The development of residual stresses in Ti6Al4V-Al3Ti metal-intermetallic laminate (MIL) composites

Residual stresses in the metal (Ti6Al4V)-intermetallic (Al3Ti) laminate composite are generated when cooled from the processing temperature (∼700 °C) to ambient temperature, because of the difference in thermal expansion coefficients between Ti6Al4V and Al3Ti. Two stress release mechanisms, creep and crack propagation, are proposed to explain the development of residual stress during cooling process. Both analytical calculations and finite element simulations are performed. In the analytical modeling, a critical stress criterion is proposed in order to determine the initiation of crack propagation. In the finite element simulation, the J-integral is used as a criterion for crack evolution; it enables the establishment of the distribution of the residual stress as a function of temperature. The results of both analytical modeling and finite element simulation show good agreement with the experimental results obtained through X-ray diffraction.