Effect of heat treatments on the microstructure of an ultrafine-grained Al-Zn-Mg alloy produced by powder metallurgy

Hippolyte Queudet (1, 2, 3) , Lemonnier S. (3) , Barraud E. (3) , Ghanbaja Jaafar (1) , Allain N. (2) , Eric Gaffet (1)

1 IJL - Institut Jean Lamour
2 LEM3 - Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux
3 ISL - Institut franco-allemand de recherches de Saint-Louis

Previous study by Queudet et al. [1] showed that powder metallurgy allows to produce high strength ultrafinegrained(UFG) Al-Zn-Mg alloys which contains both η' and η phases. This present work investigates the effectsof solid solution treatment followed by quenching (W temper) and subsequent ageing to obtain theoretical T6tempered UFG material. TEM analyses revealed the presence of GP zones and metastable η' phase in Wtempered UFG material. Compared to as-fabricated material, quenching conferred to the alloy higher maximumstress of 785 MPa and stabilized plastic flow. Further ageing resulted in over-aged alloy containing the η phase,inducing lower hardness and compressive stress. TEM observations showed that variant η2 which grows from η'is delimited by previous GP-II zones.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Hippolyte Queudet, Lemonnier S., Barraud E., Ghanbaja Jaafar, Allain N., et al.. Effect of heat treatments on the microstructure of an ultrafine-grained Al-Zn-Mg alloy produced by powder metallurgy. Materials Science and Engineering: A, 2017, 685, pp.71-78. ⟨10.1016/j.msea.2016.12.109⟩. ⟨hal-01431184⟩