3 .[4] These alloys are highly stable intermetallic compounds . ZrPt 3 , has an enthalpy of formation (ΔH f ) of -124 kcal / mole and a melting point of about 2400 K (3850 ° F ). HfPt 3 has an enthalpy of formation (ΔH f ) of -132 kcal/mole