Deformation features of a nickel-base superalloy single crystal during compression creep

The microstructure evolution of a single crystal nickel-base superalloy with [0 0 1] orientation during compressive creep at 1040 °C has been investigated by means of the observation of transmission electron microscopy. Results show that the cuboidal γ′ phase in the alloy is transformed into the strip-like rafted structure along the direction parallel to [0 0 1] stress axis during compressive creep. During the primary creep, the deformation feature of the alloy is the 1/2〈1 1 0〉 dislocations activated in the γ matrix. After crept for 50 h, the strip-like rafted γ′ (Ni3Al) phase in alloy is sheared by the 〈1 1 0〉 super-dislocations which may be dissociated into the 1/3〈1 1 2〉 super-Shockley dislocations. The SISF formed from the dissociation of the [1 0 1̄] super-dislocation is enclosed by the partials loops. One of the reason resulting in a smaller strain value of the alloy during compressive creep is the Giameis locks made from a combination of the partials loops and SISF which hinder the continuous expansion of the original [1 0 1̄] super-dislocation.