MEANS 2: Microstructure- and Micromechanism-Sensitive Property Models for Advanced Turbine Disk and Blade Systems
Final rept. 15 Feb 2005-31 Dec 2009
OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS
Pagination or Media Count:
This effort has focused on verification and refinement of the mechanism transitions at intermediate temperatures in the disk alloy Rene 104, with the observation of microtwinning, continuous faulting and dislocation by-pass at successively higher temperatures above 650 C. Evidence for the twin initiation process has also been obtained via TEM studies of specimens interrupted after small strain levels. A preliminary model for the novel microtwinning regime has been developed that appears to provide reasonable agreement with the present experimental creep response for Rene 104 and Rene 88. Modeling at the ab initio, atomistic and phase field levels is providing important insight into the activation parameters associated with the observed deformation mechanisms, augmented by insight from 3D atom probe measurements on y and y composition and ordering. Single crystals of Rene 104 have successfully been grown, and a limited number of microtensile compression as a function of crystal orientation whave been performed. A novel phase field model of directional coarsening rafting during high temperature, low stress creep of blade alloys has been developed. This model accounts for the local stress fields associated with matrix dislocations as well as the lattice misfit, and demonstrates promising qualitative agreement with experiment.
- Properties of Metals and Alloys