对定向凝固合金产生的热裂纹和裂纹断面进行了电子扫描分析。发现裂纹中间，尤其是裂纹尖端有晶间搭桥的存在，而在裂纹断面有晶间搭桥破断的痕迹。证明了以往热裂研究中提出的合金凝固后期存在晶间搭桥的设想，说明热裂纹的形成是由晶间搭桥破断而造成 Electron scanning analysis was conducted on the hot crack and the cracked section produced by the directional solidification alloy. Found in the middle of the crack, especially the existence of intercrystalline bridge at the tip of the crack, and in the crack cross-section there is traces of intergranular bridge break. This paper proves the assumption of intergranular bridging in the late stage of alloy solidification proposed in the previous hot cracking research, which shows that the formation of hot cracking is caused by the breakage of intergranular bridge