J. Phys. Colloques
Volume 48, Numéro C3, Septembre 19874th International Aluminium Lithium Conference
|Page(s)||C3-557 - C3-563|
J. Phys. Colloques 48 (1987) C3-557-C3-563
ACOUSTIC EMISSION DURING DEFORMATION OF Al-Li ALLOYSM. FURUKAWA1, Y. MIURA2 et M. NEMOTO2
1 Faculty of Education, Department of Technology, Fukuoka University of Education, Munakata, 811-41, Japan
2 Faculty of Engineering, Department of Metallurgy, Kyushu University, Fukuoka, 812, Japan
The relationship between tensile elongation and acoustic emission (AE) detected during compressive deformation of Al-Li and Al-Li-Zr alloys has been investigated for a range of microstructure. For comparison, AE measurements have been carried out for Al-Cu and commercial 7050 alloys. In the polycrystalline binary Al-Li alloys, the most pronounced AE was detected in the underaged condition during the onset of plastic deformation. The AE increased with increasing Li content, attained a maximum emission at 3-4.5% Li and decreased by further addition over the maximum solid solubility of Li in Al. The strong burst AE was detected in the Al-Li single crystal with a multi-slip orientation. In contrast, the AE in the sample with a single slip orientation was appreciably small. The AE in the binary Al-Li alloys was much greater than those in the Al-Cu and 7050 alloys. The addition of 0.1-0.5 % Zr to the polycrystalline Al-Li alloy greatly lowered the AE and improved the ductility appreciably. The proposed sources of burst AE in the binary Al-Li alloys during the onset of plastic deformation are the formation of coarse slip bands induced by shearing of L12-ordered coherent δ'-particles and the intersection of slip bands with each other ana with grain boundaries. The intersection of coarse slip bands and weak grain boundaries are considered to be responsible to the loss of ductility in the binary Al-Li alloys. Transmission electron microscope observations of the interaction between deformation induced dislocations and precipitate particles revealed that the dispersion of fine metastable Al3Zr particles changed the mode of dislocation glide through the introduction of the Orowan bypass process.