A new material with a higher melting point than any other known substance has potentially been discovered by scientists.
The alloy, which is a combination of hafnium, carbon and nitrogen, (Hf-N-C) would theoretically only begin to melt at temperatures of more than 4,126°C (7,460°F), which is approximately two thirds of the temperature of the surface of the sun. The current record holder is a combination of hafnium, tantalum and carbon (Hf-Ta-C), which melts at a temperature 3,526°C, so this new material would signify a significant leap forward.
Unfortunately the researchers still need to actually synthesise the material and to test its real-life properties in the laboratory.
The research was undertaken at Brown University, Rhode Island, USA, where scientists used computer modelling to try out different combinations of materials without the expense of actually making them. The researchers calculated the formula for the new alloy by simulating the physical processes that occur at atomic level when a substance melts.
They started by analysing the properties of the Hf-Ta-C material and then looked for other combinations that might maximise these further. Hf-Ta-C combined a high heat of fusion (the energy absorbed or released when the substance transforms from solid to liquid) and low differences in disorder of the atoms, or entropy, as a solid or liquid.
Metals melt when their molecular structures get enough energy to break with the behaviour of the atoms as a liquid, and this also determines the melting point.
The researchers found that the Hf-N-C alloy would absorb similar amounts of energy when it melted but had a smaller difference in the entropy between solid and liquid.
The researchers are now working with the University of California to synthesize the metal, as well as considering its mechanical properties and corrosion resistance.
Suitable applications for such a material would include protective plates on aircraft and in gas turbines.
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