In-situ Studies

Fatigue-corrosion

The fatigue-corrosion data sets [B40] contain micro tomography (microCT) data with the experimental conditions reported in the table below [B6]:

Instrument

APS 2-BM-A fast tomo

Energy

27.4 keV

Monochromator

multi-layer

Scan Range

180 degree

Number of Projections

1500

White Fields

10 before

Dark Fields

10 before

Mode

fly-scan

Rotation Speed

0.75 deg/s

Sample Detector Distance

60 mm

Attenuator

mm C + 1mm Glass

Detector Name

PCO edge

Exposure Time

0.0001 s

Pixel Size

0.65 µm

Detector shutter mode

global

Detector Dimension x

2560

Detector Dimension y

2160

Objective Magnification

Mitutoyo 10x

Scintillator

LuAG 10 µm

The fatigue-corrision data sets includes 25 tomographic data sets collected at different fatigue cycle ranging from 750 to 14346 as reported in the table below:

To load the data sets and perform a basic reconstruction using tomopy

tomopy recon --file-name tomo_00032.h5 --rotation-axis 1235

To enable phase retrieval use the retrieve-phase options of tomopy cli or type:

tomopy recon -h

for all options.

Tomo ID

Cycles

Sample Name

Image

Axis

tomo_00032

750

H14_7075PA_172HV_99NF_00750C

00032

1235

tomo_00033

1500

H14_7075PA_172HV_99NF_01500C

00032

1235

tomo_00034

2000

H14_7075PA_172HV_99NF_02000C

00032

1235

tomo_00035

2750

H14_7075PA_172HV_99NF_02750C

00032

1235

tomo_00036

3500

H14_7075PA_172HV_99NF_03500C

00032

1235

tomo_00037

4000

H14_7075PA_172HV_99NF_04000C

00032

1235

tomo_00038

4500

H14_7075PA_172HV_99NF_04500C

00032

1235

tomo_00039

5500

H14_7075PA_172HV_99NF_05500C

00032

1235

tomo_00040

6500

H14_7075PA_172HV_99NF_06500C

00032

1235

tomo_00041

7500

H14_7075PA_172HV_99NF_07500C

00032

1235

tomo_00042

8500

H14_7075PA_172HV_99NF_08500C

00032

1235

tomo_00043

10000

H14_7075PA_172HV_99NF_10000C

00032

1235

tomo_00044

12000

H14_7075PA_172HV_99NF_10000C

00032

1235

tomo_00045

13000

H14_7075PA_172HV_99NF_13000C

00032

1235

tomo_00046

13100

H14_7075PA_172HV_99NF_13100C

00032

1235

tomo_00047

13200

H14_7075PA_172HV_99NF_13200C

00032

1235

tomo_00048

13300

H14_7075PA_172HV_99NF_13300C

00032

1235

tomo_00049

13400

H14_7075PA_172HV_99NF_13400C

00032

1235

tomo_00050

13800

H14_7075PA_172HV_99NF_13800C

00032

1235

tomo_00051

13900

H14_7075PA_172HV_99NF_13900C

00032

1235

tomo_00052

14000

H14_7075PA_172HV_99NF_14000C

00032

1235

tomo_00053

14100

H14_7075PA_172HV_99NF_14100C

00032

1235

tomo_00054

14200

H14_7075PA_172HV_99NF_14200C

00032

1235

tomo_00055

14300

H14_7075PA_172HV_99NF_14300C

00032

1235

tomo_00056

14346

H14_7075PA_172HV_99NF_14346C

00032

1235

X-ray synchrotron tomography was used to visualize the fatigue crack initiation and growth from corrosion pits in Al7075 aluminum alloys. Peak-aged Al 7075 samples were corrosion-pitted by soaking in exposed 3.5 wt.% NaCl solution for fifteen days (360 hours). These samples were fatigue tested in situ in solution using synchrotron X-ray tomography to analyze the fatigue crack initiation and growth characteristics (4D). Hydrogen bubbles were observed within the cracks during fatigue crack growth, indicating chemical changes in the sample during corrosion fatigue.

project

Top figure shows an X-ray projection. The reconstruction is from 14300 fatigue cycles and shows the fatigue crack initiating from pre-existing “mud cracks” within the corrosion products in pits on the surface of the sample. The 4D data allowed measurement of the microscopic bubbles in the crack, which appeared to grow preferentially near the impurity particles within the alloy. With these 4D insights, alloys of improved corrosion-cracking resistance can be created and more durable aerospace components can eventually reach the market.

