The influence of Al content on the Fe-C-Al-Si equilibrium phase diagrams

MTDATA is a powerful software package for equilibrium conditions and phase diagram calculations. It can be applied in phase transformation or process simulations depending on the kind of databases they are connected to. The iron-carbon-aluminium-silicon (Fe-C-Al-Si) phase diagrams were calculated using MTDATA software and SGTE databases to determine the phases that are present at various temperature and composition ranges in equilibrium conditions. It was observed that the iron-carbon equilibrium could be modified by addition of aluminum. The austenite region decreased with increasing Al content, and in the case of cast irons containing about 4.88%Al or more, the austenite zone was disappeared. Further results obtained from heat treatment cycles and dilatometry examinations together with optical and electron microscopic investigations showed a good agreement with the calculated phase diagrams for low as well as high (6.16%)Al addition. However, there was a difference between the observations made for 4.88%Al. Experiments conducted on an alloy containing this Al content showed that the austenitic reaction occurred in the alloy, whereas no evidence was found for the -region in the corresponding phase diagram.