  We study the physical properties of the ionized gas in local disks using the
sample of 38 nearby $\sim10^{8.5-11.2}$M$_\odot$ Star-Forming Main Sequence
(SFMS) galaxies observed so far as part of the MUSE Atlas of Disks (MAD).
Specifically, we use all strong emission lines in the MUSE wavelength range
4650-9300 \AA\ to investigate the resolved ionized gas properties on $\sim$100
pc scales. This spatial resolution enables us to disentangle HII regions from
the Diffuse Ionized Gas (DIG) in the computation of gas metallicities and Star
Formation Rates (SFRs) of star forming regions.
  The gas metallicities generally decrease with radius. The metallicity of the
HII regions is on average $\sim$0.1 dex higher than that of the DIG, but the
metallicity radial gradient in both components is similar. The mean
metallicities within the inner galaxy cores correlate with the total stellar
mass of the galaxies. On our <100 pc scales, we find two correlations
previously reported at kpc scales: a spatially resolved Mass-Metallicity
Relation (RMZR) and a spatially resolved SFMS (RSFMS). We find no secondary
dependency of the RMZR with the SFR density. We find that both resolved
relations have a local origin, as they do not depend on the total stellar mass.
The observational results of this paper are consistent with the inside-out
scenario for the growth of galactic disks.
