Characterization of γ′ precipitate and γ/γ′ interface in polycrystalline Ni3Al-based superalloys.

The microstructure, element segregation and γ/γ′ interface characters of polycrystalline Ni 3 Al-based superalloys under conventionally solidified (~10 K/s) and rapidly solidified (~103 K/s) conditions were investigated. Cr and Fe are primarily partitioned into the γ phase while Al and Ni are into γ′ phase. However, rapid solidification rate of spray casting alloy improves the solubility of Cr and Fe elements at the expense of Al in γ′ phase, which decreases the lattice parameters of γ and γ′ phases. Moreover, it further increases the absolute value of γ/γ′ lattice misfit and contributes to the formation of (100) plane misfit dislocations in γ/γ′ interface. As a result, spray casting specimen possesses higher hardness (6.5 ± 1.0 GPa) and elastic moduli (166.4 ± 15.9 GPa) than that in as-cast alloy with lower solidification rate. • Rapid solidification rate of spray casting alloy improves the solubility of Cr and Fe elements in γ′ phase. • It further increases the absolute value of γ/γ′ lattice misfit. • The rapidly solidified spray casting alloy possesses high hardness and elastic moduli. [ABSTRACT FROM AUTHOR]