Efficient High-Resolution Study of Dissimilar Metal Interfaces · •Tecnai F20 was used for TEM...
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Experimental Method • Plates of 6.6mm ASTM A516 Structural Steel and Ni-based Alloy 625 were welded by FSW • 300RPM, 100mm/min, 1.63mm offset, 30kN downward force, • Sample was mounted and polished; optical micrographs were taken. • An electron-transparent FIB lift-out foil made with FEI Helios Dual-Beam Focused Ion Beam (FIB) wa Nickel-Steel FSW Aluminum Steel VFAW Efficient High-Resolution Study of Dissimilar Metal Interfaces Genevieve Lee 1,2 , Ali Nassiri 2 , Guilherme Faria-Abreu 1,3 , Jonathan Orsborn 4,5 , Johnnatan Rodriguez 6 , Antonio J. Ramirez 1,3 1 Welding Engineering Program, 2 Center for Design and Manufacturing Excellence, 3 Manufacturing and Materials Joining Innovation Center – Ma2JIC, 4 Center for Electron Microscopy and Analysis, 5 Center for the Accelerated Maturation of Materials, 1,3,4,5 Department of Materials Science and Engineering, The Ohio State University, 6 EIA University, Envigado, Ant. Colombia Impact & Acknowledgements IMPACT • Scans using TKD and X-EDS provide characterization of crystallography and composition of a TEM foil in a matter of hours. This efficient technique may be a pivotal intermediate step after SEM imaging and TEM analysis to significantly. REFERENCES • Keller, R. R., and R. H. Geiss. J. Microsc., 2012, 245, (3), 245-251 • J.R. Fernandez, ‘Microstructural characterization of ASTM A516 - Ni based alloy 625 friction stir welded joints' (Doctoral Dissertation). 2013. • Fonda, R.W. and K. E. Knipling: Sci. Technol. Weld. Join., 2011, 16, (4), 288-293 ACKNOWLEDGEMENTS Thank you to S. Romo, B. Liu, G. Daehn for their support. Background & Motivation University of Quebec at Chicoutimi. www.uqac.ca • Transmission Kikuchi Diffraction (TKD), analogous to Electron Backscatter Diffraction (EBSD) is a technique that provides crystallographic analysis by diffraction of transmitted electrons in the Scanning Electron Microscope (SEM). Reduced interaction • Paired with Energy Dispersive X-ray Spectroscopy (X-EDS), sample composition and crystallography can be evaluated. • The high resolution rivals that of some conventional TEM analyses, and this intermediate analysis between SEM and TEM characterization can significantly reduce the onerous and time- and skill- intensive task work. • Solid-state welds are produced when nascent surfaces of metals are brought within interatomic distance, typically achieved by high heat or force. Solid state welds commonly undergo high stresses and exhibit refined microstructures unresolvable using regular EBSD. Interaction volume on TEM foil Electron Beam TKD / EBSD Detector http://www.ube-ind.co.jp • Transmission Kikuchi Diffraction (TKD), analogous to Electron Backscatter Diffraction (EBSD), gives crystallographic analysis by diffracting electrons in a Scanning Electron Microscope (SEM) on a TEM foil. Reduced interaction volume allows spatial resolutions down to 10nm. • Plates of 6.6mm ASTM A516 Structural Steel and Ni-based Alloy 625 were welded by FSW • 300RPM, 100mm/min, 1.63mm offset, 30kN downward force. • Aluminum 6111-T4 flyer welded to JSC980 steel substrate by VFAW • An electron-transparent FIB lift-out foil was used for TKD analysis. • XL-30 FEGSEM was used to conduct TKD and X-EDS analysis. • 30kV, 6 Spot Size, 100 μm aperture, 5-10mm WD, 20° sample Tilt. • Maps are made at 6-12nm step size. • Tecnai F20 was used for TEM analysis of foil 1 μm Ferrite (Steel) Austenite (Ni) Ferrite (Steel) Austenite (Ni) Fe K Ni K Cr K 1 μm 1 μm Mo L Nb L • Analysis was taken at the stir zone of the weld interface. TKD crystallography maps are shown at the left, and X-EDS mapping made simultaneously are at the right. Precipitates are Nb-rich and Mo-rich, suggesting NbC and Mo 6 C. • However, diffraction patterns of Mo-rich precipitates are identified as Cr-rich M 23 C 6 ; Transmission Kikuchi Patterns (TKPs) of M 6 C, space group “227”, and M 23 C 6 , space group “225”, are not differentiable as they are both FCC with lattice parameters ranging from 1.08-1.12nm. • TEM analysis of precipitates identify Mo-rich precipitates as M 6 C. • EDS composition data with selective area diffraction provides provides quantitative chemical analysis confirmation Above: IPF colored maps + IQ grayscale overlay. • Pole figures of interface shows simple shear textures • B texture component in Al-6111 • Shearing occurs with jetting mechanism of the VFAW impact Above: Phase color with IQ grayscale overlay. Above: X-EDS of matrix elements: iron, nickel, chromium. Ferrite Nickel NbC Above: X-EDS of