1. In-situ Resistivity Measurement during Annealing and Transmission Electron Microscopy – an Efficient Method of Investigation of Phase Transformation in Al Alloys M. Cieslar 1, M. Slámová 2, M. Hájek 1, J. Veselý 1 1 Charles University in Prague, Faculty of Mathematics and Physics, Ke Karovu 5, 121 16 Prague 2, Czech Republic 2 VÚK Panenské Břežany, s.r.o., Panenské Břežany 50, 250 70 Odolena Voda, Czech Republic

2. Properties changes in materials 1. Changes of integral properties 2. The role of microstructure

3. Integral experimental techniques DSC (DTA) Hardness test Tensile test (compression) … Resistivity measurements

4. Microstructure observations Light microscopy X-ray diffractometry Scanning electron microscopy Transmission electron microscopy

5. Complex information Suitable combination of integral and microstructural methods

6. Aluminium alloys Resistivity measurement Hardness test Light microscopy SEM TEM

7. Resistivity measurements Matthiessen’s rule  (T)=  m (T) +  d  m (T) … scattering on phonons  d … residual resistivity

8. Residual resistivity  d =  k k=kckk=kck c k … concentration (density, volume fraction, …) of defects  k … concentration and temperature independent constant

9. Deviations from Matthiessen’s rule  k is not a constant 1.Concentration 2.Temperature 3.Configuration

10. Electrical resistivity methods Residual resistivity measurement (  d ) in liquid nitrogen In-situ resistivity measurements during linear heating (  (T)=  m (T) +  d )

11. Twin-roll-cast AW-3003 alloys Influence of Si content and prestrain

12. Effect of Mn, Si content and prestrain  = 0.5 (F5, S5, Z5)  = 3.9 (F04, S04, 04)

13. Hardness measurements  = 0.5 (F5, S5, Z5)  = 3.9 (F04, S04, 04)

14. Microstructure (TEM) Deformation substructure in as-rolled Z04 Deformation substructure in the initial state of the S5 specimen First precipitates in the partially recovered substructure of the S5 specimen annealed to 320°C

15. Microstructure evolution I Precipitates in the S5 specimen annealed up to 450°C Inhomogeneous precipitation in the Z5 specimen annealed up to 450°C Coarsening and partial redissolution of phases in the S5 specimen annealed up to 620°C

16. Integral methods

17. Interpretation First minimum: Transformation of primary phases Second minimum: Precipitation of Al 6 (FeMn) phase and cubic  -AlFeMnSi phase on (sub)grain boundaries Third minimum: precipitation of phases in the (sub)grain interior