Influence of Homogenization Heat Treatments on the Mechanical, Structural, Biodegradation, and Cavitation Behavior of Some Alloys in the ZnMg(Fe) System

This paper presents the biodegradation and cavitational erosion behavior of new zinc alloys in the ZnMgFe system. The alloys were heat-treated through homogenization at 300 °C and 400 °C, with maintenance times of 5 and 10 h each. The experimental research consisted of characterizing the structure and mechanical properties of the newly made alloys in different structural states, as well as determining their biodegradation and cavitation behavior. Biodegradability was achieved using laboratory tests in SBF, with different immersion durations (3, 7, 14, 21, or 35 days). The cavitation behavior was assessed by performing tests on a piezoceramic crystal vibrator in compliance with ASTM G32-2016, thus constructing the curves of the erosion velocity MDER(t) and the cumulative average erosion depth MDE(t). The analyses performed on the mechanical properties, microscopic images, and the cavitation parameters MDER and MDEmax (results at the end of the cavitation attack) showed the effect of the heat treatments on the structure and structural resistance to cyclic loadings of the cavitation. The double alloying of zinc with magnesium and iron may increase either the mechanical properties or the corrosion resistance to cavitation and can control the biodegradability of the resulting ZnMgFe alloy. The best heat treatment for improving these properties is homogenization at 400 °C/10 h, which may increase the cavitation erosion of zinc by up to seven times. The experimental results demonstrate that the new alloys from the ZnMgFe system are a good option for manufacturing biodegradable implants with functional in vitro properties.