The insightful understanding of phase transition in rare earth elements under shock compression is significant to the future development of materials science. In this work, a new reliable Finnis-Sinclair interatomic potential for hexagonal close-packed (HCP) single crystal yttrium (Y) is developed and validated. The potential reproduces the phase transition sequence of HCP → Sm-type (samarium-type) → DHCP (double hexagonal-close-packed) → FCC (face-centered-cubic) of Y observed in high-pressure experiments. Further, large-scale NEMD simulations are conducted to study shock compression behaviors of Y. For the [10−10]_HCP shock direction, the HCP → Sm-type phase transition occurs via an intermediate metastable BCC structure, which is accomplished by atomic shuffles and shear. Then, a pure-shear along the [10−10]_Sm-type direction transforms the Sm-type to DHCP structure. Besides, we find FCC phase can be generated by shifting the atoms at two layers in opposite <10−10> directions on {0001} planes in the DHCP lattice. Combined with the transition state theory, we confirm these transition pathways follow the minimum energy path. For shock along the [0001]_HCP and [−12−10]_HCP directions, the HCP → FCC phase transition is mediated by the amorphization which subsequently annihilates and turns to recrystallize to be FCC lattice. The results suggest that the uniaxial compression strain along the [0001]_HCP and [−12−10]_HCP directions hinders the formation of Sm-type and DHCP phases. Our findings provide essential insights into the phase transition behavior of Y under shock loading.

对冲击压缩下稀土元素相变的深刻理解对材料科学的未来发展具有重要意义。在这项工作中，开发并验证了一种新的可靠的六方密排 (HCP) 单晶钇 (Y) Finnis-Sinclair 原子间势。电位重现了高压实验中观察到的Y的HCP→Sm型（钐型）→DHCP（双六方密排）→FCC（面心立方）相变序列。此外，还进行了大规模 NEMD 模拟以研究 Y 的激波压缩行为。对于 [10−10] _HCP激波方向，HCP → Sm 型相变通过中间亚稳 BCC 结构发生，这是通过原子混洗实现的和剪切。然后，沿 [10−10] 的纯剪切_Sm-type方向将Sm-type 转换为DHCP 结构。此外，我们发现 FCC 相可以通过在 DHCP 晶格的 {0001} 平面上以相反的 <10-10> 方向移动两层原子来产生。结合过渡态理论，我们确认这些过渡路径遵循最小能量路径。对于沿 [0001] _HCP和 [−12−10] _HCP方向的激波，HCP → FCC 相变由非晶化介导，非晶化随后湮灭并转为重结晶成为 FCC 晶格。结果表明，沿 [0001] _HCP和 [−12−10] _{HCP的单轴压缩应变}方向阻碍了 Sm 型和 DHCP 阶段的形成。我们的研究结果为 Y 在冲击载荷下的相变行为提供了重要的见解。