Effect of Mn on Microstructure and High-temperature Properties of Mg-Y-Al Alloy

This study systematically explores the impact of Mn on the microstructural characteristics, mechanical performance under elevated temperature conditions, and creep properties exhibited by Mg-Y-Al alloys. The experimental findings indicate a gradual augmentation in the alloy's grain size in correlation with an increment in Mn content. In contrast, the second phase in the structure does not change, which is still composed of Mg₂₄Y₅, Al₂Y, and LPSO/SFs phases. The introduction of Mn into the alloy leads to an increased orientational divergence between Al₂Y and α-Mg, consequently reducing the potency of Al₂Y in nucleation. The alloy with Mn improves the strength of the high temperatures. At 300 °C, the alloy containing 0.6 wt.% Mn achieves a ultimate tensile strength of 165.7 ± 3.5 MPa, a yield strength of 111.8 ± 2.2 MPa, and an elongation rate of 39.2 ± 2.1%. Within a creep testing environment (300 °C/50 MPa), the alloy's creep properties significantly enhance as the Mn content increases. In contrast to the Mn-free alloy, which exhibits a minimum creep rate of 1.31 × 10^-8 s^-1, the alloy containing 0.9 wt.% Mn demonstrates a substantially lower minimum rate of 2.42 × 10^-9 s^-1, indicating a reduction approximately equivalent to an order of magnitude.