MTDATA – Phase Diagram Software from the National Physical Laboratory









Virtual Measurement System for Al Alloys

Obtaining reliable values for a particular material property that affects your process is a continuing problem for plant engineers, materials scientists and researchers working with aluminium alloys. Often the particular data you need are not quoted or it is seen as unreliable or no data exists for the system of interest. With this in mind NPL has developed the Virtual Measurement System for Aluminium Alloys, a software tool which aims to overcome these problems by making predictions of key thermophysical properties. It has been developed by the NPL Materials Centre in conjunction with industrialists and is based on a careful analysis of experimental data measured either at NPL or reported in the literature.

Key Features

Virtual Measurement System Main InterfaceThe first NPL Virtual Measurement System available for solidification of aluminium alloys provides reliable predictions of the key thermophysical properties simply and efficiently. You only need to input the composition and temperature range of interest. Other key features include:

  • The complex calculations require no user intervention nor prior knowledge of the basis behind the models
  • The software has already been successfully assessed by engineers to understand and improve a variety of industrial processes
  • Results can be exported easily into an ExcelTM spreadsheet allowing you to analyse the results further or to combine them with your own data
  • Choose the accuracy of the calculation depending on whether you want a quick look or a more precise value

Virtual Measurement System Results Screen


The elements currently covered by the aluminium system are:

  • Aluminium - (at least 60 wt%)
  • Silicon - (max 30 wt%)
  • Iron - (max 4 wt%)
  • Magnesium - (max 15 wt%)
  • Manganese - (max 3 wt%)
  • Copper - (max 15 wt%)
  • Zinc - (max 11 wt%)

The composition limits given are imposed by the program in order to simplify the calculations. They have been chosen to allow the calculations to cover current commercial alumiuium alloy compositions. If you require a prediction from a composition outside these limits then please contact NPL (see below).

To aid the user, the compositions for some of the more commonly used alloys are included and it is easy to modify these to correspond to the chemical compositions of your particular alloy. Some allowance for kinetics can be made due to the inclusion of the Scheil solidification model.

The program enables you to predict:

  • which phases solidify from the melt
  • mass fraction of solid during solidification
  • enthalpy and specific heat of solid and liquid and enthalpy of fusion
  • density of the liquid and solid
  • thermal conductivity of the liquid and solid

Basis of the models

Underlying all the calculations is one of the world's foremost thermochemical modelling packages, MTDATA, developed at NPL for the calculation of phase equilibria from thermodynamic data and a database covering the main components in aluminium alloys. The density (volume) is calculated thermodynamically using a unique database. The thermal conductivity is estimated using the Wiedermann-Franz-Lorenz rule for the liquid and a simplistic model for the solid.

Predictions made using the system have been compared with both literature data and measurements made at NPL. Full details of the explanation of the basis of the models used in the Virtual Measurement System will be provided with the programme.


If you are interested in extending the system to more elements, or predicting other properties NPL may be able to customize the programme to your requirements. Please contact us to discuss your technical requirements.

Further Information

For more information or a quotation please contact Jim Robinson or Hugh Davies

Alternatively go to the NPL e-Store to buy online and download - Virtual Measurement System for Al Alloys Go to e-Store


Updated 12 May 2008