Sikorski E L, Cusentino M A, McCarthy M J, Tranchida J, Wood M A, Thompson A P
Center for Computing Research, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
Material, Physical, and Chemical Science Center, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA.
J Chem Phys. 2023 Mar 21;158(11):114101. doi: 10.1063/5.0135269.
Tungsten (W) is a material of choice for the divertor material due to its high melting temperature, thermal conductivity, and sputtering threshold. However, W has a very high brittle-to-ductile transition temperature, and at fusion reactor temperatures (≥1000 K), it may undergo recrystallization and grain growth. Dispersion-strengthening W with zirconium carbide (ZrC) can improve ductility and limit grain growth, but much of the effects of the dispersoids on microstructural evolution and thermomechanical properties at high temperatures are still unknown. We present a machine learned Spectral Neighbor Analysis Potential for W-ZrC that can now be used to study these materials. In order to construct a potential suitable for large-scale atomistic simulations at fusion reactor temperatures, it is necessary to train on ab initio data generated for a diverse set of structures, chemical environments, and temperatures. Further accuracy and stability tests of the potential were achieved using objective functions for both material properties and high temperature stability. Validation of lattice parameters, surface energies, bulk moduli, and thermal expansion is confirmed on the optimized potential. Tensile tests of W/ZrC bicrystals show that although the W(110)-ZrC(111) C-terminated bicrystal has the highest ultimate tensile strength (UTS) at room temperature, observed strength decreases with increasing temperature. At 2500 K, the terminating C layer diffuses into the W, resulting in a weaker W-Zr interface. Meanwhile, the W(110)-ZrC(111) Zr-terminated bicrystal has the highest UTS at 2500 K.
钨（W）因其高熔点、热导率和溅射阈值，是偏滤器材料的首选。然而，钨具有非常高的脆性-延性转变温度，在聚变反应堆温度（≥1000 K）下，它可能会发生再结晶和晶粒长大。用碳化锆（ZrC）弥散强化钨可以提高延展性并限制晶粒长大，但弥散相在高温下对微观结构演变和热机械性能的许多影响仍然未知。我们提出了一种用于W-ZrC的机器学习光谱邻域分析势，现在可用于研究这些材料。为了构建适用于聚变反应堆温度下大规模原子模拟的势，有必要对为各种结构、化学环境和温度生成的从头算数据进行训练。通过针对材料性能和高温稳定性的目标函数，对该势进行了进一步的精度和稳定性测试。在优化后的势上，对晶格参数、表面能、体模量和热膨胀进行了验证。W/ZrC双晶体的拉伸试验表明，尽管W(110)-ZrC(111) C端双晶体在室温下具有最高的极限抗拉强度（UTS），但观察到的强度随温度升高而降低。在2500 K时，终止的C层扩散到钨中，导致W-Zr界面变弱。同时，W(110)-ZrC(111) Zr端双晶体在2500 K时具有最高的UTS。
