MTDATA – Phase Diagram Software from the National Physical Laboratory









MTDATA Demonstration : Overview


Users with a problem to solve using MTDATA will normally take the following steps:

  • Retrieve data for the system of interest.
  • Select the type of calculation desired.
  • Specify amounts and conditions.
  • Initiate the calculation.
  • Plot or print the results.

The following examples provide some snapshots of what MTDATA can do.


Combusted materials including their impurities create the environment in which advanced materials perform. An understanding of that environment and its interaction with materials is vital to their development and application.

For example, if salt and sulphur are present, sodium sulphate can deposit and dissolve the protective oxide layer on alloys or ceramics. The diagram below shows the conditions under which sodium sulphate deposits are calculated.


Salt mixtures

In practice the salts are mixtures. This lowers the liquidus temperature and increases their aggressiveness in corrosion. Molten salt systems are also of great commercial importance in fuel cells, lamps and in refining metals.

The diagram below shows how the liquidus varies in the system NaCl-KCl-Na2SO4-K2SO4.

Oxide systems

Oxides, especially those of calcium, magnesium, iron, aluminium, and silicon are of enormous importance in pyrometallurgical extraction, construction materials, ceramics and glass. NPL, with support from Mineral Industry Research Organisation, has been undertaking the generation of a database for oxides, with the aim of predicting the behaviour of glasses, ceramics and refractories under various environments and the partition of components between the metal, slag and gas phases as required for the design and operation of pyrometallurgical plant.

The diagram below is a section from one of the key systems: CaO-Al2O3-SiO2.


Process simulation

The principle of calculation of phase equilibria in multicomponent systems using as a basis critically assessed thermodynamic data for the subsystems of the phases involved, is particularly well developed for alloy systems. The same principle can now be applied to dynamic processes by linking MTDATA to software for kinetic phenomena.

The diagram below provides a simple example of a Scheil plot which shows how the composition of the liquid in the Fe-Cr-Ni system changes as solidification proceeds. Segregation of components has an important influence on microstructure.


Updated 12 May 2008