Stacking Faults in θ' Precipitate of Al-Cu Alloy

Lattice defects in θ' precipitate of Al-Cu alloy have been studied by electron microscopy. The fine striations are observed in the as-aged precipitates, which have so far been believed to be found only in the specimens subjected to plastic deformation. It is concluded that these striations in the electron microscope image are due to stacking faults on {101} θ' plane. A possible displacement vector of the stacking faults is suggested to be 1/12 . It is considered that these stacking faults are produced in the θ' precipitates during aging. The stacking fault density is different from precipitate to precipitate.