In-situ Studies

Fatigue-corrosion

The fatigue-corrosion data sets [B39] 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		1235
tomo_00033	1500	H14_7075PA_172HV_99NF_01500C		1235
tomo_00034	2000	H14_7075PA_172HV_99NF_02000C		1235
tomo_00035	2750	H14_7075PA_172HV_99NF_02750C		1235
tomo_00036	3500	H14_7075PA_172HV_99NF_03500C		1235
tomo_00037	4000	H14_7075PA_172HV_99NF_04000C		1235
tomo_00038	4500	H14_7075PA_172HV_99NF_04500C		1235
tomo_00039	5500	H14_7075PA_172HV_99NF_05500C		1235
tomo_00040	6500	H14_7075PA_172HV_99NF_06500C		1235
tomo_00041	7500	H14_7075PA_172HV_99NF_07500C		1235
tomo_00042	8500	H14_7075PA_172HV_99NF_08500C		1235
tomo_00043	10000	H14_7075PA_172HV_99NF_10000C		1235
tomo_00044	12000	H14_7075PA_172HV_99NF_10000C		1235
tomo_00045	13000	H14_7075PA_172HV_99NF_13000C		1235
tomo_00046	13100	H14_7075PA_172HV_99NF_13100C		1235
tomo_00047	13200	H14_7075PA_172HV_99NF_13200C		1235
tomo_00048	13300	H14_7075PA_172HV_99NF_13300C		1235
tomo_00049	13400	H14_7075PA_172HV_99NF_13400C		1235
tomo_00050	13800	H14_7075PA_172HV_99NF_13800C		1235
tomo_00051	13900	H14_7075PA_172HV_99NF_13900C		1235
tomo_00052	14000	H14_7075PA_172HV_99NF_14000C		1235
tomo_00053	14100	H14_7075PA_172HV_99NF_14100C		1235
tomo_00054	14200	H14_7075PA_172HV_99NF_14200C		1235
tomo_00055	14300	H14_7075PA_172HV_99NF_14300C		1235
tomo_00056	14346	H14_7075PA_172HV_99NF_14346C		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.

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		1232	740/1700	[141,226]
tomo_00008	0.57(*)	20577	Ce6Al4_5P7kbar		1321	1000/1440	[141,228]
tomo_00009	2	23431	Ce6Al4_20kbar		1219	550/1370	[147,233]
tomo_00010	8.59	19313	Ce6Al4_8P59GPa		1286	740/1500	[142,227]
tomo_00011	13.37	18518	Ce6Al4_13P37GPa		1292	620/1320	[140,226]
tomo_00012	17.44	17626	Ce6Al4_17p44GPa		1116	800/1200	[140,225]
tomo_00013	19	17735	Ce6Al4_19GPa		1314	610/1500	[71,113]
tomo_00014	21.39	17129	Ce6Al4_21p39GPa		1140	610/1200	[140,226]
tomo_00015	26.17	16557	Ce6Al4_26p17GPa		1124	740/1270	[140,227]
tomo_00016	29.5	16304	Ce6Al4_29P5GPa		1338	760/1180	[140,227]
tomo_00017	33.07	15677	Ce6Al4_33p07GPa		1232	710/1210	[140,227]
tomo_00018	41.88	15164	Ce6Al4_41p88GPa		1292	700/1180	[138,225]
tomo_00019	47.89	14737	Ce6Al4_47p89GPa		1114	740/1210	[141,228]
tomo_00020	54.73	14328	Ce6Al4_54p73GPa		1352	750/1230	[138, 224]
tomo_00021	59	14335	Ce6Al4_59GPa		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		952
tomo_00026	Rock oil saturated		957

Rock no oil

tomo_ID	00025
Image preview
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
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