STUDY OF THE EFFECT OF RARE EARTH ELEMENTS SC, CE AND Y ADDITION ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF AZ91 MAGNESIUM ALLOY: CRITICAL REVIEW

• Main Author: Hamonangan Nasution, Mundzir
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/56621
• Institution: Institut Teknologi Bandung

In the 20th century, magnesium became one of the most developed metals in the world. Magnesium has a high strength to weight ratio which makes it widely used as a structural material. In addition, magnesium has advantages in reducing vibration and heat, biocompatibility, and easy recycling. Therefore, magnesium alloys are widely developed for applications in automotive, aircraft, aerospace, electronic, biomedical, and energy sectors. In the automotive sector, the use of magnesium alloys aims to reduce the mass of the vehicle in order to obtain higher energy efficiency. One of the widely used magnesium alloys is AZ91 because it has better strength and corrosion resistance than other magnesium alloys. However, the use of magnesium is still very limited because they have relatively lower strength compared to steel and have low thermal stability. One way to improve the mechanical properties of magnesium alloys are adding rare earth element. In this study, the effect of the addition of rare earth elements Sc, Ce and Y addition on the microstructure and mechanical properties of the AZ91 alloy will be studied. References related to the research topic were collected and analyzed on the parameters of rare earth element composition, post-casting treatment and microstructure formed after addition of rare earth element. Supporting data such as the thermodynamics of the formation of Al-RE binary phase, the properties of rare earth element on Mg and the strengthening mechanism of AZ91 alloy were also Collected to Complement the analysis of effect of additon Sc, Ce and Y on the AZ91 alloy. As a result, it was found that the addition of a small amount of rare earth element Sc, Ce and Y to the AZ91 alloy had a significant effect on microstructure and mechanical properties. The addition of Sc, Ce dan Y were able to reduce the grain size of the alloy, reduce the amount of ?-Mg17Al12 phase which is the main precipitate in the AZ91 alloy and form an Al-RE binary phase which has high thermal stablilty. The greater addition of Sc, Ce and Y will form finer grains on the alloy. The refinement of the grain size of the alloy, ?-Mg17Al12 phase and formation of the Al-RE intermetallic phase were able to significanly increase the tensile strength, fatigue strength and creep resistance of the AZ91 alloy.