Dislocation-climb-mediated void evolution in creeping metallic crystals

Creep void evolution is a key damage process in high-temperature alloys, because void growth, shape change, and coalescence promote damage localization and thereby accelerate the transition to tertiary creep and eventual rupture. Existing studies based on single-void unit cells have clarified the effects of stress state, crystallographic orientation, and void geometry on creep void evolution, but have paid little attention to how void behavior is changed by the underlying creep deformation mechanism itself, especially dislocation climb. Here, this issue is addressed using a finite-strain crystal-plasticity finite-element framework with crystallographic slip and dislocation climb. A three-dimensional periodic single-crystal unit cell containing a pre-existing intragranular spherical void is analyzed under multiaxial loading, and a climb-enabled constitutive description calibrated for the high-temperature IN617 alloy is systematically compared with a matched slip-only reference over prescribed stress-triaxiality and Lode-parameter combinations and crystallographic orientations. Within the adopted periodic single-void unit-cell and constitutive framework, the results show that admitting climb produces a distinct creep-void response rather than merely accelerating the overall deformation. In particular, climb strengthens the net tendency toward void growth, causes the coalescence criterion to be reached over a wider stress-state range within the early 𝐸 e q ≤ 1 observation window, weakens collapse at low triaxiality, and makes stress triaxiality a more dominant control of the global cell-averaged creep response while reducing that response’s sensitivity to the Lode parameter and crystallographic orientation. These trends are interpreted in terms of two model-internal features of climb: an admissible non-zero plastic volumetric contribution and an explicit hydrostatic-stress contribution to the microscopic driving force. Overall, the study reveals a distinct micromechanical pathway for creep void evolution when climb becomes active and provides a basis for future analyses based on single-void unit cells and creep-damage models that account for mechanism-dependent void evolution.