Gary Stofan
Ansys Employee

Hi Helen



Enthalpy is the only quantity that is the integral of a material property.  

The only documention regarding extrapolation and enthalpy is here: 

Considerations for Enthalpy (TBOPT = ENTH)
To ensure correct results, you must define enthalpy over a large enough temperature range to span all computed temperatures during the solution. The TB command does not extrapolate enthalpy values beyond the specified temp range like the MP command does.

If both the TB and MP commands are used to specify enthalpy values, enthalpy values defined via the TB command are used and those defined via the MP command are ignored.