Abstract
Magnesium alloys are promising materials for the fabrication of bioresorbable structures for medical applications. However, the lack of a unified methodological approach to selecting test conditions and the variety of saline solutions used significantly complicate the comparison of published data. Another important issue is the pursuit of simultaneously high mechanical and corrosion properties of magnesium alloys. In this study, using ZK60 and AZ31 alloys as model examples, which possess relatively high mechanical properties but low corrosion resistance (ZK60) and vice versa (AZ31), the microstructure, mechanical, and corrosion-fatigue characteristics of the materials are investigated under a symmetric loading cycle (R = −1) in air and in three of the most common corrosive environments: 0.9 % NaCl, Hanks and PBS solutions. In all cases, a corrosive environment significantly reduces the durability of specimens due to the formation of localized corrosion damage on the surface, which act as strong stress concentrators and facilitate crack initiation. Reduction in fatigue properties occurs according to the following sequence: PBS → Hanks → 0.9 % NaCl, with the fatigue life in Hanks and PBS solutions exceeding that in NaCl by 2 – 4 and 4 – 6 times, respectively. The fatigue limit in these environments may not correlate with statically measured corrosion, as high initial mechanical properties can temporarily compensate for the higher corrosion rate. The obtained experimental data demonstrate that understanding the fatigue limit and corrosion rate enables a comprehensive assessment of the geometric parameters and thickness of components, taking into account force or time loading, paving the way for the individual selection of alloys for the specific service life of a medical implant.
Funding
1. State assignment project - FEMR-2024-0002