[Back]

R. Fernández Gutiérrez, G. Requena, B. Stauder, E. Maire, A. Isaac:
"3D-CHARACTERIZATION OF AlCu4.5Mg0.3 AND AlCu7 ALLOYS";
Poster: Symposium: "Research at European Neutron and Synchrotron facilities by Austrian researchers", Wien; 11-11-2013 - 11-12-2013.

X-ray microtomography can describe the three dimensional internal microstructure of materials also under the effect of external thermal/mechanical/thermo-mechanical loads [1]. This technique is applied to study the microstructural evolution of A206 (AlCu4.5Mg0.3) and AlCu7 alloys as function of solution treatment (ST) time: 1h, 4h and 16h at 530°C. All samples were overaged 100h at 250°C.

Fig.1 - 3D structure of the aluminides network of the AlCu7: a) as cast condition,
b) after 16h ST at 530°C (ID15-ESRF) (voxel size=(1.1µm)3)

Figure 1 shows the evolution of the volume fraction (Vf) and interconnectivity (volume of biggest aluminide/total aluminide volume) of the aluminides. It was observed that there is a partial dissolution of the phases segregated during casting that stabilizes at <4h ST and the interconnectivity remains over 80% for both alloys. In situ synchrotron tomography is carried during tensile deformation out to characterize the damage mechanisms and evolution. Damage initiation seems to be more likely in the aluminides with a large surface or eutectic areas perpendicular to the loading direction. Cracks propagate along the aluminide network while shrinkage pores  (100 µm)3 play a minor role either for initiation or propagation. This confirms that the interconnectivity of the aluminides network plays a decisive role in the crack propagation process. The alloy after 4 h ST shows an ultimate tensile strength ~ 50 % higher than in as-cast condition as well as an increase of ductility by a factor of ~ 3.The Vf of voids created in the plastic region up to the UTS for the A206 (AC and 4h) is the same, although this is reached at a higher strain after 4 h of ST. This indicates that the microstructure is able to accommodate the same amount of damage in AC and 4 h ST conditions. The fact that the ST alloy shows an increase of strength together with an increase of ductility is a result of the homogeneization of rigid phases that retards the damage formation in the highly interconnected alumide network.

cast Al-Cu alloys, damage evolution, damage mechanisms, synchrotron tomography

http://publik.tuwien.ac.at/files/PubDat_223133.pdf