DD6单晶高温合金氧化物夹杂形成的热力学计算及分析

摘要

Calculation and analysis on the thermodynamics conditions for the formation of oxide inclusion during the vacuum induction melting of Ni-based single crystal superalloy DD6 have been carried out by using Thermo-calc thermodynamics software and JMatPro analysis software.The results show that the main oxide inclusion is Al2O3.Under the thermodynamic equilibrium state,the value of oxygen activity during the melting and solidification stages is within (3.21-14.0) × 10-7 and (1.63-4.89) × 10-8.It will cause increasing oxygen in the molten liquid and the formation of Al2O3 inclusion by using CaO crucible when the vacuum level is 0.1Pa.In order to make the content of Al2O3 inclusion reduce to less than 10 × 10-6,it is necessary to control oxygen content below 4.709 × 10-6 before alloying treatment.%采用Thermo-calc热力学计算软件以及JMatPro分析软件对DD6镍基单晶高温合金真空感应熔炼过程中氧化物夹杂形成的热力学条件进行了计算分析.结果表明:DD6单晶高温合金熔化和凝固过程中形成的氧化物夹杂主要为Al2O3.热力学平衡状态下,熔化阶段和凝固阶段合金液中氧的活度分别在(3.21～14.0)×10-7,(1.63～4.89)×10-8 范围内.在真空度为0.1Pa时,采用CaO坩埚熔炼DD6合金将会造成熔体增氧和Al2O3夹杂的产生.为了使Al2O3夹杂含量降低至10×10-6以下,合金化开始前应将氧的含量控制在4.709×10-6以内.