2017 №02 (06) DOI of Article
2017 №02 (08)

Electrometallurgy Today 2017 #02
Electrometallurgy today, 2017, #2, 45-52 pages
Plotting of calculation thermokinetic diagrams of anizothermal transformations of titanium alloys on aluminides base
V.A. Kostin, G.M. Grigorenko, S.G. Grigorenko
E.O. Paton Electric Welding Institute, NASU. 11 Kazimir Malevich Str., 03680, Kiev, Ukraine. E-mail: office@paton.kiev.ua
Aluminides and alloys on their base are the promising high-strength and scale-resistant materials, demanded for critical equipment and components, in particular in shipbuilding, aerospace industry. The main method of producing the required complex of mechanical properties of intermetallic alloys is their thermomechanical treatment, the parameters of which can be obtained on the base of plotting the thermokinetic diagrams of anisothermal transformations of intermetallic alloys of Ti–Al system. The obtaining of experimental thermokinetic diagrams of intermetallic alloys is quite difficult. The aim of the present work was in plotting of a calculation thermokinetic diagram of anisothermal transformations of intermetallic titanium alloy on the titanium aluminide base. The calculation method was based on using the theory of multi-component alloys and thermodynamic modeling using the CALPHAD methodology. To solve the problem of prediction of temperatures of phase transformations in intermetallics of Ti–Al system, the method of a regression analysis was used. The procedure was developed, with the help of which the thermokinetic diagram of formation of titanium aluminide Ti3Al was plotted. The equations of regression for determination of temperatures of beginning the phase transformations on the diagram of state of the Ti–Al system were suggested. The effect of aluminium content in intermetallics Ti3Al on the temperature of beginning the intermetallic formation was determined. It is shown that with increase in aluminium content in intermetallic Ti3Al from 10 up to 29 at.% the temperature of beginning the β-Ti>Ti3Al transformation is increased from 520 up to 1170 oC. The further increase in aluminium content in intermetallic from 29 up to 40 at.% leads to a negligible reduction in initial temperature of transformation to 1140 oC. The developed method can be used for the modeling of thermokinetic diagrams of anisothermal transformations in complex titanium alloys, Ref. 19, Table 1, Figures 5.
Keywords: titanium alloys; intermetallics; titanium aluminides; phase transformations; Gleeble 3800; regression analysis


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