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2nd World Congress on Integrated Computational Materials Engineering, Part II: Process Optimization: Multi-Objective Optimization of Microstructure in Wrought Magnesium Alloys.

Book ·
 [1];  [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

The microstructural features that govern the mechanical properties of wrought magnesium alloys include grain size, crystallographic texture, and twinning. Several processes based on shear deformation have been developed that promote grain refinement, weakening of the basal texture, as well as the shift of the peak intensity away from the center of the basal pole figure — features that promote room temperature ductility in Mg alloys. At ORNL, we are currently exploring the concept of introducing nano-twins within sub-micron grains as a possible mechanism for simultaneously improving strength and ductility by exploiting a potential dislocation glide along the twin-matrix interface — a mechanism that was originally proposed for face-centered cubic materials. Specifically, we have developed an integrated modeling and optimization framework in order to identify the combinations of grain size, texture and twin spacing that can maximize strength-ductility combinations. A micromechanical model that relates microstructure to material strength is coupled with a failure model that relates ductility to a critical shear strain and a critical hydrostatic stress. The micro-mechanical model is combined with an optimization tool based on genetic algorithm. A multi-objective optimization technique is used to explore the strength-ductility space in a systematic fashion and identify optimum combinations of the microstructural parameters that will simultaneously maximize the strength-ductility in the alloy.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Oak Ridge Leadership Computing Facility
Sponsoring Organization:
USDOE Office of Science; USDOE
OSTI ID:
1567500
Country of Publication:
United States
Language:
English

References (6)

Three-dimensional model of strength and ductility of polycrystalline copper containing nanoscale twins journal October 2008
Deformation twinning in a nanocrystalline hcp Mg alloy journal February 2011
Deformation behavior of ultrafine-grain (UFG) AZ31B Mg alloy at room temperature journal November 2006
Deformation mechanisms in Mg alloys and the challenge of extending room-temperature plasticity journal August 2009
The origin of “rare earth” texture development in extruded Mg-based alloys and its effect on tensile ductility journal November 2008
Strengthening Materials by Engineering Coherent Internal Boundaries at the Nanoscale journal April 2009

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