it's cute ( 可爱 )……… but does it do anything??. this image, taken under a microscope,...

It's cute (可爱 )………It's cute (可爱 )………

But does it DO anything??

But does it DO anything??

This image, taken under a microscope, shows that a 'duplex stainless steel' has two phases - austenite (AUS) & ferrite (FE)

This image, taken under a microscope, shows that a 'duplex stainless steel' has two phases - austenite (AUS) & ferrite (FE)

Powder diffraction - applicationsPowder diffraction - applications

Qualitative analysis - what IS this stuff?!! Qualitative analysis - what IS this stuff?!!

Every material has a unique x-ray powder pattern

Every PHASE has a unique powder pattern

Every material has a unique x-ray powder pattern

Every PHASE has a unique powder pattern

AUS

FE

This is the X-ray diffraction patternThis is the X-ray diffraction pattern



AUS

FE

The X-ray diffraction pattern tells us this

The X-ray diffraction pattern tells us this

How?How?



We use the Powder Diffraction File database (the PDF) and a search system


History

1938 Hanawalt paper on first database and search method

1941 ASTM committee publishes database on cards

1969 JCPDS incorporated; publishes the JCPDF

History



1969 JCPDS incorporated; publishes the JCPDF





History



1969 JCPDS incorporated; publishes the JCPDF1977 JCPDS became the International Centre for

Diffraction Data (ICDD) - currently publishing various databases, including the new PDF-4, with diffraction and structure data for >240,000 phases

History



1969 JCPDS incorporated; publishes the JCPDF1977 JCPDS became the International Centre for

Diffraction Data (ICDD) - currently publishing various databases, including the new PDF-4, with diffraction and structure data for >240,000 phases



Make d, I list:

2.080 100 1 1.081 30 62.025 100 2 1.040 12 1.798 45 4 1.018 20 81.433 20 0.907 35 51.272 26 7 0.898 31.170 50 3 0.830 14

Make d, I list:

2.080 100 1 1.081 30 62.025 100 2 1.040 12 1.798 45 4 1.018 20 81.433 20 0.907 35 51.272 26 7 0.898 31.170 50 3 0.830 14

Do search/matchDo search/match



Example of page of search manual for Hanawalt manual search/matchExample of page of search manual for Hanawalt manual search/match



Make d, I list:

2.080 100 1 1.081 30 62.025 100 2 1.040 12 1.798 45 4 1.018 20 81.433 20 0.907 35 51.272 26 7 0.898 31.170 50 3 0.830 14

Make d, I list:

2.080 100 1 1.081 30 62.025 100 2 1.040 12 1.798 45 4 1.018 20 81.433 20 0.907 35 51.272 26 7 0.898 31.170 50 3 0.830 14

1 2 3 - no match1 2 4 - no match1 2 x - no match




1 4 5 - no match1 4 6 - MATCH! 1 4 5 - no match1 4 6 - MATCH!

Do search/matchDo search/match


1. Qualitative analysis2. Quantitative analysis 3. Crystal structure determination4. Crystallite size5. Microstrain 6. Residual macrostresses


?




stress = modulus x strain = E

(Hooke's law)

stress = modulus x strain = E

(Hooke's law)


Residual stress

Reflections shift position (d-values change under stress)

Residual stress

Reflections shift position (d-values change under stress)


Residual stressesResidual stresses

Residual stress

Suppose isotropic solid loaded in uniaxial tension

Residual stress

Suppose isotropic solid loaded in uniaxial tension

Can measure change in interplanar spacing for planes reflecting as above

d = (d - do)/ do - this is the strain

Can measure change in interplanar spacing for planes reflecting as above

d = (d - do)/ do - this is the strain

= (1/E) (- ( + )) - is Poisson's ratio

= - (1/E) - so, can get stress

= (1/E) (- ( + )) - is Poisson's ratio

= - (1/E) - so, can get stress

Residual stress

Biaxial & triaxial stress states more complicated

Stress state resolved differently along different directions in sample, so peak shifts change w/ direction

Residual stress

Biaxial & triaxial stress states more complicated

Stress state resolved differently along different directions in sample, so peak shifts change w/ direction

= (1 + )/E sin2 /E)(+ = (1 + )/E sin2 /E)(+

Residual stress

Measurement procedure - classical technique - sin2

Residual stress


Diffractometer must have two more rotations -

and Diffractometer must have two more rotations -

and

Residual stress


Residual stress


Residual stress


Residual stress


= (1 + )/E sin2 /E)(+ = (1 + )/E sin2 /E)(+

sin2

slopeslopeNeed E, -measure orcalculate

Need E, -measure orcalculate


1. Qualitative analysis2. Quantitative analysis 3. Crystal structure determination4. Crystallite size5. Microstrain 6. Residual macrostresses 7. Thin films

1. Qualitative analysis2. Quantitative analysis 3. Crystal structure determination4. Crystallite size5. Microstrain 6. Residual macrostresses 7. Thin films


Thin films Thin films



Can rotatefilm and still get reflection


1. Qualitative analysis2. Quantitative analysis 3. Crystal structure determination4. Crystallite size5. Microstrain 6. Residual macrostresses 7. Thin films8. Crystallinity9. Studies of phase diagrams

A. Phase boundariesB. Solid solutionsC. Phase transitions

10. Studies of chemical reactions and identification of reaction products.

11. Determination of grain sizes.12. Preferred orientation in

polycrystalline bodies.13. Many more

1. Qualitative analysis2. Quantitative analysis 3. Crystal structure determination4. Crystallite size5. Microstrain 6. Residual macrostresses 7. Thin films8. Crystallinity9. Studies of phase diagrams

A. Phase boundariesB. Solid solutionsC. Phase transitions

10. Studies of chemical reactions and identification of reaction products.

11. Determination of grain sizes.12. Preferred orientation in

polycrystalline bodies.13. Many more

it's cute ( 可爱 )……… but does it do anything??. this image, taken under a microscope,...

Documents

jcpdf slide

phases slide

diffraction data icdd

unique xray powder

search manual

search method

unique powder pattern

hanawalt paper