Effect of Directional Solidification on Microstructural Evolution and Properties of GH3625 Alloy

Area of Science:

• Materials Science
• Metallurgy
• Solidification Science

Background:

• Nickel-based superalloys like GH3625 are crucial for high-temperature applications.
• Precise microstructural control is key to optimizing GH3625 performance.
• Challenges exist in achieving desired microstructures and properties simultaneously.

Purpose of the Study:

• To investigate the influence of withdrawal rate on GH3625 microstructure.
• To evaluate the impact of withdrawal rate on mechanical and corrosion properties.
• To establish relationships between microstructure and properties for performance optimization.

Main Methods:

• Liquid-metal-cooled directional solidification system used.
• Microstructural analysis via Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS).
• Mechanical testing (uniaxial tensile) and electrochemical polarization tests conducted.

Main Results:

• Solid-liquid interface morphology transitions from cellular to dendritic with increasing withdrawal rate.
• Dendrite arm spacing significantly decreases with higher withdrawal rates.
• Optimal corrosion resistance and yield strength (409 MPa) achieved at 100 μm/s, with minimum Laves phase fraction.

Conclusions:

• Withdrawal rate is a critical parameter for controlling GH3625 microstructure and properties.
• Microstructural refinement through optimized solidification enhances strength and corrosion resistance.
• Study provides parameters for improved GH3625 performance in extreme environments.