Paper 14.5

Theoretical approach in developing a molar volume database

Lu Xiaogang, Selleby Malin and Sundman Bo

Dept. of Materials Science and Engineering, Royal Institute of Technology,

S – 10044, Stockholm, Sweden

A systematic research on molar volume is in progress to cover the systems available in the Thermo-Calc steel database. The traditional CALPHAD method is used to assess molar volumes and thermal expansions of stable phases. Ab initio calculations are performed to calculate molar volumes at T=0 K, especially for metastable phases. In order to estimate thermal expansions of metastable phases at finite temperatures, a mean-field potential method (MFP) is tested. The work starts with pure elements in the structure of bcc and fcc, some carbides and nitrides are also included.