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Title: Interfacial dislocation motion and interactions in single-crystal superalloys

The early stage of high-temperature low-stress creep in single-crystal superalloys is characterized by the rapid development of interfacial dislocation networks. Although interfacial motion and dynamic recovery of these dislocation networks have long been expected to control the subsequent creep behavior, direct observation and hence in-depth understanding of such processes has not been achieved. Incorporating recent developments of discrete dislocation dynamics models, we simulate interfacial dislocation motion in the channel structures of single-crystal superalloys, and investigate how interfacial dislocation motion and dynamic recovery are affected by interfacial dislocation interactions and lattice misfit. Different types of dislocation interactions are considered: self, collinear, coplanar, Lomer junction, glissile junction, and Hirth junction. The simulation results show that strong dynamic recovery occurs due to the short-range reactions of collinear annihilation and Lomer junction formation. The misfit stress is found to induce and accelerate dynamic recovery of interfacial dislocation networks involving self-interaction and Hirth junction formation, but slow down the steady interfacial motion of coplanar and glissile junction forming dislocation networks. The insights gained from these simulations on high-temperature low-stress creep of single-crystal superalloys are also discussed.
Authors:
 [1] ;  [2] ;  [2] ;  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Max Planck Inst. fur Eisenforshung. Dusseldorf (Germany)
Publication Date:
OSTI Identifier:
1165777
DOE Contract Number:
DE-AC52-07NA27344
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Materialia; Journal Volume: 79; Journal Issue: C
Publisher:
Elsevier
Research Org:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 97 MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE DISLOCATION DYNAMICS; SUPERALLOYS; HIGH-TEMPERATURE LOW-STRESS CREEP; INTERFACIAL DISLOCATION MOTION; DISLOCATION INTERACTIONS