Determination of the Young Modulus of Ti-TiAl₃ Metallic Intermetallic Laminate Composites by Nano-Indentation

Nano-indentation is an important technique to determine the Young modulus of multiphase materials where normal tensile tests are not appropriate. In this work, Ti-TiAl₃ metallic-intermetallic laminate composites have been fabricated successfully in open atmosphere using commercial purity Al and Ti foils with 250 μm and 500 μm initial thicknesses, respectively. Sintering process was performed at 700°C under 2 MPa pressure for 7.5 h. Mechanical properties including the Young modulus were determined after manufacturing. The Young moduli of metallic and intermetallic phases were determined as 89 GPa and 140 GPa, respectively. Microstructure analyses showed that aluminum foil was almost consumed by forming a titanium aluminide intermetallic compound. Titanium aluminides grow up through spherical shaped islands and metallic-intermetallic interface is a wavy form in Ti-Al system. Thus, the final microstructure consists of alternating layers of intermetallic compound and unreacted Ti metal. Microstructure and phase characterizations were performed by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Hardness of test samples was determined as 600 HV for intermetallic zone and 130 HV for metallic zone by the Vickers indentation method.