precipitate elements: molybdenum, niobium. • Pole figures present texture from the FSW process, indicative of simple shear texture components • Corresponds to literature • BCC steel exhibits F shear component • FCC Ni has relatively weaker textures in A fiber PF of BCC (steel) on the left and FCC (Ni) on the right. JSC980 Steel Al-6111 2 mm AS Ni625 RS A516 A516 Ni625 Al-6111 JSC980 JSC980 Steel Al-6111 FSW cross section (top) and TEM thin foil (bottom) VFAW cross section (top) and thin foil (bottom) • Wavy interface commonly seen in impact welds • Intermediate shade suggests base metal dilution • Possible IMC formation • Shearing observed at the interface grains 1 μm • Aluminum FCC is on the left and steel BCC is on the right. IMC is not visible down the center of the map. • Grains are relatively small, down to 200 nm sizes within 5 μm of interface. • Aluminum grains are smaller towards the interface • Steel grains are more refined in general • IMCs are not resolved in map • EDS composition solutions FeAl 2 : 48%Al, Fe2Al5: 55%Al, FeAl3: 60%Al • TKD pattern solutions are FeAl2, FeAl, ferrite Element Weight % Atomic % KAB F Al K 53.04 70.04 Fe K 46.96 29.96 Ferrite FeAl FeAl 2 TKD maps of color IPF (N) with grayscale CI. Aluminum FCC is on the left and steel BCC is on the right. IMC is not visible down the center of the map. SEM micrograph of VFAW interface of aluminum and steel at wavy feature. BCC Ferrite FCC Aluminum FCC Nickel BCC Steel "Welding." Impulse Manufacturing Laboratory. The Ohio State University, n.d. Web. 16 Feb. 2017. https://iml.osu.edu/impulsed-based-metalworking/welding • Friction stir welding (FSW) is a solid state weld method that welds with moderate heat input and plastic deformation using a rotating pin tool. • Vaporized foil actuator weld (VFAW) is a new small scale collision weld technique that creates solid-state bonds with high energy impact. quantitative chemical analysis and further confirmation of M 6 C precipitate identification. • TEM work was limited to 6 hours. Location of the precipitates of interest were located on the foil prior to ocationted TEM imaging of foil, taken with STEM. Right: Mo-rich precipitate used for SAD and EDS. TEM characterization. TKD analysis provides a holistic, statistically sound understanding of a TEM foil and of the bulk sample.
Transcript of Efficient High-Resolution Study of Dissimilar Metal Interfaces · •Tecnai F20 was used for TEM...
Experimental Method • Plates of 6.6mm ASTM A516 Structural Steel
and Ni-based Alloy 625 were welded by FSW
• 300RPM, 100mm/min, 1.63mm offset, 30kN downward force,
• Sample was mounted and polished; optical micrographs were taken.
• An electron-transparent FIB lift-out foil made with FEI Helios Dual-Beam Focused Ion Beam (FIB) wa
Nickel-Steel FSW Aluminum Steel VFAW
Efficient High-Resolution Study of Dissimilar Metal Interfaces
Genevieve Lee1,2, Ali Nassiri2, Guilherme Faria-Abreu1,3, Jonathan Orsborn4,5, Johnnatan Rodriguez6, Antonio J. Ramirez1,3
1Welding Engineering Program, 2Center for Design and Manufacturing Excellence, 3Manufacturing and Materials Joining Innovation Center – Ma2JIC, 4Center for Electron Microscopy and
Analysis, 5Center for the Accelerated Maturation of Materials, 1,3,4,5Department of Materials Science and Engineering, The Ohio State University, 6EIA University, Envigado, Ant. Colombia
Impact & Acknowledgements
IMPACT • Scans using TKD and X-EDS provide characterization of
crystallography and composition of a TEM foil in a matter of hours. This efficient technique may be a pivotal intermediate step after SEM imaging and TEM analysis to significantly.
REFERENCES • Keller, R. R., and R. H. Geiss. J. Microsc., 2012, 245, (3), 245-251 • J.R. Fernandez, ‘Microstructural characterization of ASTM A516 - Ni based alloy 625
friction stir welded joints' (Doctoral Dissertation). 2013. • Fonda, R.W. and K. E. Knipling: Sci. Technol. Weld. Join., 2011, 16, (4), 288-293
ACKNOWLEDGEMENTS Thank you to S. Romo, B. Liu, G. Daehn for their support.
Background & Motivation
University of Quebec at Chicoutimi. www.uqac.ca
• Transmission Kikuchi Diffraction (TKD), analogous to Electron Backscatter Diffraction (EBSD) is a technique that provides crystallographic analysis by diffraction of transmitted electrons in the Scanning Electron Microscope (SEM). Reduced interaction
• Paired with Energy Dispersive X-ray Spectroscopy (X-EDS), sample composition and crystallography can be evaluated.
• The high resolution rivals that of some conventional TEM analyses, and this intermediate analysis between SEM and TEM characterization can significantly reduce the onerous and time- and skill- intensive task work.
