Structural properties and cyclic oxidation behavior of Ni-Al-Y superalloys

Abstract

The microstructure, microhardness, and oxidation resistance of ternary model Ni-13Al--2Y (at.%) and Ni-11Al-4Y (at.%) superalloys were studied in detail. The microstructures of alloys consisted of primary γ-Ni dendrites and residual eutectic. The Ni17Y2 intermetallic and γ-Ni were the major constituents of the eutectic phase mixture. The microhardness value of Ni-11Al-4Y alloy was higher than that of Ni-13Al-2Y alloy because of the higher amount of relatively harder eutectic. With increasing Y concentration from 2 to 4 at.%, the mass gain, oxide scale thickness, and oxidation rate remarkably increased. For both alloys, the oxide scale was comprised of three layers: NiO as a surface layer, Al2O3 as an inner layer in the metal/oxide interface, and mixed Al/Y oxides as an internal layer. Although the studied alloys exhibited fairly good scale adherence in conjunction with almost no important scale spallation, they exhibited faster oxidation kinetics along with higher mass gains.

Microstructural Evolution and Mechanical Properties of Y Added CoCrFeNi High-entropy Alloys Produced by Arc-melting

“…6. As can be seen, although there are some river lines and smooth facets indicating the appearance of transgranular fractures, the intergranular dominated fracture was observed in the HEA due to the formation of hard and brittle HS phase in the intergrain regions resulting in the weakness of the intergrain regions (27,46). In addition, the formation of tear edges in the fracture surface of the HEA shows relatively ductile behavior of the corresponding regions, which is consistent with what has been found in previous studies (32,47).…”

“…Because of their beneficial effects on molten steel purification and inclusion modification, additions of RE elements into steels have been a popular strategy for tailoring microstructure and improving mechanical performance (24)(25)(26). In addition, Y addition caused a substantial increase in the hardness of Fe-Al and Ni-Al-based superalloys (27,28).…”

Lattice Rotation Dependence on Microstructural Characteristics in a Low Carbon Steel

“…In both specimens, the most advantageous slip system was {110}<111>. Mehmet Sahin Atas et al [13][14][15] studied model Ni-15Al, Ni-Al-Y and Ni-Al-Nb superalloys and showed that aging time significantly influenced the size, shape and type of precipitates in these systems. They also studied these systems ex situ.…”

Effect of Nd Addition on the Microstructure and Cyclic Oxidation Behavior of NiAl–Cr(Mo) Eutectic Alloys

“…However, investigation of the surface scale morphologies does not indicate the entire oxidation process. Internal oxidation can occur under the surface scale[18,20]. Therefore, cross-sectional SEM-EDS analyses (Fig.13) are conducted.…”