In-Situ SEM Observation on Fracture Behavior of Titanium Alloys with Different Slow-Diffusing β Stabilizing Elements

Area of Science:

• Materials Science
• Metallurgy
• Physical Chemistry

Background:

• Titanium-aluminum alloys are critical for high-temperature applications.
• Understanding fracture behavior in these alloys is essential for performance optimization.
• The role of slow-diffusing beta stabilizing elements (Mo, W) in Ti-Al-Sn-Zr-Mo-Nb-W-Si alloys requires detailed investigation.

Purpose of the Study:

• To investigate the fracture behaviors of two Ti-Al-Sn-Zr-Mo-Nb-W-Si alloys with varying Mo and W content.
• To elucidate the influence of slow-diffusing beta stabilizing elements on high-temperature mechanical properties.
• To understand the mechanisms of microvoid initiation and growth during tensile deformation.

Main Methods:

• In-situ tensile testing at 650 °C.
• Scanning electron microscopy (SEM) for microstructural analysis.
• Three-dimensional atom probe (3DAP) for elemental distribution analysis.

Main Results:

• Mo and W primarily dissolve in the beta phase and cluster near alpha/beta interfaces.
• Increased Mo and W content enhances ultimate tensile strength and elongation at 650 °C.
• Microvoids initiate at alpha/beta interfaces; increased beta phase content and decreased phase size inhibit nucleation and growth.

Conclusions:

• Higher concentrations of slow-diffusing beta stabilizing elements (Mo, W) improve high-temperature strength and plasticity.
• The segregation of Mo and W at alpha/beta interfaces reduces diffusion coefficients and inhibits microvoid growth.
• Optimizing Mo and W content is crucial for enhancing the fracture resistance of these titanium alloys.