NPL has developed MTDATA software specifically designed to model thermophysical data and calculate phase diagrams The approach is, in essence materials chemistry by computer applied to the particular interests of the industry. The properties which can be studied as a function of temperature are:

• Variation of heat capacity and enthalpy with temperature
• Fraction solid and fraction liquid during solidification
• Nature and composition of the solid phases formed.

MTDATA is capable of making prediction either under equilibrium conditions or by assuming that diffusion within the solid phases is negligible compared with that within the liquid. Comparison between the predicted and experimental values gives confidence for the results of particular classes of alloys both in the experimental technique and in the predictive approach. Particular advantages of this predictive approach are:

• Calculations can be used to explore the change in properties across the specification of a given alloy. A booklet describing the MTDATA approach, together with a demonstration disc, is available on request.
• Calculations are quick and reliable once the relevant data are available.

For more information, please contact Jim Robinson