Massive interstitial solid solution alloys achieve near-theoretical strength.

Area of Science:

• Materials Science
• Metallurgy
• Solid-State Chemistry

Background:

• Interstitial elements (C, N, O) strengthen metals by distorting lattices.
• High interstitial concentrations typically form brittle ceramics, limiting solid solution strengthening.
• Existing methods struggle to incorporate substantial interstitial content into metallic alloys.

Purpose of the Study:

• To introduce a new class of alloys: massive interstitial solid solution (MISS) alloys.
• To demonstrate the possibility of achieving high interstitial concentrations without ceramic phase formation.
• To develop metallic materials with enhanced mechanical properties.

Main Methods:

• Utilizing a highly distorted substitutional host lattice to accommodate interstitials.
• Developing a TiNbZr-O-C-N model system to test the MISS concept.
• Characterizing the alloy's microstructure and mechanical properties under compression.

Main Results:

• Achieved a massive interstitial solid solution with 12 at.% oxygen in the TiNbZr-O-C-N system.
• Observed no formation of ceramic phases (e.g., oxides) despite high oxygen content.
• Demonstrated an ultrahigh compressive yield strength of 4.2 GPa and 65% strain at room temperature.

Conclusions:

• The MISS concept enables the incorporation of large amounts of interstitial elements into metallic alloys.
• This approach overcomes the ceramic phase limitation, paving the way for new high-performance materials.
• MISS alloys offer a promising new avenue for developing advanced metallic materials with superior strength and ductility.