Synergistic Effect of RE (La, Er, Y, Ce) and Al-5Ti-B on the Microstructure and Mechanical Properties of 6111Aluminum Alloy

For aluminum alloys, grain refinement is one of the effective methods for improving both strength and ductility. However, the refining effect of Al-Ti-B master alloy refiners deteriorates due to the agglomeration and sinking of the second phase particles. In this paper, the effects of rare earth type, rare earth content, and holding time on the microstructure and properties of Al-5Ti-B + RE/6111 were investigated by orthogonal experiment. It was shown that the addition of rare earth promoted the transformation of the β-Al₅FeSi phase to anα-Al₁₅(Mn,Fe)₃Si₂ phase, while the segregation of rare earth made it difficult for TiB₂ to aggregate and inhibited the growth of TiAl₃, resulting in more particles becoming effective nucleation substrates. The Al-5Ti-B + Ce master alloy developed based on orthogonal experiment improved the refinement recession problem well and improved the comprehensive mechanical properties of 6111 aluminum alloy. It was found that the addition of Al-5Ti-B + 0.1Ce, which had an ultimate tensile strength of 240.4 ± 2.2 MPa, successfully reduced the grain size by 73.8% and improved elongation by 37.8% compared to the base alloy. There search is of great significance for the preparation and application of high-performance rare earth 6111 aluminum alloy.