The morphology and structure of microcracks extending toward B₄C were investigated from a joint obtained by sandwiching Al foil between two B₄C ceramic plates and heat-treating at 1000 °C in vacuum. Network-like structures of cracks were seen, and Al penetrated the extremely narrow part at the tip. The molten Al penetrated a narrow area within the cracks and filled them. Several compounds were produced in the primary junction area because of reactions between Al and B₄C. However, only pure Al was present within the cracks. Atoms moved easily in a wide joint interface, and a reaction occurred accordingly, whereas in a narrow region inside the micro crack, atoms moved with difficulty even if molten Al penetrated the crack. The fact that the reaction is unlikely to occur inside the crack is consistent with the permeation of Al into the inside of the elongated crack.

通过将铝箔夹在两块 B ₄ C 陶瓷板之间并在 1000 °C 下真空热处理获得的接头，研究了向 B ₄ C延伸的微裂纹的形态和结构。可以看到裂纹的网状结构，Al 穿透了尖端极窄的部分。熔融铝渗入裂纹内的狭窄区域并填充它们。由于 Al 和 B ₄之间的反应，在初级连接区产生了几种化合物C. 然而，裂纹中只存在纯铝。原子在较宽的接合界面内容易移动，并相应地发生反应，而在微裂纹内部的狭窄区域内，即使熔融铝穿透裂纹，原子也难以移动。裂纹内部不太可能发生反应这一事实与Al渗透到细长裂纹内部是一致的。