  In the present study we employed density functional theory calculations to
investigate the mechanical behavior, bonding nature and defect processes of the
new ordered MAX phase Mo2ScAlC2. The mechanical stability of the compound is
verified with its single crystal elastic constants. The new phase Mo2ScAlC2 is
anticipated to be prone to shear along the crystallographic b and c axes, when
a rational force is applied to the crystallographic a axis. The compressibility
along the <001> direction under uniaxial stress is expected to be easier in
Mo2ScAlC2. Additionally, the volume deformation should be easier in Mo2ScAlC2
than in the isostructural Mo2TiAlC2. Mo2ScAlC2 is predicted to behave in a
brittle manner. Due to its higher Debye temperature, Mo2ScAlC2 is expected to
be thermally more conductive than Mo2TiAlC2. The cross-slip pinning procedure
should be significantly easier in Mo2ScAlC2 as compared to Mo2TiAlC2. The new
ordered MAX phase Mo2ScAlC2 has a mixed character of strong covalent and
metallic bonding with limited ionic nature. Both Mo-C and Mo-Al bonds are
expected to be more covalent in Mo2ScAlC2 than those of Mo2TiAlC2. the level of
covalency of Sc-C bond is somewhat low compared to a similar bond Ti-C in
Mo2TiAlC2. Due to its reduced hardness, Mo2ScAlC2 should be softer and more
easily machinable compared to Mo2TiAlC2. Fermi surface topology of the new
compound is formed mainly due to the low-dispersive Mo 4d-like bands. The
intrinsic defect processes reveal that the level of radiation tolerance in
Mo2ScAlC2 is not as high as in other MAX phases such as Ti3AlC2.
