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为了分析高温合金DD483铸造叶片单晶率很低的原因,对该合金凝固过程中的过冷能力进行了测量。为了保证温度测量的可靠性,采用两种测温系统和两种热电偶丝。通过测得大量合金熔点和形核温度数据,得出平均形核过冷度作为该合金的过冷能力。从测量结果看,不论用哪种热电偶丝(国产或国外产)和哪种测温系统(固定式或移动式)该合金的过冷能力都是大约9.3℃,远远低于其他高温合金。证明这种合金在所用的型壳中抗杂晶能力很弱,因而具有较差的单晶铸造性能。
In order to analyze the reasons for the low single crystal rate of the as-cast DD483 superalloy, the overcooling capability of the alloy during solidification was measured. In order to ensure the reliability of temperature measurement, using two temperature measurement systems and two thermocouple wire. By measuring a large number of alloy melting point and nucleation temperature data, the average nucleation undercooling was obtained as the supercooling capacity of the alloy. From the measurement results, no matter what kind of thermocouple wire (domestic or foreign) and temperature measurement system (fixed or mobile) the alloy’s supercooling capacity is about 9.3 ℃, far lower than other high-temperature alloys . It has been demonstrated that this type of alloy has weak resistance to miscrystallization in the used shell and thus has poor single crystal casting properties.