[2] Very few measurements of melting point in tantalum hafnium carbide have been reported, because of the obvious experimental difficulties at extreme temperatures.

A 1965 study of the TaC-HfC solid solutions at temperatures 2,225–2,275 °C found a minimum in the vaporization rate and thus maximum in the thermal stability for Ta4HfC5.

This rate was comparable to that of tungsten and was weakly dependent on the initial density of the samples, which were sintered from TaC-HfC powder mixtures, also at 2,225–2,275 °C.

In a separate study, Ta4HfC5 was found to have the minimum oxidation rate among the TaC-HfC solid solutions.

[5] In 2015, atomistic simulations predicted that hafnium carbonitride could have a melting point exceeding Ta4Hf1C5 by 200 K.[6] This was later verified by experimental evidence in 2020.