对某型号发动机单晶涡轮叶片进行X射线检测时，底片上有疑似外来物的缺陷显示。为了确定该外来物的形成原因，对叶片进行了剖切，对外来物取样进行能谱分析，发现该外来物与叶片基体元素含量没有明显差异。结果表明，该外来物是磨加工过程中产生的金属粉末通过叶片上的进排气孔进入叶片型腔内，在进行"叶冠装配面钎焊"工序时，在真空钎焊炉的高温环境下紧紧地黏接在叶片内壁形成的。

When X-ray test was performed on the single crystal turbine blades of a certain type engine, there is an indication of suspected foreign objects on the film. In order to find out the cause of foreign objects, we cut a blade and through energy spectrum analysis we found that there was no significant difference on material element content between foreign objects and the blade. It was indicated that the metal-powder produced in the grinding process entered the blade cavity through the inlet and exhaust holes in the blade, and during brazing of the leaf crown assembly surface, the powders were bonded to the inner wall of the blade in the vacuum brazing furnace at high temperature.