Oxygen-mediated high uniform plasticity in α-β titanium alloys

Area of Science:

• Materials Science
• Metallurgy
• Mechanical Engineering

Background:

• Titanium alloys face a critical trade-off between yield strength and uniform elongation.
• Oxygen typically embrittles titanium alloys, limiting their performance.

Purpose of the Study:

• To overcome the yield strength-uniform elongation trade-off in titanium alloys.
• To transform high oxygen content from a detrimental factor into a performance enhancer.

Main Methods:

• Utilized high oxygen content (≥0.40%) to activate pyramidal slip in the α-phase.
• Engineered a specific α-β microstructure using Ti-O-Fe alloy design.
• Employed laser-based powder bed fusion and annealing for microstructure control.

Main Results:

• Achieved record uniform elongations in high-strength α-β titanium alloys.
• Ti-0.45O-4Fe demonstrated ≥14% uniform elongation at ≥980 MPa yield strength.
• Ti-0.5O-5Fe achieved ≥13% uniform elongation at ≥1075 MPa yield strength.

Conclusions:

• Successfully addressed both the yield strength-uniform elongation trade-off and oxygen embrittlement.
• Demonstrated a novel design paradigm for advanced α-β titanium alloys.
• Highlighted the potential of oxygen as a performance-enhancing element in titanium alloys.