Creep properties of single crystal Ni-base superalloys (SX): A comparison between conventionally cast and additive manufactured CMSX-4 materials

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 762; p. 138098
• Main Authors: Bürger, D., Parsa, A.B., Ramsperger, M., Körner, C., Eggeler, G.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05-08-2019; Elsevier BV
• Subjects: Additive manufactured single crystal; Bridgman method; Creep; Creep tests; Crystal growth; Directional solidification; Directionally solidified single crystals; Electron beam melting; Heat treating; Heat treatment; High temperature; Microstructure; Ni-base single crystal superalloys; Nickel base alloys; Precipitates; Properties (attributes); Single crystals; Superalloys; Tensile creep; Directionally solidified single crystals; Ni-base single crystal superalloys; Creep; Additive manufactured single crystal; Microstructure
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2019.138098

The present work compares the microstructures and the creep properties of two types of single crystal Ni-base superalloy CMSX-4 materials (SXs). One was produced by conventional directional solidification Bridgman processing. The other was manufactured by selective electron beam melting (SEBM). The microstructures of the two types of materials are compared with emphasis placed on the large (dendritic/interdendritic regions) and small scale (γ-matrix/γ′-precipitates) microstructural heterogeneities, which characterize SX microstructures and their evolution during processing, heat treatment and creep. It is shown that heat treated SEBM materials have creep properties, which match or even outperform those of conventionally processed SX materials. Creep properties were assessed using a miniature creep test technique where [001] miniature tensile creep specimens were tested in the high temperature/low stress (1050 °C, 160 MPa) and in the low temperature/high stress (850 °C, 600 MPa) creep regimes. The creep behavior is interpreted based on microstructural results, which were obtained using analytical scanning and transmission electron microscopy (SEM and TEM).