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Process structure linkages for channel–die compressed mg alloy 08-10-2014
1. Steps to obtain 2-point statistics from
EBSD data using Binning
Team Members
Akash Gupta , Dipen Patel
Georgia Institute of Technology, Atlanta, US
2. Step 1: Extracting orientations from EBSD data
1 microstructure is selected at processing conditions: T=3000C, ɛ=73%, έ=0.01
OIM analysis software is used to extract 2-D pixel data containing crystal orientations (Φ1,Φ, Φ2) from .oim files
Size of microstructure = (200 x 200) μm , (1000 x 1000) pixels
Microstructure contains large number of grains with unique orientation leading to large number of local states ~ 105
¼ th microstructure (500 x 500) pixels was selected for further steps
3. Step 2: Finding equivalent orientation in FZ
12 lattice symmetry operations associated with hexagonal crystal lattice – leads to 12
equivalent orientations
Ref: Microstructure-sensitive Design for
Performance Optimization (2013), Authors: Brent L.
Adams, Surya Kalidindi, David T. Fullwood
4. Step 3: Binning of Fundamental Zone (FZ)
Number of local states in microstructure can be governed here
For this study we fixed number of local states (bins) to be 60 (5x4x3)
5. Step 4: Assigning bins to grains in microstructure
Based on orientations, each grain is assigned to one of the 60 bins (local states) in fundamental zone
Number of local states reduced from ~ 105 to 60
6. Step 5: 2-point statistics
Local state with highest frequency i.e. 54 is shown in white color in binary image
Auto-correlation for local state 54
7. Way Forward and Challenges
Compute all independent cross-correlations
Generate statistics for rest of the structures and do PCA
Challenges –
handling big data files and generating good images with 1000 x 1000 pixels
Repeating above mentioned process for rest of the structure files will require huge computational time