  212 MAX phase borides are new additions to the MAX phase family with enhanced
thermo-mechanical properties. In this article, first-principles calculations
have been carried out to explore the mechanical properties, Vickers hardness,
elastic anisotropy, thermal properties, and optical properties of predicted
thermodynamically stable MAX compounds Hf2AB2 (A = In, Sn). The structural
properties are compared with the available data to assess the validity of
calculations. The mechanical stability of Hf2AB2 (A = In, Sn) compounds is
established with the help of the computed stiffness constants (Cij). The
possible reason for enhanced mechanical properties and Vickers hardness of
Hf2SnB2 is explained based on the analysis of bonding strength, followed by the
electronic density of states. Higher mechanical strength and Vickers hardness
of Hf2AB2 (A = In, Sn) compared to Hf2AC (A = In, Sn) are also indicated in the
light of charge density mapping. The values of Pugh ratio, Poissons ratio and
Cauchy pressure predict brittle character of the studied compounds. Besides,
the anisotropic nature of the titled borides is investigated by 2D and 3D plots
of elastic moduli along with some well established anisotropy indices. Thermal
properties were investigated by calculating the Debye temperature, minimum
thermal conductivity, Gr\"uneisen parameter, and melting temperature. The
thermal properties of Hf2AB2 (A = In, Sn) are also superior to Hf2AC (A = In,
Sn). The optical constants such as real and imaginary parts of the dielectric
function, refractive index, extinction coefficient, absorption coefficient,
photoconductivity, reflectivity, and loss function are investigated.
