Study of Solidification Thermal Analysis, Microstructure and Mechanical Characteristics of A384 Cast Alloy Treated with Rare Earth (Sm, Tb, Ce and La) Elements

This article investigates the refining and modification response of cast A384 aluminium alloy induced by the addition of rare earth elements and the impact on microstructural and mechanical performance. Thermal analysis technique is used to develop cooling curves, and the first and second derivatives were obtained for each solidification cooling curve and used to identify the sequence of reactions and phase crystallization during solidification without and with Sm and/or Tb or La and/or Ce additions. Microstructural characteristics, hardness, strength, wear and corrosion resistance are evaluated. Optical and SEM observations in addition to EDS analysis provided more details regarding the intermetallic precipitates formed, which revealed the presence of intermetallic phases rich in Sm and/or Tb as well as Ce and/or La. It is observed that the added rare earth metals Sm plus Tb to A384 alloy improved the alloy strength and hardness due to their refining and modification effect. Furthermore, enhancement of both wear and corrosion resistance is achieved through the addition of 1.0 wt.% Samarium (Sm) to A384 samples.