Graphical abstract

As revealed by studies, in the process of high-pressure torsion of hard or work-hardenable metals and alloys, including bulk metallic glasses, the actual produced strain is much smaller than the expected one. The authors proposed a new technique called “accumulative high-pressure torsion” for producing high strains in hard materials, including bulk metallic glasses.

This paper investigates the mechanical properties at elevated operation temperatures of the Ti alloy VT8M-1(Ti-5.3Al-4.0Mo-1.2Zr-1.3Sn-0.2Si) in the coarse-grained (CG) and ultrafine-grained (UFG) states. The duplex UFG structure was produced by rotary swaging at a temperature of 750 °C. The UFG state was studied in terms of thermal stability during annealing at temperatures 500, 550, 600, 700 °C for a period of 1 hour. It was demonstrated that the recrystallization processes in the UFG structure start after annealing at 550 °C and above. We performed tensile mechanical tests at such temperatures. In a range of 300-450 °C, the ultimate tensile strength of the UFG alloy was stably above that of the CG alloy. Mechanical tests at 500 and 550 °C revealed a more significant decrease in the ultimate tensile strength of the UFG alloy as compared to the CG alloy, conditioned by the intensification of the recovery and recrystallization processes at these temperatures.

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The use of titanium shape memory alloy Ti-18Zr-15Nb with promising coatings for the manufacture of medical implants is considered. In this paper, we examined plasma electrolytic oxidation (PEO) in a pulsed bipolar mode with different frequencies to protect the surface from the aggressive environment of the human body.. Two frequencies of 300 and 1000 Hz were used. The results of SEM, EDS, XRD analysis, and electrochemical tests of the coatings were discussed. As a result of comparison, it was shown that carrying out the PEO process at 1000 Hz provides the formation of a more uniform coating with higher quality than the coating obtained at 300 Hz.