基于LAPW算法磁记忆信号相变特性的研究

当应力达到临界屈服点时,铁磁性金属构件将产生塑性形变,造成重大的安全隐患。金属磁记忆检测技术可以快速、有效地检测出应力集中区域,但是,目前尚无有效的方法对临界屈服点处的磁记忆信号特征进行定量化分析。采用基于密度泛函理论的线性缀加平面波法(LAPW),建立了磁力学耦合模型,分析了临界屈服点的磁记忆信号特征,计算了弹性形变和塑性形变范围内,体系的差分电荷密度、原子磁矩、晶格结构随应力的变化关系。研究结果表明:随着应力的增加,固体中原子之间的结合力逐渐减弱,晶格结构的稳定性变差;当应力达到临界屈服点时,固体发生相变,磁记忆信号产生突变,磁记忆效应减弱。理论计算结果与实验结果具有很好的一致性。

Study on the characteristics of magnetic memory signal of phase transition point based on the LAPW algorithm

When the stress reaches to the critical yield point, the ferromagnetic metal component will produce the plastic deformation, which may further cause significant security risks. The metal magnetic memory testing technology can quickly and effectively diagnoses the stress concentration area, but there is still no effective method to quantitatively analyze the magnetic memory signal characteristics at the critical yield point. In this paper, we use the linear augmented plane wave method based on the density functional theory, to build the magnetic coupling model of magnetic memory firstly, then to analysis the quantitative characteristics of the magnetic memory signal at the critical yield point, and finally to calculate the variation relationships between different charge density, atomic magnetic moment, lattice structure and magnetic signal with stress under the situation of elastic deformation and plastic deformation. The experimental results show that with the increase of pressure, the binding force between atoms in the solid is gradually decreased, and the stability of crystal lattice structure is weakened; when the stress reaches to the critical yield point, the phase transition occurs in the solid, the mutation of magnetic memory signal appears, and the magnetic properties is suddenly weakened. Finally, the theoretical calculation results and the experimental results have a good consistence.