It's cute ( ) But does it DO anything??

Transcription

1 It's cute ( ) But does it DO anything??

2 Qualitative analysis - what IS this stuff?!! Every material has a unique x-ray powder pattern Every PHASE has a unique powder pattern This image, taken under a microscope, shows that a 'duplex stainless steel' has two phases 锈钢 This is the X-ray diffraction pattern

3 Qualitative analysis - what IS this stuff?!! The X-ray diffraction pattern tells us this How? FE AUS

4 Qualitative analysis - what IS this stuff?!! 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

5 Qualitative analysis - what IS this stuff?!! 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 1977 JCPDS became the International Centre for Diffraction Data (ICDD) - currently publishing various databases, including the new PDF-4, with diffraction and structure data for >300,000 phases

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17 Qualitative analysis - what IS this stuff?!! Make d, I list: Do search/match

18 Qualitative analysis - what IS this stuff?!! Example of page of search manual for Hanawalt manual search/match

19 Qualitative analysis - what IS this stuff?!! Make d, I list: Do search/match no match no MATCH! match 1 23 x - no match

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21 1. Qualitative analysis 2. Quantitative analysis 3. Crystal structure determination 4. Crystallite size 5. Microstrain 6. Residual macrostresses 观应?

22 1. Qualitative analysis 2. Quantitative analysis 3. Crystal structure determination 4. Crystallite size 5. Microstrain 6. Residual macrostresses stress = modulus x strain σ = E ε (Hooke's law)

23 Residual stress Reflections shift position (d-values change under stress)

24 Residual stresses

25 Residual stress Suppose isotropic solid loaded in uniaxial tension σ 1 Can measure change in interplanar spacing for planes reflecting as above Δd = (d - d o )/ d o - this is the strain ε 3 ε 3 = (1/E) (σ 3 - ν(σ 1 + σ 2 )) - ν is Poisson's ratio ε 3 = - (1/E) ν σ 1 - so, can get stress

26 Residual stress Biaxial & triaxial stress states more complicated Stress state resolved differently along different directions in sample, so peak shifts change w/ direction ε φψ = σ φ (1 + ν)/e sin 2 ψ (ν/e)(σ 1 + σ 2 ) σ 3 ψ σ φ σ 2 σ 1 φ

27 Residual stress Measurement procedure - classical technique - sin 2 ψ Diffractometer must have two more rotations - φ and ψ σ 3 ψ σ φ σ 2 σ 1 φ

28 Residual stress Measurement procedure - classical technique - sin 2 ψ φ = 0 ψ = 0 φ = 0 ψ = 45

29 Residual stress Measurement procedure - classical technique - sin 2 ψ ε φψ = σ φ (1 + ν)/e sin 2 ψ (ν/e)(σ 1 + σ 2 ) ε φψ slope Need E, ν - measure or calculate sin 2 ψ

30 1. Qualitative analysis 2. Quantitative analysis 3. Crystal structure determination 4. Crystallite size 5. Microstrain 6. Residual macrostresses 7. Thin films

31 Thin films

32 Thin films

33 Thin films

34 Thin films

35 Thin films Can rotate film and still get reflection

36 Thin films

37 1. Qualitative analysis 2. Quantitative analysis 3. Crystal structure determination 4. Crystallite size 5. Microstrain 6. Residual macrostresses 7. Thin films 8. Crystallinity 9. Studies of phase diagrams A. Phase boundaries B. Solid solutions C. 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