Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7982293 | Materials Science and Engineering: A | 2013 | 10 Pages |
Abstract
Creep and rafting in Ni-based single crystal René N4 is described using reported phenomenological models after modifying the creep model to represent the rafting induced hardening of the structure against creep and the greater propensity for shearing of γⲠas the structure rafts and dislocation density in the channels and γ/γⲠinterface builds up. The proposed model can describe the creep strain evolution at 1144 K over the stress range 241-413 MPa. The rafting model is shown to provide an adequate representation of horizontal and vertical channel width evolution at 1144 K and 1255 K. The variation of the physical parameters in the creep model viz., back stress, dislocation density and shear rate is rationalized scientifically thereby substantiating the physical basis of the model. The development of back stress in the channels is explained mechanistically through the deposition of dislocation segments at γ/γⲠinterface by the Orowan loops expanding in the channel and the recovery of the interfacial dislocation networks. The evolution in Orowan stress consequent to rafting and its effect on dislocation activity are elucidated. The evolution of the kinetics for dynamic and static recovery processes which accompany creep strain accumulation has also been explained mechanistically.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
C.Girish Shastry, V.Sivakumar G. Kelekanjeri, T. Vishwanath, Shamik Chaudhuri,