一、前言定向凝固高温合金的研究在我国已有十多年的历史,七十年代末期,该项技术在航空发动机上经受了考验。随着发动机涡轮前温度日益提高,已经广泛地采用冷却技术,为此,定向凝固高温材料使用的主要对象是复杂的空心叶片。薄壁空心定向涡轮叶片就是其中一例。1981年 DZ3合金浇注零件时,在薄壁处沿晶出现严重裂纹,研究和改进材料的可铸性成了当务之急。因此,研究裂纹的性质、形成以及影响因素,从而寻求克服的途径,成了定向 I. Introduction Directional solidification superalloy research in our country has been more than 10 years of history, the late seventies, the technology has been tested on the aero-engine. With the increasing temperature of the turbine before the engine, cooling technology has been widely used, therefore, the main target of the directional solidification of high temperature materials is a complex hollow blade. Thin-walled hollow directional turbine blades is one example. 1981 DZ3 alloy pouring parts, along the thin wall at the crystal serious cracks, research and improve the material castability has become a top priority. Therefore, the study of the nature of cracks, the formation and influencing factors, and thus seek ways to overcome, has become a target