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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
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IN-SITU EBSD TECHNIQUE
CHARACTERIZES
MICROSTRUCTURE EVOLUTION
OF MAGNESIUM ALLOY
An in-situ annealing technique combined with EBSD characterizes the
microstructural evolution of an Mg alloy as a function of temperature.
Ajith Chakkedath, Carl Boehlert,* and David Hernandez, Michigan State University, East Lansing
Jan Bohlen, Sangbong Yi, and Dietmar Letzig, Magnesium Innovation Centre MagIC, Germany
I
n-situ scanning electron micros-
copy (SEM) enables microstructure
evolution to be studied under vari-
ous loading conditions. Modern SEMs
incorporate heating assemblies so they
can be tilted to the optimum angle for
electron backscatter diffraction (EBSD)
analysis. This, combined with the fast
indexing capabilities of fully automated
modern EBSD systems, enables micro-
structure evolution to be captured
during in-situ heating experiments.
In-situ EBSD heating experiments
are typically performed to enable
understanding of phase transforma-
tions and/or recrystallization behavior
as a function of temperature and/or
time
[1]
. Such experiments have been
used to study the microstructural
evolution and recrystallization in alu-
minum alloys, copper, titanium, and
steel
[1]
. Similar studies help explain the
microstructural evolution in wrought
magnesium (Mg) alloys, in which the
crystallographic texture has significant
influence on elongation-to-failure
[2]
and
anisotropy in mechanical properties
[3]
.
Control of the crystallographic
texture in wrought Mg alloys is of
commercial interest. Conventional
Mg alloys tend to form strong texture
during wrought processing and retain
that texture after annealing
[4,5]
, which
Fig. 1 —
Heating stage used for in-situ heating experiments. The sample (not shown) was placed
directly on top of the heating element during experiments.
makes further processing difficult. Rare
earth (RE) containing Mg alloys form
weaker textures during wrought pro-
cessing (and subsequent annealing)
[6,7]
.
However, the underlying mechanisms
responsible for this texture develop-
ment in Mg alloys during annealing are
not well understood
[8,9]
. Therefore, an
in-situ annealing technique combined
with EBSD was developed in order to
characterize the microstructural evolu-
tion as a function of temperature in a
RE-containing Mg alloy, Mg-2Zn-0.2Ce
(wt%) (ZE20).
*Member of ASM International