Thermodynamics-guided alloy and process design for additive manufacturing.

Area of Science:

• Materials Science
• Metallurgy
• Additive Manufacturing

Background:

• Conventional metal processing involves multiple steps like casting, deformation, and heat treatment.
• Additive manufacturing (AM) achieves desired properties in a single fabrication process, involving solidification and cyclic remelting.
• Thermodynamic and kinetic differences during AM can cause defects such as hot cracking.

Purpose of the Study:

• To investigate the thermodynamic and kinetic factors influencing hot cracking in additive manufacturing.
• To develop a knowledge-based approach for designing alloys resistant to hot cracking during AM.
• To demonstrate the application of this approach using IN738LC superalloy.

Main Methods:

• Analyzing the thermodynamic and kinetic responses of alloys to high cooling rates inherent in AM.
• Investigating constitutional undercooling, solidification intervals, and secondary phase precipitation.
• Modeling and experimental validation of alloy design strategies to mitigate hot cracking.

Main Results:

• Identified key thermodynamic and kinetic parameters leading to hot cracking in IN738LC superalloy.
• Developed and applied a tailored alloy design approach to successfully prevent hot cracking.
• Demonstrated the effectiveness of the approach in a commercially important superalloy.

Conclusions:

• Understanding the fundamental thermodynamic and kinetic principles is crucial for designing AM-suitable alloys.
• The presented approach offers a pathway to adapt other hot-cracking susceptible alloy systems for additive manufacturing.
• This research contributes to overcoming critical defects in AM, enabling wider application of the technology.