Liu Chenyue, Xu Guanglong, Chen Fuwen
College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211816, China.
Materials (Basel). 2025 Aug 15;18(16):3828. doi: 10.3390/ma18163828.
Mg-Sc body-centered cubic (BCC) phase-structured alloys not only exhibit superior room-temperature ductility and quasi-isotropic deformation behaviors compared to conventional hexagonal close-packed (HCP) Mg alloys in mechanical applications, but they also demonstrate a shape-memory effect that is applicable to intelligent devices. Due to the introduction of a dual-phase microstructure feature, the unveiled strengthening/toughening mechanism, and the potential benefit of Sc alloying in BCC creep deformation, it is necessary to investigate the composition and time-dependent creep behaviors of BCC Mg-Sc alloys, such as creep resistance and strain rate sensitivity at room temperature, through nano-indentation on the Mg-Sc diffusion couple. A critical finding is that as the Sc content increases from 23.01 at.% to 33.56 at.%, the BCC Mg-Sc alloy exhibits a progressive enhancement in creep resistance at room temperature, evidenced by the creep stress exponent () rising from 49.02 to 66.22. Furthermore, the strain rate sensitivity () increases from 0.02 at 26.94 at.% Sc to 0.11 at 32.63 at.% Sc, along with the Sc composition gradient. These phenomena can be attributed to the formation of ordered structures with the increasing Sc concentration, which introduce short-range local barriers to dislocation motion, as confirmed through atomic-scale microstructural analysis.
与传统的六方密堆积（HCP）镁合金相比，Mg-Sc体心立方（BCC）相结构合金在机械应用中不仅表现出优异的室温延展性和准各向同性变形行为，而且还展现出适用于智能设备的形状记忆效应。由于引入了双相微观结构特征、揭示了强化/增韧机制以及Sc合金化在BCC蠕变变形中的潜在益处，有必要通过对Mg-Sc扩散偶进行纳米压痕来研究BCC Mg-Sc合金的成分和随时间变化的蠕变行为，例如室温下的抗蠕变性和应变速率敏感性。一个关键发现是，随着Sc含量从23.01原子百分比增加到33.56原子百分比，BCC Mg-Sc合金在室温下的抗蠕变性逐渐增强，这由蠕变应力指数（）从49.02上升到66.22证明。此外，应变速率敏感性（）随着Sc成分梯度从26.94原子百分比Sc时的0.02增加到32.63原子百分比Sc时的0.11。这些现象可归因于随着Sc浓度增加而形成的有序结构，通过原子尺度微观结构分析证实，这些结构对位错运动引入了短程局部障碍。
