Influence of Y-Rich Compounds on High-Cycle Fatigue Performance of Y-Doped M951 Superalloy

• Published in: Journal of materials engineering and performance 2019-10, Vol.28 (10), p.6053-6062
• Main Authors: Zhou, Pengjie, Song, Dehang, Liu, Ning, Ueshima, Nobufumi, Oikawa, Katsunari
• Format: Article
• Language: English
• Subjects: BCC LATTICES; Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; CRACK PROPAGATION; DOPED MATERIALS; Engineering Design; HEAT RESISTING ALLOYS; MATERIALS SCIENCE; Quality Control; Reliability; S-N DIAGRAM; Safety and Risk; Tribology; YTTRIUM ALLOYS
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-019-04383-7

The performance of Y-doped M951 superalloy under high-cycle fatigue was investigated experimentally to determine the effect of Y-rich compounds on this behavior. The selected testing temperatures were 700 and 900 °C, and the stress ratio was R  = 0.1. The fatigue life was shown to decrease as the stress amplitude increased, according to a typical Whöler S-N diagram. Two types of crack initiation sites were observed on the fractured surfaces: microshrinkage clusters and Y-rich compounds. Analysis by TEM indicated that the Y-rich compounds consisted of Al 2 Ni 6 Y 3 particles with BCC structure and Ni 5 Y particles with hexagonal structure. Cracks had initiated and propagated along the interface between Al 2 Ni 6 Y 3 phase and the matrix. These Y-rich compounds varied considerably in size, from 1 to 769 μm, and the large-size Y-rich compounds were shown to be the preferred site for fatigue crack origin. The ability of Y in the removal of sulfur was considered. And the small-size Y-S product from the reaction between Y and S was shown to exhibit no deleterious effect on the fatigue property of the M951 Ni-based superalloy.