Room Temperature Ductility of TiAl Alloys with Different Machined Surface Conditions

The standard tensile specimens of as-cast titanium aluminide alloy were prepared by using grinding and polishing as the final procedure. The surface quality and surface residual stress of the two specimens were comparatively analyzed. Tensile tests were taken at room temperature. The results show that the surface microstructure of the ground and polishing TiAl alloy was the same as that of the as-cast alloy, which was near lamellar microstructure. It decreased the surface roughness of the ground specimen from 0.5 μm to 0.22 μm by polishing. The wear scar guantity decreased, and its angle changed from acute angle to obtuse angle. The surface stress of both the two specimens was compressive residual stress, while that of the polished specimen was higher. The elongation at room temperature of the polished specimens was improved obviously, which was increased from 133% to 2.33%.