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Non-Equilibrium Crystallization of Aluminium alloys with transition metals

ФИО: Hitesh Sharma

Направление: Материаловедение

Научный руководитель: Prof. Vadim Zolotorevskiy

Институт: Институт экотехнологий и инжиниринга

Кафедра: Кафедра Металловедения цветных металлов

Академическая группа: MTM-14-1

The main aim of the project is to study the formation of different metastable phases during non-equilibrium crystallization in Aluminium-transition metal based alloys & the effect of cooling rate on their formation.This will be achieved by investigating the influence of different cooling rates on the prepared samples and performing SEM analysis and XRD.

So far, we prepared three alloys Al-3.5%Mn, Al-4%Mn & Al-4.5%Mn. Alloys were prepared in an electric furnace (Nobertherm) in graphite–chamotte crucibles using 99.99% pure Al and an Al–10 wt% Mn master alloy, which was prepared using 99.9% pure Mn and 99.99% pure Al.

SEM & EDX were used for chemical & microstructure analysis. The alloy of Al–4.5 wt% Mn solidified in the cylinder as described earlier, shows a variation in microstructure as a consequence of differing cooling rates at different locations within the ingot. These can be divided into several zones:Columnar crystals, hypoeutectic zone, eutectic zone & primary crystals. XRD analysis is due & will be performed in coming week.

The Thermo-Calc Databank system v4.0 was used to perform the thermodynamic calculations. The calculations were carried out using the TCAl1, TTAl5 & Cost5 (MISiS user database). Phase diagram for Al-Mn was plotted upto 5% composition.Al6Mn & other phases were suspended to get Al4Mn & Al11Mn4 phases. Both the diagrams were superimposed to compare with each other. This was till now possible only in Cost5 database. Same thing is also being tried in TCAl1 & TTAl5 database. But, still working on them.

The aim of the initial period of the project was, by detailed chemical and structural investigation of the samples, to provide a basis for the comparison of calculated results with already established results for similar alloys by other researchers. The result of these initial studies suggested the formation of several intermediate phases. The variation in microstructure as a consequence of differing cooling rates at different locations within the ingot was also confirmed.

Further investigation is still under process with the same alloys & other different composition are being prepared.