Abstract The deformation and fracture processes of the Nd-Fe-B magnets during dynamic Brazilian tests were investigated using a split Hopkinson pressure bar (SHPB) with a high-speed photography (HSP) and digital image correlation (DIC). The load and work applied to the specimens were determined with the strain signals of incident, reflected and transmitted wave of the SHPB tests. It was revealed with HSP and DIC that at a load time before the maximal load, some cracks along the loaded diameter on the specimen surface became visible. The localized fracture strains at representable points of the failed area were given by DIC. The tensile strength of the specimens was obtained based on the elasticity theory when the load reached the maximum. The widths of the failed area on the specimen surface at the maximal load were determined with DIC. Furthermore, the fracture work applied to the specimen per failed volume which corresponds to the maximal load was given and could be an energy criterion for the fracture of the Nd-Fe-B specimens. It was indicated that the tensile strength and fracture work of the Nd-Fe-B magnets increase with the increase of strain rate in the Brazilian tests. It was shown that the transgranular fracture became visible in the recovered specimens for the higher strain rate tests.

中文翻译：

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动态巴西试验中烧结钕铁硼磁体断裂过程的实验研究

摘要 使用分裂式霍普金森压力棒 (SHPB) 和高速摄影 (HSP) 和数字图像相关 (DIC) 研究了 Nd-Fe-B 磁体在动态巴西试验期间的变形和断裂过程。施加到试样上的载荷和功由 SHPB 试验的入射波、反射波和透射波的应变信号确定。HSP 和 DIC 表明，在最大载荷之前的加载时间，试样表面沿加载直径的一些裂纹变得可见。失效区域可表示点处的局部断裂应变由 DIC 给出。当载荷达到最大值时，根据弹性理论得到试件的抗拉强度。最大载荷下试样表面失效区域的宽度用 DIC 确定。此外，给出了对应于最大载荷的每失效体积应用于试样的断裂功，并且可以作为 Nd-Fe-B 试样断裂的能量标准。巴西试验表明，随着应变速率的增加，Nd-Fe-B 磁体的抗拉强度和断裂功增加。结果表明，在较高应变率试验中，在恢复的试样中可以看到穿晶断裂。