Grain refinement in titanium prevents low temperature oxygen embrittlement.

Area of Science:

• Materials Science
• Metallurgy
• Mechanical Engineering

Background:

• Interstitial oxygen causes embrittlement in titanium alloys, especially at cryogenic temperatures.
• Stringent control of oxygen content is crucial for fabricating titanium and its alloys for low-temperature applications.

Purpose of the Study:

• To propose and evaluate a grain refinement strategy to mitigate oxygen embrittlement in titanium.
• To investigate the effect of ultrafine-grained (UFG) microstructure on the mechanical properties of Ti-O alloys at cryogenic temperatures.

Main Methods:

• Fabrication of titanium with controlled oxygen content (Ti-0.3wt.%O).
• Microstructural characterization to achieve ultrafine-grained (UFG) structures (~2.0 µm).
• Tensile testing at cryogenic temperatures (77 K) to evaluate strength and ductility.
• Analysis of grain boundary segregation and dislocation activities.

Main Results:

• Ultrafine-grained (UFG) Ti-0.3wt.%O exhibited an order of magnitude increase in uniform elongation compared to coarse-grained counterparts at 77 K.
• The UFG microstructure maintained ultrahigh yield strength.
• Strength-ductility synergy was attributed to diluted grain boundary oxygen segregation and enhanced dislocation activities.

Conclusions:

• Grain refinement is an effective strategy to overcome oxygen embrittlement in titanium alloys at cryogenic temperatures.
• The developed UFG Ti-O alloys offer potential for high-strength applications in low-temperature environments.
• This approach is applicable to other alloy systems suffering from interstitial embrittlement.