June_AMP_Digital

A D V A N C E D

M A T E R I A L S

P R O C E S S E S | J U N E

2 0 1 6

2 1

the heating process are listed in Table 1.

As shown in Table 1, among themisorien-

tation relationships observed between

the newly formed grain boundaries,

rotation axis about <1010>, <1120>, and

<1011> were prevalent. Grain boundar-

ies with orientation relationships corre-

sponding to {1012} extension twinning

(86° about <1120>), {1011} contraction

twinning (56° about <1120>), and (1012)

–(0112) extension double twinning (60°

about <1010>) were also commonly

observed. This was expected to be due to

the recovery and growth of twins formed

during the rolling process.

SUMMARY

An in-situ experimental technique,

which involves annealing inside an SEM

combined with EBSD analysis, was devel-

oped to understand the microstructural

evolution and recrystallization behavior

of rolled ZE20. Recrystallization started

at 423-473 K. A completely recrystallized

microstructure with relatively equiaxed

and strain-free grains was observed at

548-573K,andgraingrowthwasobserved

afterward. Misorientation angle-axis rela-

tionship analysis for the newly formed

grains reveals grain boundary formations

with various twin relationships. The char-

acterization methodology developed in

this work sets the stage for future exper-

iments to understand and control the

recrystallization behavior of commercial

alloys. Future work is targeted at employ-

ing this technique to understand the

effect of RE content on the recrystalliza-

tion behavior of Mg alloys.

~AM&P

For more information:

Carl J. Boehlert

is professor, Department of Chemical

Engineering and Materials Science,

Michigan State University, 428 South

Shaw Ln., Room 2527, East Lansing, MI,

48824-4437,

boehlert@egr.msu.edu

517.353.3703,

msu.edu

Acknowledgments

Funding for this research was sup-

ported by National Science Foundation

Division of Material Research (Grant No.

DMR1107117) through the Materials

World Network program. Vahid Kha-

demi, a Ph.D. student at Michigan State

University, is acknowledged for assis-

tance in developing the in-situ heating

stage setup.

References

1. S. Wright and M. Nowell, A Review of

in situ EBSD Studies,

Electron Backscat-

ter Diffraction in Materials Science,

p 329-337, 2009.

2. A. Luo, R. Mishra, and A. Sachdev,

High-Ductility Magnesium–Zinc–

Cerium Extrusion Alloys,

Scripta Mate-

rialia,

V 64.5, p 410-413, 2011.

3. S. Yi, et al., Mechanical Anisotropy

and Deep Drawing Behaviour of AZ31

and ZE10 Magnesium Alloy Sheets,

Acta

Materialia

V 58.2, p 592-605, 2010.

4. M. Perez-Prado and O. Ruano, Tex-

ture Evolution During Annealing of

Magnesium AZ31 Alloy,

Scripta Mate-

rialia,

V 46.2, p 149-155, 2002.

5. C. Boehlert, et al., In Situ Analysis of

the Tensile and Tensile-Creep Deforma-

tion Mechanisms in Rolled AZ31,

Acta

Materialia

, V 60.4, p 1889-1904, 2012.

6. J. Bohlen et al., The Texture and

Anisotropy of Magnesium–Zinc–Rare

Earth Alloy Sheets,

Acta Materialia

V 55.6, p 2101-2112, 2007.

7. A. Chakkedath, et al., The Effect of Nd

on the Tension and Compression Defor-

mation Behavior of Extruded Mg-1Mn

(wt%) at Temperatures Between 298 K

and 523 K (25° C and 250° C),

Metallurgi-

cal and Materials Transactions A

, V 45.8,

p 3254-3274, 2014.

8. S. Mohapatra and J. Jain, Overview

of Static Recrystallization in Magne-

sium Alloys,

Advanced Materials &

Processes,

p 28-31, 2015.

9. L. Mackenzie and M. Pekguleryuz,

The Recrystallization and Texture of

Magnesium–Zinc–Cerium Alloys,

Scripta

Materialia

V 59.6, p 665-668, 2008.

Fig. 3 —

EBSD IPF map (along the normal direction of the sample) after achieving 548 K. The

ID for each grain is highlighted. Ten new grains were formed during this heating step, which

resulted in 44 unique grain boundaries. The misorientation angle-axis relationships highlighted

by grey, purple, and tan shades correspond to {1012} extension twin, {1011} contraction twin,

(1012) – (0112) and extension double twin boundaries, respectively.

TABLE 1

—

CHARACTERISTICS OF THE NEWLY FORMED

GRAINS IN ROLLED ZE20 DURING IN-SITU HEATING

Characteristic

New grains

Number of new grains formed

Number of resulting unique grain boundaries

159

Grain boundaries with {1012} extension twin relationship (%)

Grain boundaries with {1011} contraction twin relationship (%)

Grain boundaries with (1012) – (0112) extension

double twin relationship (%)

Grain boundaries with <1010> rotation axis (%)

Grain boundaries with <1120> rotation axis (%)

Grain boundaries with <1011> rotation axis (%)