• Solid-state welds are produced when nascent surfaces of metals are brought within interatomic distance, typically achieved by high heat or force. Solid state welds commonly undergo high stresses and exhibit refined microstructures unresolvable using regular EBSD.
Interaction volume on
TEM foil
Electron Beam
TKD / EBSD Detector
http://www.ube-ind.co.jp
• Transmission Kikuchi Diffraction (TKD), analogous to Electron Backscatter Diffraction (EBSD), gives crystallographic analysis by diffracting electrons in a Scanning Electron Microscope (SEM) on a TEM foil. Reduced interaction volume allows spatial resolutions down to 10nm.
• Plates of 6.6mm ASTM A516 Structural Steel and Ni-based Alloy 625 were welded by FSW
• 300RPM, 100mm/min, 1.63mm offset, 30kN downward force.
• Aluminum 6111-T4 flyer welded to JSC980 steel substrate by VFAW
• An electron-transparent FIB lift-out foil was used for TKD analysis.
• XL-30 FEGSEM was used to conduct TKD and X-EDS analysis.
• 30kV, 6 Spot Size, 100 μm aperture, 5-10mm WD, 20° sample Tilt.
• Maps are made at 6-12nm step size.
• Tecnai F20 was used for TEM analysis of foil
1 μm
Ferrite (Steel)
Austenite (Ni)
Ferrite (Steel)
Austenite (Ni)
Fe K Ni K Cr K
1 μm
1 μm
Mo L Nb L
• Analysis was taken at the stir zone of the weld interface. TKD crystallography maps are shown at the left, and X-EDS mapping made simultaneously are at the right. Precipitates are Nb-rich and Mo-rich, suggesting NbC and Mo6C.
• However, diffraction patterns of Mo-rich precipitates are identified as Cr-rich M23C6; Transmission Kikuchi Patterns (TKPs) of M6C, space group “227”, and M23C6, space group “225”, are not differentiable as they are both FCC with lattice parameters ranging from 1.08-1.12nm.
• TEM analysis of precipitates identify Mo-rich precipitates as M6C.
• EDS composition data with selective area diffraction provides provides quantitative chemical analysis confirmation
Above: IPF colored maps + IQ grayscale overlay.
• Pole figures of interface shows simple shear textures
• B texture component in Al-6111
• Shearing occurs with jetting mechanism of the VFAW impact
Above: Phase color with IQ grayscale overlay.
Above: X-EDS of matrix elements: iron, nickel, chromium. Ferrite Nickel NbC
Above: X-EDS of precipitate elements: molybdenum, niobium.
• Pole figures present texture from the FSW process, indicative of simple shear texture components
• Corresponds to literature
• BCC steel exhibits F shear component
• FCC Ni has relatively weaker textures in A fiber PF of BCC (steel) on the left and FCC (Ni) on the right.
JSC980 Steel
Al-6111
2 mm
AS Ni625 RS A516
A516 Ni625
Al-6111 JSC980
JSC980 Steel
Al-6111
FSW cross section (top) and TEM thin foil (bottom)
VFAW cross section (top) and thin foil (bottom)
• Wavy interface commonly seen in impact welds
• Intermediate shade suggests base metal dilution
• Possible IMC formation
• Shearing observed at the interface grains
1 µm
• Aluminum FCC is on the left and steel BCC is on the right. IMC is not visible down the center of the map.
• Grains are relatively small, down to 200 nm sizes within 5 µm of interface.
• Aluminum grains are smaller towards the interface
• Steel grains are more refined in general
• IMCs are not resolved in map
• EDS composition solutions FeAl2: 48%Al, Fe2Al5: 55%Al, FeAl3: 60%Al
• TKD pattern solutions are FeAl2, FeAl, ferrite
Element Weight % Atomic % KAB FactorNet Int. Net Error %
Al K 53.04 70.04 1 2034.8 1.01
Fe K 46.96 29.96 2.59 695.2 1.71Ferrite FeAl FeAl2
TKD maps of color IPF (N) with grayscale CI. Aluminum FCC is on the left and steel BCC is on the right. IMC is not visible down the center of the map.
SEM micrograph of VFAW interface of aluminum and steel at wavy feature.
BCC Ferrite
FCC Aluminum
FCC Nickel BCC Steel
"Welding." Impulse Manufacturing Laboratory. The Ohio State University, n.d. Web. 16 Feb. 2017. https://iml.osu.edu/impulsed-based-metalworking/welding
• Friction stir welding (FSW) is a solid state weld method that welds with moderate heat input and plastic deformation using a rotating pin tool.
• Vaporized foil actuator weld (VFAW) is a new small scale collision weld technique that creates solid-state bonds with high energy impact. quantitative chemical analysis and
further confirmation of M6C precipitate identification.
• TEM work was limited to 6 hours. Location of the precipitates of interest were located on the foil prior to ocationted
TEM imaging of foil, taken with STEM. Right: Mo-rich precipitate used for SAD and EDS.
TEM characterization. TKD analysis provides a holistic, statistically sound understanding of a TEM foil and of the bulk sample.
