Rare-earth barium-copper-oxide (REBCO) superconductors are high-field superconductors fabricated in a tape geometry that can be utilized in magnet applications well in excess of 20 T. Due to the multilayer architecture of the tape, delamination is one cause of mechanical failure in REBCO tapes. During a mechanical slitting step in the manufacturing process, edge cracks can be introduced into the tape. These cracks are thought to be potential initiation sites for crack propagation in the tapes when subjected to stresses in the fabrication and operation of magnet systems. We sought to understand which layers were the mechanically weakest by locating the crack initiation layer and identifying the geometrical conditions of the slitter that promoted or suppressed crack formation. The described cracking was investigated by selectively etching and characterizing each layer with scanning electron microscopy, laser confocal microscopy, and digital image analysis. Our analysis showed that the average crack lengths in the REBCO, LaMnO₃ (LMO) and Al₂O₃ layers were 34 μm, 28 μm, and 15 μm, respectively. The total number of cracks measured in 30 mm of wire length was between 3000 and 5700 depending on the layer and their crack densities were 102 cracks mm⁻¹ for REBCO, 108 cracks mm⁻¹ for LMO, and 183 cracks mm⁻¹ for Al₂O₃. These results indicated that there are separate crack initiation mechanisms for the REBCO and the LMO layers, as detailed in the paper. With a better understanding of the crack growth behavior exhibited by REBCO tapes, the fabrication process can be improved to provide a more mechanically stable and cost-effective superconductor.

稀土钡铜氧化物 (REBCO) 超导体是以带状几何形状制造的高场超导体，可用于超过 20 T 的磁体应用。由于带的多层结构，分层是导致REBCO 磁带的机械故障。在制造过程中的机械切割步骤中，可能会在胶带中引入边缘裂纹。当在磁体系统的制造和操作中受到应力时，这些裂纹被认为是带中裂纹扩展的潜在起始点。我们试图通过定位裂纹起始层并确定促进或抑制裂纹形成的纵切机的几何条件来了解哪些层的机械性能最弱。通过选择性蚀刻和用扫描电子显微镜、激光共聚焦显微镜和数字图像分析表征每一层来研究所描述的裂纹。我们的分析表明，REBCO、LaMnO 中的平均裂纹长度₃（LMO）和Al ₂ ö ₃层分别为34 μ米，28 μ m和15 μ米，分别。裂纹在金属丝长度的30毫米测量的总数为3000和5700之间取决于层上和其抗裂密度分别为102层毫米的裂纹^-1为REBCO，108层的裂纹毫米^-1为LMO，和183米的裂缝毫米^-1为铝₂ O ₃. 这些结果表明 REBCO 和 LMO 层有不同的裂纹萌生机制，如论文中详述的那样。通过更好地了解 REBCO 带所表现出的裂纹扩展行为，可以改进制造工艺以提供更机械稳定和更具成本效益的超导体。