Iron-based alloys are widely used as structural components in engineering applications. This calls for a fundamental understanding of their mechanical properties, including those of pure iron. Under operational temperatures the mechanical and magnetic properties will differ from those of ferromagnetic body-centered-cubic iron at 0 K. In this theoretical work we study the effect of disordered magnetism on the screw dislocation core structure and compare with results for the ordered ferromagnetic case. Dislocation cores control some local properties such as the choice of glide plane and the associated dislocation mobility. Changes in the magnetic state can lead to modifications in the structure of the core and affect dislocation mobility. In particular, we focus on the core properties of the $\frac{1}{2}\langle 111\rangle$ screw dislocation in the paramagnetic state. Using the noncollinear disordered local moment approximation to address paramagnetism, we perform structural relaxations within density functional theory. We obtain the dislocation core structure for the easy and hard cores in the paramagnetic state, and compare them with their ferromagnetic counterparts. By averaging the energy of several disordered magnetic configurations, we obtain an energy difference between the easy- and hard-core configurations, with a lower, but statistically close, value than the one reported for the ferromagnetic case. The magnetic moment and atomic volume at the dislocation core differ between paramagnetic and ferromagnetic states, with possible consequences on the temperature dependence of defect-dislocation interactions.

中文翻译：

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从第一性原理计算bcc铁顺磁性状态下的螺钉位错核心结构

铁基合金在工程应用中被广泛用作结构部件。这要求对其机械性能（包括纯铁的机械性能）有基本的了解。在工作温度下，0 K时的机械和磁性能将不同于以铁磁性体为中心的立方铁。在这项理论工作中，我们研究了无序磁性对螺杆位错铁心结构的影响，并与有序铁磁情况下的结果进行了比较。 。位错核心控制一些局部属性，例如滑行平面的选择和相关的位错迁移率。磁态的变化会导致铁心结构发生变化，并影响位错迁移率。特别是，我们专注于$\frac{\mathrm{1个}}{2}〈111〉$顺位状态下螺钉脱位。使用非共线无序局部矩逼近来解决顺磁性，我们在密度泛函理论内执行结构弛豫。我们获得了易磁​​和硬磁在顺磁状态下的位错铁心结构，并将其与铁磁对应物进行比较。通过平均几种无序磁性构型的能量，我们得到了易磁芯构型和硬磁芯构型之间的能量差，其值比铁磁情况低，但在统计上接近。位错核心处的磁矩和原子量在顺磁和铁磁状态之间有所不同，可能对缺陷-位错相互作用的温度依赖性产生影响。