Three-dimensional (3D) tomography under load is required to gain complete understanding of the growth rate of tortuous crack geometry within engineered components. When corrosion is involved, the four-dimensional (3D plus time) tomography is required to capture the stress-corrosion cracking phenomena because corrosion reactions occur rapidly upon exposure of the unpassivated metal crack faces to corrosive solution. These corrosion and cracking mechanisms work synergistically to change the properties of the sample while producing microscopic hydrogen bubbles as evidence of their damage. Only with the high brilliance and stability of monochromatic synchrotron X-rays can accurate measurement of these bubbles be performed to identify the corrosion-cracking mechanisms. The work below demonstrates one such example to find the mechanisms behind corrosion-fatigue cracking from corrosion pits in peak-aged Al7075, which is a relevant source of failure in aerospace industry component reliability.

High Pressure

The High Pressure data set contains nano tomography (nanoCT) data with the experimental conditions reported in the table below.

Instrument

APS 32-ID TXM

Energy

8000 eV

Monochromator

double crystal Si (1,1,1)

Scan Range

180 degree

Number of Projections

359

White Fields

20 before

Dark Fields

8 before

Exposure Time

15 s

PixelSize

13.8 nm

Comment

10x 60 nm ZP

The sample consisting is a small particle of Ce 6 Al 4 undergoing a pressure increase.

The High Pressure data sets consists of 15 tomographic data sets, each nanoCT data set is collected after a pressure increase from 0.3 GPa to 59 GPa as reported in the table below. Because the sample is into a high pressure cell, 86 of the 359 projections are blocked by the load frame (limited view problem). The index of the blocked view angles together with the particles location for each data set (slice_first, slice_start) are reported in the table below.

To load the data sets and perform a basic reconstruction using tomopy

tomopy recon --file-name tomo_00007.h5 --rotation-axis 1232 --nsino 0.7

To enable blocked view reconstruction use the blocked-views options of tomopy cli or type:

tomopy recon -h

for all options.

Tomo ID

GPa

Volume

Sample Name

Image

Axis

Slice first/last

Blocked Views

tomo_00007

0.3

24602

Ce6Al4_3kbar

00007

1232

740/1700

[141,226]

tomo_00008

0.57(*)

20577

Ce6Al4_5P7kbar

00007

1321

1000/1440

[141,228]

tomo_00009

2

23431

Ce6Al4_20kbar

00007

1219

550/1370

[147,233]

tomo_00010

8.59

19313

Ce6Al4_8P59GPa

00007

1286

740/1500

[142,227]

tomo_00011

13.37

18518

Ce6Al4_13P37GPa

00007

1292

620/1320

[140,226]

tomo_00012

17.44

17626

Ce6Al4_17p44GPa

00007

1116

800/1200

[140,225]

tomo_00013

19

17735

Ce6Al4_19GPa

00007

1314

610/1500

[71,113]

tomo_00014

21.39

17129

Ce6Al4_21p39GPa

00007

1140

610/1200

[140,226]

tomo_00015

26.17

16557

Ce6Al4_26p17GPa

00007

1124

740/1270

[140,227]

tomo_00016

29.5

16304

Ce6Al4_29P5GPa

00007

1338

760/1180

[140,227]

tomo_00017

33.07

15677

Ce6Al4_33p07GPa

00007

1232

710/1210

[140,227]

tomo_00018

41.88

15164

Ce6Al4_41p88GPa

00007

1292

700/1180

[138,225]

tomo_00019

47.89

14737

Ce6Al4_47p89GPa

00007

1114

740/1210

[141,228]

tomo_00020

54.73

14328

Ce6Al4_54p73GPa

00007

1352

750/1230

[138, 224]

tomo_00021

59

14335

Ce6Al4_59GPa

00007

1352

630/1100

[138, 224]

(*) was the one acquired with 5x instead of 10x optics

Rock Permeability

The microCT data sets of these samples were acquired at the SYRMEP beamline of Elettra-Sincrotrone Trieste (Elettra), Italy in nearly-parallel beam geometry. The related sample description and the experimental conditions are reported in tables below under tomo_00025 to tomo_00026.

To load the data sets and perform a basic reconstruction using tomopy

tomopy recon --file-name tomo_00025.h5 --rotation-axis 952

tomo_ID

Sample Name

Image

Axis

tomo_00025

Rock no oil

00025

952

tomo_00026

Rock oil saturated

00026

957

Rock no oil

tomo_ID

00025

Image preview

00025

Download

tomo_00025

Instrument

Elettra Syrmep

Sample name

Rock no oil

X-ray energy

white beam mode

Ring energy

2 GeV

Exposure time

1 s

Detector

SCMOS 16-bit

Sample-to-detector distance

150 mm

Pixel size

2.04 µm

Scan Range

180 degree

Number of Projections

400

Rotation axis location

952

Rock oil saturated

tomo_ID

00026

Image preview

00026

Download

tomo_00026

Instrument

Elettra Syrmep

Sample name

Rock oil saturated

X-ray energy

white beam mode

Ring energy

2 GeV

Exposure time

1 s

Detector

SCMOS 16-bit

Sample-to-detector distance

150 mm

Pixel size

2.04 µm

Scan Range

180 degree

Number of Projections

400

Rotation axis location

957