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Microstructure Characterization of Structural Materials by
Laser-assisted 3D Atom Probe
T.T. Sasaki, M.Z. Bian, T. Ohkubo, K. HonoNational Institute for Materials Science (NIMS), Tsukuba, Japan
SIP-IMASM 20172017/Oct/4
AIST, Tsukuba
Multi-scale microstructure analysis
Micro Nano Atomic
SEM
TextureGrain structure BSE
HAADF-STEM
Cs-corrected TEM 3DAP
SEM / EBSDCa+Mn
STEM-EDS
Surface Inside
3DAP
What’s visible in 3DAP
NdFeO
STEM/EDS
Nd+Pr
Cu~25nm
H. Sepehri-Amin et al., Acta Mater. 61, 819 (2012)
STEM/EDSGrain boundary in Nd-Fe-B magnet
GaN/GaInN V-defects
20nm
InGaNi
S. Tomiya et al. Appl. Phys. Lett. 98, 181904 (2011)
Zirconia Ceramics
Y. M. Chen et al. Scripta Mater. (2009).
Metallic Materials- Precipitates and solute segregation
along grain boundaries in various materials
33x33x100 nm
3DAP – Visualization of elemental distribution in 3D and in atomic scale
Multi-scale microstructure analysis needed!
Atomic
3DAP
Micro Nano
TextureGrain structure BSE
HAADF-STEM
3DAP
SEM / EBSDCa+Mn
STEM-EDS
Always need to make surewhere we are seeing in3DAP analysis
Happy with analysis only?
How to use 3DAP for microstructure analysis and materials development?
Body panelSheet
Magnesium alloy ~ can be a rival of CFRP?
Mg alloy Al alloy
a1
a2
c-axis
http://www.mg2015.org/
Requirements for sheet alloyExcellent room temperature formability- Low processing costUse of ubiquitous elements- Low materials costSatisfactory mechanical property
Porsche uses Mg sheet alloy
Wrought processing(Rolling, extrusion etc., )
Forming @ R.T.
T4Solution
treatment
Softening
ys~200 MPaf:>20%
ys:350MPaUTS :400MPa f:>15%
Aging
Aging10 nm
Strong and formable Mg sheet alloy
Mg-0.3Ca microalloyed with Al
J. Jayaraj et al. , Scripta Mater., (2010)
Mg-0.3Ca
Mg-0.3Ca-0.3Al
G.P. zones on basal plane
200ºC
Mg-0.3Ca
Mg-0.3Ca-0.3Al
G.P. zones in Mg-0.3Ca-0.3Al
Atomic number : Mg (12), Al (13), Ca (20)High magnification HAADF image, BD // [1120]
(0001)
0.52nm
Nothing visible in HAADF-STEM,,,
This is how we use 3DAP - G.P. zones in Mg-0.3Ca-0.3AlHigh magnification HAADF image, BD // [1120]
(0001)
0.52nm
~30nm
24nm
CaAl
Mg
Mg2(Al,Ca) type?Monolayer, or two-layers?
Micron-scale structure control to achieve excellent formability
(0002)
Max=13.7
4.5mm
(0002)
Max=3.5
7.7mm
Texture control by trace addition of Zn
Mg-1.1Al-0.5Ca-0.1Mn-0.3ZnMg-1.1Al-0.5Ca-0.1Mn
M.-Z. Bian, Scripta Mater. 138 (2017)151
0.0 0.1 0.2 0.30
100
200
300St
ress
(MPa
)
Strain
T6 T4
I.E.: 7.7 mm
204 MPa
144 MPa
Strengthening by precipitation hardening
20×20×100 (nm)Al CaM.-Z. Bian, Scripta Mater. 138 (2017)151
Benchmark
B.-C. Suh et al., Scripta Mater. 84–85 (2014) 1.S. Yi et al., Magnesium Technology 2016. (2016) 389.
M.-Z. Bian et al., Scripta Mater. 138 (2017) 151.
T6
This work
Commercial MgLDH=3~4 mm
Newly developed alloyLDH=7.7 mm
AlLDH=8.5 mm
Summary3DAP as a tool for materials development
Powerful tool to thoroughly analyze the chemistry of G.P. zones formed in Mg alloys. Enables in-depth understanding on the formation of G.P. zones.
G.P. zones in Mg-Ca based alloyG.P. zones are visible in 3DAP only in Mg-Ca-Alalloy.Monolayer, and has chemistry of Mg2(Ca,X)
Mg-Ca-Al-Mn-Zn alloy Formable at room temperatureHigh strength
Near- Titanium alloy Microstructure evolution during serviceEffect of a2 phase dispersion on the creep strength.Clarification of the formation mechanismof Silicide phase