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

Our results – reported worldwide

日刊工業新聞

China

IMA NewsASM

Near- Titanium alloys

Compressor blades

Microstructure of near- Titanium alloy

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