  Both simulations and observations suggest that the disk assembly of galaxies
is governed by the interplay between coplanar gas inflow, ex-planar gas outflow
and in-situ star formation on the disk, known as the leaky accretion disk. This
scenario predicts a strong connection between radial distributions of star
formation and chemical abundances. The Milky Way, being the sole galaxy where
we can reliably measure star formation histories and the corresponding
temporally-resolved chemical abundances with individual stars, provides a
unique opportunity to scrutinize this scenario. Based on the recent large
spectroscopic and photometric surveys of Milky Way stars, we obtain the radial
profiles of magnesium abundance ([Mg/H]) and star formation rate (SFR) surface
density at different lookback time. We find the radial profiles of [Mg/H] can
be well-reproduced using the leaky accretion disk model with only two free
parameters for stars formed within 4 Gyr, as well as the flattening at large
radii of metallicity profiles traced by HII regions and Cepheids. Furthermore,
the constraint effective yield of the Milky Way and nearby galaxies show broad
consistency with the theoretical predictions from stellar chemical evolution
model with a mass-loading factor of 0-2. These results support that the recent
assembly of the Milky Way adheres to the leaky accretion disk scenario,
bridging the disk formation of our home galaxy to the big picture of disk
formation in the Universe.
