تاثير عناصر نادر خاكي بر ريز ساختار و خواص مكانيكي آلياژ منيزيم 1و AZ

Effect of rare earth elements on the microstructure and mechanical properties of as cast AZ91 magnesium alloy

AZ91 alloy (Mg-9A1-0.8Zn-0.2Mn) is the most favored magnesium alloy, being used in approximately 90% of all magnesium cast products. It has excellent castability, and sound room-temperature mechanical properties, and in its high purity form (AZ91 R) shows a good corrosion resistance. However, it suffers from low mechanical properties at temperatures in excess of 120°C because of grain boundary phase softening which makes it unsuitable for many of the components in automobile engines. Effect of rare earth metals on the microstructure and mechanical properties of AZ91 magnesium alloy has been studied. The result show after REs were added, a rod-like intermetallic phase-Al1FRE,3 phase-Al„RE3 phase was observed and the volume of Beta(Mg„A112) was somewhat decreased and the morphology of this phase has been modified. These elements have a little effect on room-temperature mechanical properties of AZ91 alloy, but improve the high-temperature mechanical properties.