CALPHAD-guided interlayer design for crack-free additive manufacturing of copper C18150 - Inconel 625 bimetallic...

Area of Science:

• Materials Science
• Metallurgical Engineering
• Computational Materials Science

Background:

• Additive manufacturing (AM) of bimetallic structures (copper alloys and Ni-based superalloys) is vital for extreme environments.
• Interface cracking during AM fabrication is a significant challenge due to thermophysical property mismatches.

Purpose of the Study:

• To decode nonequilibrium solidification and phase stability using a CALPHAD-based ICME framework to predict cracking susceptibility in bimetallic systems.
• To identify strategies for mitigating interface cracking in AM of copper alloys and Ni-based superalloys.

Main Methods:

• Utilized a CALPHAD-based Integrated Computational Materials Engineering (ICME) framework.
• Investigated nonequilibrium solidification, phase stability, and liquid phase separation.
• Performed wire arc additive manufacturing (WAAM) experiments for validation.

Main Results:

• Liquid phase separation was identified as a dominant mechanism influencing solute redistribution and thermal stress.
• Crack-free interfaces between C18150 and In625 were achieved using intermediate layers with 65 wt.% In625.
• A quantitative correlation between phase separation and the cracking susceptibility coefficient (CSC) was established.

Conclusions:

• The study provides a method to analyze bimetallic systems prone to phase separation and cracking.
• ICME methodologies successfully linked thermochemical modeling with process optimization.
• New principles for designing defect-resistant bimetallic components for extreme environments, like rocket engine nozzles, were proposed.