Following zuthal 's suggestion on the Zirconium Diboride thread, here is a model for Hafnium Diboride.
Ceramics.txt Material Hafnium Diboride Elements Hf B ElementCount 1 2 Density_kg__m3 11120 YieldStrength_MPa 985.7 UltimateTensileStrength_MPa 985.7 YoungsModulus_GPa 480 ShearModulus_GPa 212 SpecificHeat_J__kg_K 247.11 MeltingPoint_K 3523 ThermalConductivity_W__m_K 51.6 ThermalExpansion__K 6.92e-6 Resistivity_Ohm_m 9.84e-4 RefractiveIndex Hafnium RoughnessCoefficient 0.5 Turns out all of these properties were out in the open, just waiting to be found. Where more than one value is given on the references, I picked the most precise one, or computed an average of the given values.
DeGregoria, Anthony J. Creep and Oxidation of Hafnium Diboride Based Ultra High Temperature Ceramics at 1500C. Air Force Institute of Technology WPAFB United States, 2015. www.dtic.mil/docs/citations/AD1003573
Christensen, A. N., et al. "Phonon anomalies in transition-metal nitrides: ZrN." Physical Review B 19.11 (1979): 5699.
Aigner, K., et al. "Lattice parameters and thermal expansion of Ti (CxN1− x), Zr (CxN1− x), Hf (CxN1− x) and TiN1− x from 298 to 1473 K as investigated by high-temperature X-ray diffraction." Journal of alloys and compounds 215.1-2 (1994): 121-126.
Adachi, Jun, et al. "Thermal and electrical properties of zirconium nitride." Journal of alloys and compounds 399.1 (2005): 242-244.