Abstract
An in situ synchrotron experimental study of phase formation dynamics in clad mechanocomposites of Ti-Al systems during high-temperature synthesis was performed. Cladding of the obtained mechanocomposites was carried out with an SiO2 target, with a deposition time of 40 min. The high-temperature synthesis was performed using the thermal explosion method based on a microwave induction heater in the in situ mode on an experimental setup adapted to synchrotron radiation time-resolved diffractometry. The influence of the cladding on the macrokinetic parameters of synthesis in situ was investigated experimentally. It was found that for an ignition temperature Tig = 650 ± 10°C, the maximum synthesis temperatures were in the range Tmax = 1380-1465°C. The characteristic heating speed was 525 K min-1. The sequence and temperature-time interval of phase formation are determined. The formation of the TiAl, TiAl3 and Ti3Al compounds begins at T = 661°C. At Tmax = 1465.6°C, the synthesis product is multiphase, the structures of the formed TiAl3 (content about 70%) and TiAl (content about 25%) have a nonequilibrium state. At the stage of system annealing with T = 1384.9°C, the reaction of the components occurs with the formation of almost monophase TiAl (content of more than 90%); Ti occupies the rest.
Highlights
One of the important problems of modern powder metallurgy is obtaining composite powder materials with a complex of complementary properties for application in the field of gasthermal methods of applying protective coatings, induction surfacing, obtaining structural materials, gas absorbers, etc.One way of obtaining new materials using combustion processes is the method of self-propagating high-temperature synthesis (SHS), which has been used in many studies (Morsi, 2012; Li, 2012; Yi et al, 1992; Li & Sekhar, 1993)
The synthesis was carried out in the thermal explosion mode, switching off the heating source when the maximum temperature was reached, and with system annealing after the chemical reaction was over
The ignition temperatures corresponded to Tig = 650 Æ 10C, and the maximum synthesis temperatures Tmax = 1380–1465C
Summary
One way of obtaining new materials using combustion processes is the method of self-propagating high-temperature synthesis (SHS), which has been used in many studies (Morsi, 2012; Li, 2012; Yi et al, 1992; Li & Sekhar, 1993). The main advantages of this method are the simplicity of the equipment used, low energy consumption, and the short duration of the synthesis process. The process is based on conducting an exothermic chemical reaction of the initial reagents in the combustion form, where the target combustion products are solid chemical compounds (carbides, nitrides, borides, etc.) and materials based on them. A classical SHS is synthesis in the dynamic thermal explosion mode, when the system is under ambient conditions and its temperature changes with time (Merzhanov et al, 1977; Naiborodenko & Itin, 1976).
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