how to create a new material that vaporizes
 

Hi,,,
i want to define a new material nitric acid,,,, please help me how can i create a new material that can goes to phase change to nitric acid vapours.... please help.... @ghorrocks please help me,,,,,

I have never created a material like that so I would have to look it up. So that is what I recommend you do - look up the documentation and check the tutorials. Also there are more resources on the ANSYS Customer webpage and ANSYS support has even more stuff available.

there should be something in the library which you can copy and then alter?

If it is a pure substance, and a well defined saturation region you should be able to use a "Homogeneous Binary Mixture" .

Look at that material type, and see if it fits your requirements.