Development of local plasticity around voids during tensile deformation

A Study of the Internal Deformation Fields and the Related Microstructure Evolution during Thermal Fatigue Tests of a Single-Crystal Ni-Base Superalloy

“…The crystallographic feature of the cracks can be identified by the combination of slip trace and locally resolved shear stress analysis. This method has been applied to the analysis of void growth [ 37 ] and is especially useful for thermal fatigue analysis where the external loading is absent and traditional Schmid factor analysis is not applicable. The stress field demonstrated above needs to be interpreted with care.…”

“…These stresses are the residual stresses measured after thermal fatigue testing. It has been shown that the stress fields can be quite different during mechanical holding and after unloading [ 37 , 38 ], involving stress relief and/or local reversal of the directions of stresses. Nevertheless, the stress profiles shown in Figure 5 provide an idea of the size of the thermally affected zone, which may be useful for assisting engineering design.…”

Void Nucleation and Growth from Heterophases and the Exploitation of New Toughening Mechanisms in Metals

“…Figure 4 demonstrates a few distinct dislocation activities that form around the voids. Note that the voids in the copper (Figure 4a) developed a relatively homogeneous pattern of slip traces in comparison to those in the Ni superalloy (Figure 4b), resulting in a significantly faster void growth rate [25]. In contrast, no obvious slip traces were found around the voids in the titanium (Figure 2c), but rather very fragmented grain structures, which may form due to dislocation entanglement near the void surface.…”

“…This is evidenced by the two near vertical slip traces located at the top of the void, which tend to "pull-up" the upper part of the void into an elongated shape. This phenomenon implicitly correlates with a void growth mechanism by the gliding of a pair of anti-parallel dislocations [25]. The evolution of mesoscale dislocation structures was studied in situ under an SEM combined with elastic strain measurements using HR-EBSD [25].…”

“…Xu et al [20] analysed strain vs. void growth rate data from the literature and found that, under identical strain and stress triaxiality conditions, different alloys exhibited vastly different void growth rates, indicating that material-specific calibrations may be required for phenomenological models and that, in addition to stress triaxiality, the crystal plasticity of the matrix influences the evolution of the voids. On the other hand, recent molecular and dislocation dynamics simulations have provided valuable insights into the physical process of void growth under multiaxial loading conditions [21][22][23][24] and drawn forth several dislocation mechanisms [25] that may support mass transfer during void growth [26][27][28][29].…”