STUDY OF THE INFLUENCE OF SILVER ALLOYING ON THE MICROSTRUCTURE AND PROPERTIES OF MAGNESIUM ALLOY NZ30K FOR IMPLANTS IN OSTEOSYNTHESIS

Abstract

Purpose. Study of the influence of silver alloying of magnesium alloy NZ30K on its mechanical properties for use in the manufacture of biodegradable implants. Research methods. The tensile strength and relative elongation of the samples were determined on a P5 tensile machine at room temperature. The microstructure of the samples was studied using a “Carl Zeiss” optical electron microscope using the “Observer.D1m” software. Samples were used after etching with a reagent containing 1 % nitric acid, 20 % acetic acid, 19 % distilled water, and 60 % ethylene glycol. Fractographic analysis of sample fractures was performed on a JSM-6360LA scanning electron microscope. The phase analysis of the structural components of magnesium alloys was studied using an electron microscope – a microanalyzer with an energy dispersive attachment РEMMA 202М and РЕМ 16I. Research on biocorrosion was carried out by keeping the samples in a solution of gelofusin – an artificial blood substitute for 2, 4, 6 weeks, using a TC-20 MICROmed thermostat. Results. The study showed that silver was a part of the complex alloyed intermetallic phases, which were additional crystallization centers. In this case, the average grain size decreases by almost three times compared to the original alloy. It was found that the optimal set of properties is achieved by the introduction of 0.1 % Ag, while the tensile strength increases by 7.9 % and the relative elongation almost doubles. It was found that the magnesium alloy with silver (0.1 %) slows down biocorrosion processes and helps to maintain a high level of tensile strength (σB = 205 MPa) after 6 weeks of exposure to a solution of helofusine. Thus, silver is a promising material for improving the structure and increasing the mechanical properties of biodegradable magnesium alloy implants. Scientific novelty. The silver content for alloying the NZ30K alloy was determined to be 0.1 % Ag, which forms the optimal ratio of strength and ductility, grain structure refinement, and slowing down biocorrosion processes. Practical value. NZ30K alloy with the addition of 0.1 % silver is promising for use in the manufacture of implants. The studied alloy provides the required level of properties until complete fracture consolidation.