X-ray tomographic imaging of Ti/SiC composites

Area of Science:

• Materials Science
• Mechanical Engineering
• Composite Materials

Background:

• Titanium alloys reinforced with ceramic fibers are critical in aerospace and automotive applications.
• Understanding damage mechanisms in these composites is essential for predicting material performance and failure.
• Ti-6Al-4V/SCS6 SiC composites present complex microstructures that influence damage propagation.

Purpose of the Study:

• To investigate the occurrence and evolution of damage in Ti-6Al-4V/SCS6 SiC fibre composites.
• To analyze damage mechanisms at different scales, from single fibres to multi-ply structures.
• To characterize novel damage morphologies and their impact on composite integrity.

Main Methods:

• Application of high-resolution tomographic synchrotron X-ray imaging.
• In-situ mechanical testing of composite specimens under tensile load.
• Controlled introduction of damage via laser drilling in single-ply composites.
• Microstructural analysis of fibre fragmentation, wedge cracking, and matrix crack propagation.

Main Results:

• Observed progressive damage accumulation, including full fibre fragmentation in single fibre composites.
• Identified subsequent fibre wedge cracks nucleating from initial fracture damage.
• Documented spiral defects during failure in single-ply composites.
• Characterized matrix crack front features such as advancement in fibre-free regions and bifurcation near fibres in multi-ply composites.

Conclusions:

• High-resolution synchrotron X-ray imaging is effective in elucidating complex damage processes in Ti-6Al-4V/SCS6 composites.
• The study provides detailed insights into fibre fracture, secondary cracking, and matrix failure modes.
• Findings contribute to a better understanding of composite material behavior under stress, informing design and failure analysis.