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Researchers at Lobachevsky University have developed titanium alloys with record strength and corrosion resistance. Structural elements made from such alloys can be used in corrosive environments and at high loads and are cheaper than their commercially available counterparts. 

Titanium alloys are basic materials for manufacturing products that are intended to work in aggressive corrosive environments. That is why titanium alloys are widely used in aircraft, nuclear and petrochemical industries. Another promising application of titanium is in biomedical industry, for instance, for manufacturing prosthetics and implants. "Typically, the task of increasing corrosion resistance of titanium alloys is achieved by complex alloying of titanium alloys with, for example, platinum group metals (ruthenium, palladium and others), which results in a drastic increase in their cost. To increase the strength of titanium alloys, they are subjected to severe plastic deformation, whereby very small submicron grains are formed. However, this approach is not suitable for alloys that work at high temperatures, for example, in aircraft and nuclear power engineering," explains Alexei Nokhrin, Head of the Laboratory for the Diagnosis of Materials at the UNN Physics and Technology Research Institute. 

To produce the alloys, Lobachevsky University scientists used high-speed electric pulse ("spark") plasma sintering, a method for high-speed heating of powders by passing millisecond pulses of high-power electric current through the mold with the specially prepared powder with simultaneous application of pressure. Thanks to this method, Nizhny Novgorod researchers managed to form a homogeneous high-density structure in three types of titanium alloys used in biomedicine (VT1-0 titanium), nuclear power engineering (PT-3V alloy), and aircraft engineering (VT-6 alloy). 

The titanium alloys obtained at the UNN have record hardness and tensile strength values. At the same time, they show a very high resistance to electrochemical and hot-salt corrosion. In particular, the corrosion rate of the new alloys was several times lower than that of commercial alloys produced by conventional methods. Tensile strength and hardness of the titanium alloys were one and a half to two times higher than those of commercial alloys, while the alloys' high ductility was retained. 

Studies performed by the Lobachevsky University team have shown that such properties are due to the diffusion of carbon from the graphite mold into titanium alloys (spontaneous doping) in the process of sintering. Titanium alloy saturation during spark plasma sintering was unusually intense, providing a sharp increase in the characteristics of the alloys. 

Research results were published in the journal Metals, which is listed in the first quartile of Scopus and Web of Science in the field of Metals and Alloys. The research was supported by a grant of the Russian Science Foundation.