Preferred orientation relationships at the Cu/α−Al2O3 interface: Identification and theoretical explanation

Electron backscatter diffraction studies of copper matrix composites reinforced with sapphire particles and of Cu/α−Al2O3 heterostructures obtained by the pulsed laser deposition reveal a series of misorientations with high frequencies. Two of identified orientation relationships are well known in the literature and are treated as basic ones. The other misorientations are revealed for the first time. They differ from the basic ones by small Cu crystal rotations. According to the theoretical analysis, such a behavior enables a significant reduction of the interface energy. The manufacture conditions of composites limit the possibility of Cu crystal rotations. Therefore, one of the most energetically favorable orientation relationships (−4 4 3)[1 1 0]Cu‖(0 0 0 1)[0 1 −1 0] α−Al2O3 appears with a lower frequency. The obtained results indicate the necessity of the change in present manufacture methods. The appropriately selected conditions would enable formation of composites with stronger bondings at interphase boundaries.