Magnesium, being the lightest structural metal, faces limitations in alloy development due to its inherently low elastic modulus. Therefore, this study develops high-performance, high-modulus Mg-15Gd-8Y-xAl-0.3Mn (wt.%) (x = 6, 8, 10) alloys and investigates their microstructure and mechanical properties. The findings indicate that the alloys primarily consist of Al₂RE and α-Mg phases, with both the amount and size of Al₂RE phase increasing as the Al content rises. After extrusion, both the grains and the Al₂RE phase are refined. The increased modulus of the alloys is mainly due to the formation of the high-modulus Al₂RE phase. When the Al content is 6 %, 8 %, and 10 %, the modulus of the alloys is 51.8 GPa, 53.8 GPa, and 56.1 GPa, respectively. Additionally, the Al₂RE and Mg₅RE phases can jointly regulate the microstructure and mechanical properties of the alloys. As the Al content increases, the amount of Al₂RE phase increases, consuming the rare earth elements in the alloy and reducing the nano-precipitated Mg₅RE phase. Consequently, with the increase in Al content, the recrystallization rate increases, and the recrystallized grains become larger. When the Al content is 6 %, the alloy exhibits a bimodal structure with the smallest recrystallized grains, resulting in the highest yield strength of 341 MPa. When the Al content is 8 %, the alloy has a fine, fully recrystallized structure, leading to a relatively high elongation of 9.1 %. These findings provide valuable insights for designing high-modulus magnesium alloys with optimized yield strength and elongation for structural applications.

中文翻译：

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高模量镁合金：通过原位合成 Al2RE 相控制微观组织和机械性能


镁是最轻的结构金属，由于其固有的低弹性模量，在合金开发方面面临限制。因此，本研究开发了高性能、高模量的 Mg-15Gd-8Y-xAl-0.3Mn （wt.%） （x = 6， 8， 10） 合金，并研究了它们的微观组织和机械性能。结果表明，合金主要由 Al₂RE 和 α-Mg 相组成，随着 Al 含量的增加，Al₂RE 相的数量和尺寸都会增加。挤压后，晶粒和 Al₂RE 相都经过细化。合金模量的增加主要是由于高模量 Al₂RE 相的形成。当 Al 含量为 6 %、8 % 和 10 % 时，合金的模量分别为 51.8 GPa、53.8 GPa 和 56.1 GPa。此外，Al₂RE 和 Mg₅RE 相可以共同调节合金的微观组织和机械性能。随着 Al 含量的增加，Al₂RE 相的量增加，消耗合金中的稀土元素并减少纳米沉淀的 Mg₅RE 相。因此，随着Al含量的增加，再结晶速率增加，再结晶的晶粒变得更大。当 Al 含量为 6 % 时，合金表现出双峰结构，具有最小的再结晶晶粒，从而产生 341 MPa 的最高屈服强度。当 Al 含量为 8 % 时，合金具有精细的、完全再结晶的结构，导致 9.1 % 的相对较高的伸长率。这些发现为设计具有优化屈服强度和伸长率的高模量镁合金用于结构应用提供了有价值的见解。