SHS Compactification of Titanium Nickelide: Mechanical Activation, Combustion, Structure, and Properties
Yu. V. Bogatov, V. A. Shcherbakov, I. I. Chuev
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, Russia
Keywords: SHS compaction, mechanical activation, titanium nickelide, combustion rate and temperature, phase composition, microstructure
Abstract
The conducted research relates to the works on obtaining consolidated materials by the method of self-propagating high-temperature synthesis (SHS) with subsequent compaction of hot products (SHS compaction). By the method of SHS compaction of mechanically activated mixtures of Ni and Ti powders, pore-free samples of titanium nickelide with a diameter of 70 mm and a thickness of 8 mm were obtained. The combustion of the Ni + Ti mixture was carried out in a reaction mold without preliminary heating and a protective environment. The effect of mechanical activation in a ball mill on the characteristics of the mixtures and the combustion parameters was studied. The analysis of the microstructural characteristics showed that an increase in the reactivity of Ni + Ti MA mixtures and the implementation of exothermic interaction in the SHS mode are due to a decrease in the crystallite size in Ni particles, an increase in the dislocation density in them and the formation of composite Ti-Ni particles. The maximum combustion temperature of the reaction mixture is 1150 °C, the average combustion velocity is 3.5 cm/s. The main phases of the synthesized alloy are Ti2Ni, NiTi and Ni3Ti. The compressive strength of the samples is 1350 MPa, the Vickers microhardness is 11.1±1.2 GPa.
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