Formation of nanostructures and vacancy behavoir: Their role in the rapid age-hardening in an Al-Cu-Mg alloy

M. MIHARI; C. MACCHI; C. MARIOARA; E. KOBASHAYI; A. SOMOZA

Minami-Osawa Campus, Tokyo Metolopolitan Universty

Congreso; 2017 Annyal Spring Meeting (160th) of the Japan Institute of Metals and Materials; 2017

Japan Institute of Metals and Materials

In age-hardenableAl-Cu-Mg alloys the hardness evolution presents two distinct stages separated bya plateau. The first stage occurs very rapidly (within 60s at 443K) andcontributes to as much as 60% of the total hardness increase. This phenomenonmust be related to nano-sized precipitation in the Al matix. However, an unifiedinterpretation of it is still lacking. This work tries to clarify the role ofthe nanostructures on the rapid hardening and the contribution of vacancies tothe solute transport during the formation of nanoprecipitates. To this aim, theexperimental techniques HAADF-STEM, Positron Annihilation Lifetime Spectroscopy(PALS) and Coincidence Doppler Broadening (CDB) were used.