From Solidification Processing to Microstructure to Mechanical Properties: A Multi-scale X-ray Study of an Al-Cu Alloy Sample
From Solidification Processing to Microstructure to Mechanical Properties: A Multi-scale X-ray Study of an Al-Cu Alloy Sample
D. TOURRET 0
J.C.E. MERTENS 0
E. LIEBERMAN 0
S.D. IMHOFF 0
J.W. GIBBS 0
K. HENDERSON 0
K. FEZZAA 0
A.L. DERIY 0
T. SUN 0
R.A. LEBENSOHN 0
B.M. PATTERSON 0
A.J. CLARKE 0
0 D. TOURRET is with the Sigma Division, Los Alamos National Laboratory , P.O. Box 1663, Los Alamos, NM 87545 , and also with the IMDEA Materials Institute , Calle Eric Kandel 2, 28906 Getafe, Madrid , Spain. J.C.E. MERTENS, E. LIEBERMAN, K. HENDERSON, R.A. LEBENSOHN, and B.M. PATTERSON are with the Materials Science and Technology Division, Los Alamos National Laboratory , P.O. Box 1663 , Los Alamos, NM 87545. S.D. IMHOFF and J.W. GIBBS are with the Sigma Division, Los Alamos National Laboratory. K. FEZZAA, A.L. DERIY, and T. SUN are with the Argonne National Laboratory, Advanced Photon Source, Lemont, IL 60439. A.J. CLARKE is with the Sigma Division, Los Alamos National Laboratory, and also with the Department of Metallurgical and Materials Engineering, Colorado School of Mines , 1500 Illinois Street, Golden, CO 80401. Contact
We follow an Al-12 at. pct Cu alloy sample from the liquid state to mechanical failure, using in situ X-ray radiography during directional solidification and tensile testing, as well as three-dimensional computed tomography of the microstructure before and after mechanical testing. The solidification processing stage is simulated with a multi-scale dendritic needle network model, and the micromechanical behavior of the solidified microstructure is simulated using voxelized tomography data and an elasto-viscoplastic fast Fourier transform model. This study demonstrates the feasibility of direct in situ monitoring of a metal alloy microstructure from the liquid processing stage up to its mechanical failure, supported by quantitative simulations of microstructure formation and its mechanical behavior.
I. INTRODUCTION
PROGRESS in understanding the links between
processing routes, microstructures, properties, and
performance of structural technological materials depends
on our ability to observe materials in situ throughout
their life cycle, and to quantitatively simulate these
individual links.
In terms of in situ imaging, the use of X-ray
radiography and computed tomography has spread
rapidly within most branches of materials science within
the past two decades.[
1
] These techniques are particularly
relevant to metallic alloys, and have been extensively
employed in solidification processing,[
2–5
]
three-dimensional (3D) rendering of microstructures and their
evolution,[2] and in experimental mechanics.[
6
] X-ray
imaging, in particular 3D tomography, has reached a
sufficient level of maturity to be capable of providing
quantitative measurements.[
7
]
Solidification processing of metallic alloys (and in
particular aluminum-based alloys) has been thoroughly
investigated using two-dimensional (2D) radiography of
thin sample experiments, often in controlled directional
solidification conditions.[
8–22
] Resulting studies shed
light onto mechanisms such as morphological
transitions,[
8–11
] dendritic and eutectic growth,[
11–15
] dendritic
fragmentation,[
16–20
] gravity-induced buoyancy and
solute transport,[
15–17,20,21
] and the formation of major
solidification defects such as freckles.[
21,22
]
Metallic alloy solidification and microstructure
evolution have also been extensively studied using 3D
computed tomography.[
23–31
] Studies have mostly
focused on mechanisms of solidification at low growth
rates,[
23,24
] dendritic coarsening,[25] morphological
transitions of equiaxed grains,[
31
] or the formation of
intermetallics.[
26,27
] Recently, advanced techniques to
increase temporal resolution have allowed resolving the
evolution of complex dendritic morphologies at higher
cooling rates[
28,29
] and exploring cellular-to-dendritic
morphological transitions.[
30
]
Computed X-ray tomography has also become
widespread in the field of experimental mechanics. It has
primarily been used to observe mechanical testing of
polymers (e.g., Reference 32), metallic alloys (e.g.,
References 33 through 35), and metallic foams
(e.g., References 36 and 37). Recent advances in fast
tomography now allow observing the progression of a
crack during fracture of materials of increasingly lower
ductility (e.g., up to 20 Hz[
38
]).
At the crossroads of processing and properties, X-ray
in situ imaging has also been extensively used to
investigate the mechanical behavior of semi-solid
materials.[
39–48
] Such studies, usually realized for isothermal
conditions with a partially melted sample, have helped
to determine key mechanisms of failure or defect
formation in a state of tension, e.g., linking the mushy
zone permeability and the lack of liquid feeding to hot
tearing defects,[
40,43,44
] as well as in compression,[
45–48
]
highlighting the opening of internal pores[
(...truncated)