Effect of residual stresses on the mechanical properties of Ti-TiAl laminate composites fabricated by hot-pack rolling

The Ti-TiAl laminate composites with different titanium alloy volume fraction were successfully designed and fabricated by hot-pack rolling. Due to the mismatch of coefficient of thermal expansion (CTE), the composites show pronounced residual stresses. The TiAl alloy possesses residual tensile stress while the titanium alloy possesses residual compressive stress. With the increase of titanium alloy volume fraction, the residual compressive stress is decreased but the residual tensile stress is opposite. The residual compressive stress is beneficial for improving the mechanical properties of Ti-TiAl laminate composites, which is because it enhances the strength and postpones the rupture of composites during tensile test. The higher residual compressive stress also improves the fracture toughness of composites by extending crack propagation. The composite with 42 vol% titanium alloy shows the optimal comprehensive mechanical properties, which is higher than most of other Ti-Al based metal-intermetallic laminate composites.