Bioinert metals are used for medical implants and in some industrial applications. This study was performed to detect and analyze peculiarities that appear in the temperature distributions during quasi-static tensile testing of bioinert alloys. These alloys include VT1-0 titanium, Zr-1%Nb and Ti-45%Nb in both coarse-grain (CG) and ultrafine-grain (UFG) states. The crystal structure, as well as the crystal domain and grain sizes of these alloys in the UFG state, may be different from the CG versions and identifying the thermal signatures that occur during their deformation and fracture is of interest, as it may lead to an understanding of physical processes that occur during loading. By comparing the surface temperature distributions of specimens undergoing deformation under tensile loading to the distributions at maximum temperatures it was found that the observed differences depend on the alloy type, the alloy structural state and the thermal properties of structural defects in the specimen. Macro-defects were found in some specimens of VT1-0 titanium, Zr-1Nb and Ti-45Nb alloys in both the CG and UFG states. The average tensile strength of specimens containing defects was lower than that of specimens with no defects. Infrared thermography documents change in the thermal patterns of specimens as they are deformed under tensile loading and when the load stops changing or the specimen breaks.

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Fatigue tests were carried out on samples of titanium VT1−0 and zirconium alloy Zr−1 wt % Nb in the ultrafine-grained, fine-grained and coarse-grained states in a gigacycle fatigue regime. It was found that the formation of an ultrafine-grained structure led to an increase in the fatigue limit in the gigacyclic region (10 9 cycles) by 1.3 times for titanium and 1.7 times for zirconium alloy when compared to the fine-grained and coarse-grained states. An evolution of the temperature field for titanium and zirconium alloy samples in various structural states in the process of cyclic loading was studied by the method of infrared thermography. It was shown that the process of cyclic deformation in all types of structural states was accompanied by an initiation and expansion of a heat source in a local volume of samples which has a significant impact on the fatigue strength. The increment of the maximum temperature on the surface of ultrafine-grained samples of titanium VT1−0 and zirconium alloy Zr−1 wt % Nb is significantly lower than that for the fine-grained and coarse-grained states. This fact indicates a qualitative change in the mechanism of energy dissipation which is associated with characteristic features of the ultrafine-grained state. When comparing the dynamics of thermal fields for the titanium and zirconium alloy samples in coarse-grained, fine-grained and ultrafine-grained states, it was found that the energy dissipation zone covered a considerable volume of the sample in the process of fatigue tests in case of ultrafine-grained state, whereas in case of coarse-grained and fine-grained states the growth of thermal energy was localized in the gauge area of the sample.