Experimental Study of As-Cast and Heat-Treated Single-Crystal Ni-Based Superalloy Interface Using TEM

Area of Science:

• Materials Science
• Metallurgy
• Nanotechnology

Background:

• The interface structure critically influences the strength and toughness of multiphase systems.
• Accurate characterization of the interface in single crystal (SX) Ni-based superalloys is essential for performance.
• Understanding the nanoscale interface is key to developing advanced superalloys.

Purpose of the Study:

• To measure the γ and γ' lattice constants and interface width in dendritic and interdendritic regions of cast and heat-treated SX Ni-based superalloys.
• To investigate the correlation between interface width and lattice mismatch (γ/γ' misfit).
• To elucidate the effects of heat treatment on the microstructure and properties of SX Ni-based superalloys.

Main Methods:

• Utilized advanced equipment for nanoscale characterization of the γ/γ' interface.
• Measured lattice constants and interface widths in both as-cast and solution-treated samples.
• Analyzed microstructural differences between dendritic and interdendritic regions.

Main Results:

• Interface width was larger in the dendritic region than the interdendritic region for as-cast samples.
• A positive correlation was observed between interface width and the absolute value of lattice misfit.
• Heat treatment increased interface width, decreased misfit, increased γ lattice constant, and decreased γ' lattice constant.

Conclusions:

• Property heat treatment significantly increases lattice constants of γ and γ' phases.
• Heat treatment reduces lattice mismatch at the two-phase interface, improving high-temperature stability.
• Improved understanding of Ni-based single crystal superalloy microstructure will guide future alloy design.