研究了新近开发的一种定向凝固钴基高温合金DZ40M950℃长期时效后的组织与性能．结果表明，合金时效后室温强度提高，塑性降低980℃，83MPa持久性能提高，而816℃，215MPa持久性能下降．在时效过程中，初生碳化物M7C3和MC缓慢分解，细小的M23C6在基体中大量析出，M6C在一些M7C3表面生成．分析认为，合金性能变化主要归因于M(23)C6沉淀析出初生碳化物M7C3和MC分解，释放出碳原子，促进M(23)C6沉淀反应、M6C形成是由于钨的局部偏聚所致．
DZ40M, a newly developed directionally solidified Co-base superalloy was agedat 950℃ for long term. Its microstructural charateristics and mechanical properties at roomand elevated temperatures were studied. Long-term ageing results in substantial increase intensile strength and sharp reduction in ductility at room temperature. Its effect oil mechanicalprOPerties at elevated temperatures is dependent on eXperimental parameters. At 980℃ , 83 MPa,stress-rupture life is prolonged and at 816 ℃, 215 MPa, it is shortened. However, in all of thecases, the alloy possesses a high stress-rupture ductility. During ageing, primary carbide M7C3and MC decomposed sluggishly, fine M23C6 precipitated copiously around them and M6C formedon the surfaCe of some M7C3. Decomposition of the primary carbides promoted the precipitationof M23C6 by supplying carbon atoms and segregation of tungsten caused the precipitation ofM6C. It is thought that the change of mechanical properties of the alloy is attributed to theM23C6 precipitation.
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