The quality of wrought magnesium (Mg) alloys is closely linked to the quality of the cast ingots. Conventionally casting (CC) Mg–2Y ingots exhibit relatively coarse grain sizes. When CC ingots undergo rolling processing (CC-10-R), the resulting Mg–2Y sheets retain coarse grain sizes (∼11.87 μm), while precipitating a small number of Mg₂₄Y₅ nanoparticles (∼0.26%), as well as forming a strong C-type texture (∼10.91). The implementation of controlled diffusion solidification (CDS) effectively refines the grain size of Mg–2Y ingots and increases the content of Mg₂₄Y₅ particles. When CDS is combined with rolling (CDS-10-R), the grain size is refined to ∼5.57 μm, the precipitation of Mg₂₄Y₅ nanoparticles is increased to ∼1.79%, and the C-type texture was weakened to ∼7.74. The CDS-10-R shows an increase in strength of ∼51.8% and an enhancement in plasticity of ∼32.6% compared to CC-10-R. The enhancement in strength is primarily due to fine-grain strengthening (∼42.1% contributions) and precipitating strengthening (∼39.6% contributions). The improvement in plasticity is attributed to the weakening of the {0001} basal texture, which facilitates the activation of <c + a> slips. Compared to other wrought Mg–Y alloys, Mg–2Y sheets produced by combining CDS with rolling possess exceptional strength-plasticity combinations. This finding presents a novel route to achieving high strength and plasticity in low-alloyed rare-earth Mg alloys.

Silicon (Si) is an inevitable impurity element in the AZ31 alloy. In this study, the Si impurity was detected mainly as fine Mg₂Si particles dispersed widely within the central region of the Mg₁₇Al₁₂ phase. During the solidification process, the Mg₂Si particle precipitates at about 565 ℃, before the Mg₁₇Al₁₂ phase of 186 ℃, potentially acting as the heterogeneous nucleation core for the Mg₁₇Al₁₂ phase. The orientation relationship between Mg₂Si and Mg₁₇Al₁₂ was investigated using the Edge-to-Edge matching model (E2EM) calculations, which showed a misfit of only 0.1%. This low misfit suggests that Mg₂Si can serve as a heterogeneous nucleation site for Mg₁₇Al₁₂. The surface and interface structures of Mg₂Si (220) and Mg₁₇Al₁₂ (332) were constructed, and then investigated through the first-principles calculation. The theoretical results indicate that Mg and Al are easily adsorbed on the surface of Mg₂Si, with Al showing higher adsorption energy than Mg. Furthermore, the interface between Mg₂Si and Mg₁₇Al₁₂ exhibits favorable thermodynamic stability. Combined with experiments and theoretical calculations, it is confirmed that the Mg₂Si particles, formed due to the Si impurity, provide effective heterogeneous nucleation sites for the Mg₁₇Al₁₂ phase.