Effect of Al2Nd intermetallic phase on the microstructure and properties of Mg-Al-Nd alloys.

Introducing of thermodynamically stable strengthening phases is an important means enhancing the properties of magnesium alloys. To introduce a stable Al₂Nd strengthening phase, the Mg-Al-Nd alloys were prepared with a fixed atomic ratio of 2:1 for Al and Nd. The total content of Al and Nd was varied at 1%, 3%, 5%, and 7%, respectively. The effects of Al₂Nd phase on the microstructure and mechanical properties of the Mg-Al-Nd alloys were systematically studied in this work. The experimental results indicated that the as-cast alloy primarily consisted of the acicular Al₁₁Nd₃ phase as a secondary phase. After undergoing a homogenization treatment at 500 °C for 12 h, the secondary phase underwent a transformation, resulting in the formation of short rod shape Al₂Nd structures. Simultaneously, layered Al₂Nd precipitated within the α-Mg matrix. The formation of twinning was inhibited, while the Al₂Nd phase promoted recrystallization and refined the microstructure through the mechanism of particles stimulated nucleation (PSN), as the Al and Nd contents increased during thermal deformation. At the same time, the increases of Al₂Nd phase can enhance the strength and the plasticity of the alloy. The mechanical properties of extruded Mg-1.36Al-3.64Nd (AE5) alloy were excellent with yield strength of 175 MPa, ultimate tensile strength of 249 MPa, and the elongation of 15.4%. The enhanced performance can be primarily attributed to the refined microstructure and the presence of Al₂Nd precipitates with small size, which contributed to effective fine grain strengthening and secondary phase strengthening. [ABSTRACT FROM AUTHOR]