlitin tipa Mg-Al med toplotnimi obremenitvami, da bi tako simulirali njihovo vedenje v realnih razmerah. Njihovo vedenje smo analizirali z dilatometri~nimi analizami na vzorcih zlitin, ki so bili izdelani z gravitacijskim litjem v kovinskih modelih. Raziskovali smo tudi vpliv metalur{kih procesov na izbrane zlitine.