As excellent lightweight engineering materials, Mg-Sc alloys also exhibit shape memory effects. With less than 25 atomic percent Sc in Mg, the martensitic transformation was found to occur at temperatures 173 K–183 K, far below the room temperature. Based on both experimental observations and first-principles density functional calculations, we found that tuning the chemical ordering and hence the microstructure of Mg-Sc precipitates, the martensitic transformation temperature ($M_{\mathrm{S}}$) can be systematically elevated. The $M_{\mathrm{S}}$ associated with layered nanoprecipitates of a B2 variant phase coherent with Mg matrix is about 184 K ($M_0$), no superior to chemically disordered nanoprecipitates. However, when the double-layered B2 variant phase decomposes into two layers separated by one layer of Mg atoms, the transformation temperature can be raised up to 218 K, 34 K above the $M_0$. Further separating the Sc-rich layers may eventually leads to chemical compounds of homogeneous chemical orders, indicating a $M_{\mathrm{S}}$ of 291 K, approaching the room temperature. Our calculations suggest that when chemical ordering is modulated in such a way, increased ground-state energy difference and decreased vibrational free energy difference between austenite and martensite contribute mainly to the stabilized phase transformations. Our results help to understand the transformation mechanisms and provide a feasible approach to elevate $M_{\mathrm{S}}$ experimentally, in particular, aiming for bio-applications of shape memory Mg-Sc alloys.

作为优良的轻质工程材料，镁-钪合金还表现出形状记忆效应。由于 Mg 中 Sc 的原子百分比低于 25%，马氏体转变被发现发生在 173 K–183 K 的温度下，远低于室温。基于实验观察和第一性原理密度泛函计算，我们发现调节 Mg-Sc 析出物的化学顺序和微观结构，马氏体转变温度 (${米}_{\mathrm{小号}}$) 可以系统地提升。这${米}_{\mathrm{小号}}$与与 Mg 矩阵相干的 B2 变体相的层状纳米沉淀物相关的约为 184 K（${米}_0$), 并不优于化学无序的纳米沉淀物。然而，当双层 B2 变相分解为由一层 Mg 原子隔开的两层时，转变温度可以提高到 218 K，比 B2 高 34 K。${米}_0$. 进一步分离富 Sc 层可能最终导致化学化合物具有均匀的化学顺序，表明${米}_{\mathrm{小号}}$291 K，接近室温。我们的计算表明，当以这种方式调制化学有序时，奥氏体和马氏体之间基态能差的增加和振动自由能差的减少主要有助于稳定相变。我们的结果有助于理解转化机制并提供一种可行的方法来提升${米}_{\mathrm{小号}}$在实验上，特别是针对形状记忆 Mg-Sc 合金的生物应用。