Atomic Pillar-Based Nanoprecipitates Strengthen AlMgSi Alloys
J. H. Chen,*
E. Costan,
M. A. van Huis,
Q. Xu,
H. W. Zandbergen
Atomic-resolution electron microscopy reveals that pillarlike
silicon double columns exist in the hardening nanoprecipitates
of AlMgSi alloys, which vary in structure and composition. Upon
annealing, the Si
2 pillars provide the skeleton for the nanoparticles
to evolve in composition, structure, and morphology. We show
that they begin as tiny nuclei with a composition close to Mg
2Si
2Al
7 and a minimal mismatch with the aluminum matrix. They subsequently
undergo a one-dimensional growth in association with compositional
change, becoming elongated particles. During the evolution toward
the final Mg
5Si
6 particles, the compositional change is accompanied
by a characteristic structural change. Our study explains the
nanoscopic reasons that the alloys make excellent automotive
materials.
* To whom correspondence should be addressed. E-mail: j.h.chen{at}tnw.tudelft.nl
