1. ORIENTATION IMAGING MICROSCOPY (OIM) - SOME CASE STUDIES
EML 5930 (27-750)
Advanced Characterization and Microstructural Analysis
A. D. Rollett, P.N Kalu, D. Waryoba
Spring 2006

2. OUTLINE REVIEW OF OIM CASE STUDIES
Development of Polishing Technique For OIM Study of Heavily Deformed OFHC Copper
Recrystallization in Heavily Deformed OFHC Copper
Heavily Deformed Cu-Ag
Deformed and Annealed OFHC Copper
Deformed and Annealed Cu-Nb
Other Examples

3. INTRODCUTION TO OIM - Diffraction
Diffraction of inelastically scattered electrons by lattice planes (hkl) according to Bragg’s law:
Sections of a pair of Kossel cones form a pair of parallel straight Kikuchi lines on the flat phosphor screen.
For maximum intensity, the specimen surface is steeply tilted at an angle of 20°-30° from grazing incidence.

4. INTRODCUTION TO OIM - EBSP formation

5. INTRODCUTION TO OIM - Data acquisition

6. TECHNIQUE DEVELOPMENT

7. TECHNIQUE DEVELOPMENT
EBSPs from a sample prepared by standard metallographic technique: Polished
(a) OIM grain boundary map and (b) EBSD patterns

8. TECHNIQUE DEVELOPMENT
EBSPs from a sample prepared by standard metallographic technique: Polished + etched
(a)
(b)
(a) OIM grain boundary map and (b) EBSD patterns

9. TECHNIQUE DEVELOPMENT
EBSPs from a sample prepared by Novel technique - Polished + Etched + Polished
(a)
(b)
(a) OIM grain boundary map and (b) EBSD patterns

10. Image Quality
Confidence Index
Image Quality
Confidence Index

11. TECHNIQUE DEVELOPMENT
IPF of wire drawn OFHC copper deformed to  = 3.2, obtained via (a) OIM and (b) X-ray diffraction techniques
CONCLUSIONS
Polishing by the novel technique, which consists of polishing+etching+polishing, produced high quality EBSPs leading to excellent OIM image.
IPF from OIM were consistent with the IPF from X-ray diffraction

12. Rex in HEAVILY DEFORMED OFHC COPPER

13. Rex in HEAVILY DEFORMED OFHC COPPER
Microstructure
Optical micrograph showing microstructure after deformation to  = 1.3,  = 392 MPa. No recrystallization
Optical micrograph showing microstructure after deformation to  = 3.2,  = 405 MPa. Arrows show pockets of recrystallized grains.

14. Rex in HEAVILY DEFORMED OFHC COPPERU X V Y W DD
(b)
(a)
OIM map showing grain orientations at (a) p = 2.3, UTS = MPa, and (b) p = 3.2, UTS = 405 MPa. The lines represent high angle boundaries, with misorientation > 15o.

15. Rex in HEAVILY DEFORMED OFHC COPPER

16. <112>54°
{-265}< –7>
<213>75°
{ }<-65-2>
<-4-13>45°
{ }<7 29 2> 1
<313>85°
{184}< >
<12-6>40°
{-4-19}<-46-3>
<1-21>26°
{-212}<-34-5>
<1-1-3>48°
{-8713}<25-3> 13
<-1-15>56°
{ }<13 11 –1>
<-211>63°
{3-4 11}<6 10 3>
<144>60°
{ }<-24-2>
<-210>36°
<1-1-1>64°
{-201}<23-8>
<112>65°
<-1-12>60°
{198}< >
<2-1-2>52° 10
<2-1-1>65°
<-1-12>60° 11 12
<-210>32°
<2-1-3>55°
<313>66°
<133>65°
<4-2-1>42°

17. Rex in HEAVILY DEFORMED OFHC COPPER
OIM map showing grain orientations after deformation to p = 3.6, UTS = MPa.

18. Color Key

19. Sh/B in HEAVILY DEFORMED OFHC COPPER
Shaded IQ map of a heavily drawn Cu ( = 3.2) showing regions of shear bands. 1 2
OIM maps of a heavily drawn Cu ( = 3.2) showing regions of shear bands.

21. Rex in HEAVILY DEFORMED OFHC COPPER CONCLUSION
Three regions were identified:
Low processing strain  < 2.5: No recrystallization, elongated structure.
Intermediate strain 2.5 <  < 3.2: Nucleation of recrystallization, shear bands formation. Shear bands occurred in grains with S{123}<634> orientation, and were inclined at 54° to the drawing direction. Their misorientation was between 5°s10°.
High strain  > 3.2: Extended recrystallization, recrystallized grains were mainly of Cube {001}<100> and S{123}<624> orientations.
OIM proved to be a viable tool in the study of heavily deformed materials.

22. HEAVILY DEFORMED Cu-Ag

23. HEAVILY DEFORMED CuAg
Optical micrograph of a heavily drawn CuAg ( = 3.2) showing regions of shear bands.
Shaded IQ map of a heavily drawn CuAg ( = 3.2) showing regions of shear bands.

24. HEAVILY DEFORMED Cu-Ag1 2
OIM maps of a heavily drawn CuAg ( = 3.18) showing regions of shear bands. The Grain boundaries were constructed with a misorientation criteria of 15°.

25. DEFORMED AND ANNEALED OFHC COPPER

26. ANNEALED OFHC COPPER - Microstructure
(a) Optical micrograph of annealed Cu, p = 3.1, 350°C
(a) Optical micrograph of annealed Cu, p = 3.1, 750°C

27. ANNEALED OFHC COPPER
OIM tiled IPF map showing grain orientations for Cu wire drawn to a strain of 3.1 and annealed at 250°C for 1 hr.

28. Color Key

29. ANNEALED OFHC COPPER
OIM tiled IPF map showing grain orientations for Cu wire drawn to a strain of 3.1 and annealed at 300°C for 1 hr.

30. ANNEALED OFHC COPPER
OIM tiled IPF map showing grain orientations for Cu wire drawn to a strain of 3.1 and annealed at 500°C for 1 hr.

31. ANNEALED OFHC COPPER
OIM tiled IPF map showing grain orientations for Cu wire drawn to a strain of 3.1 and annealed at 750°C for 1 hr.

32. ANNEALED OFHC COPPER: OIM-IPF
(a) Deformed Cu, p = 2.3
(b) Deformed Cu, p = 3.1

33. (a) Annealed Cu, p = 3.1, 250°C
(b) Annealed Cu, p = 3.1, 300°C
(c) Annealed Cu, p = 3.1, 500°C
(d) Annealed Cu, p = 3.1, 750°C

34. DEFORMED AND ANNEALED Cu-Nb/Ti

35. DEFORMED AND ANNEALED Cu-Nb/Ti
SEM micrograph of a heavily drawn Cu-Nb ( = 3.2) showing elongated Cu and Nb phases.
SEM micrograph of a heavily drawn Cu-Nb ( = 3.2) annealed at 500°C.

36. DEFORMED AND ANNEALED Cu-Nb/Ti
Annealed CuNb, p = 3.1, 250°C
(Nb phase extracted)

37. DEFORMED AND ANNEALED Cu-Nb/Ti
Annealed CuNb, p = 3.1, 300°C

38. DEFORMED AND ANNEALED Cu-Nb/Ti
Annealed CuNb, p = 3.1, 500°C

39. DEFORMED AND ANNEALED Cu-Nb/Ti
Annealed CuNb, p = 3.1, 750°C

40. Other Examples