Prediction of interfacial phase formation and mechanical properties of Ti6Al4V–Ti43Al9V laminate composites

Ti6Al4V–Ti43Al9V laminate composites were successfully fabricated by hot-pack rolling using as-forged Ti43Al9V alloy and as-rolled Ti6Al4V alloy. The microstructure evolution of composites was investigated by electron probe microanalysis (EPMA) equipped with energy dispersive X-ray spectrometry (EDS) and the electron back scattered diffraction (EBSD). In order to better control the properties of laminate composites, two models are established for better control the thickness and phase formation of interfacial region, respectively. The mechanical properties of composites show a negative correlation with rolling temperature. The composite fabricated at 1125 °C exhibits the highest tensile strength 805 MPa and fracture toughness 49.2 MPa•m^1/2 which are much higher than Ti43Al9V alloy and other Ti–Al based laminate composites. The fracture features reveal that the increase of tensile strength is attributed to high density of dislocations and sub-structures stored in TiAl alloy and the crack propagation features show that the enhancement of toughness is associated with the aggravation of misorientation of α₂ phase and the increase of the amount of γ/B2 boundaries.