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

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

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.

INTRODCUTION TO OIM - EBSP formation

INTRODCUTION TO OIM - Data acquisition

TECHNIQUE DEVELOPMENT

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

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

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

Image Quality Confidence Index Image Quality Confidence Index

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

Rex in HEAVILY DEFORMED OFHC COPPER

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.

Rex in HEAVILY DEFORMED OFHC COPPER U X V Y W DD (b) (a) OIM map showing grain orientations at (a) p = 2.3, UTS = 411.5 MPa, and (b) p = 3.2, UTS = 405 MPa. The lines represent high angle boundaries, with misorientation > 15o.

Rex in HEAVILY DEFORMED OFHC COPPER

<112>54° {-265}<-12 22 –7> <213>75° {-3 11 6}<-65-2> <-4-13>45° {1 11 18}<7 29 2> 1 <313>85° {184}<-12 17 2> <12-6>40° {-4-19}<-46-3> <1-21>26° {-212}<-34-5> <1-1-3>48° {-8713}<25-3> 13 <-1-15>56° {-2 14 23}<13 11 –1> <-211>63° {3-4 11}<6 10 3> <144>60° {-6 13 5}<-24-2> <-210>36° <1-1-1>64° {-201}<23-8> <112>65° <-1-12>60° {198}<12 23 2> <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°

Rex in HEAVILY DEFORMED OFHC COPPER OIM map showing grain orientations after deformation to p = 3.6, UTS = 390.5 MPa.

Color Key

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.

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.

HEAVILY DEFORMED Cu-Ag

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.

HEAVILY DEFORMED Cu-Ag 1 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°.

DEFORMED AND ANNEALED OFHC COPPER

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

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.

Color Key

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.

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.

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.

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

(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

DEFORMED AND ANNEALED Cu-Nb/Ti

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.

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

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

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

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

Other Examples