Synergic effect of grain refinement and solutionizing on mechanical properties and corrosion behavior of ZE41 Mg alloy aimed for biomedical applications

Abstract Microstructural modification is one of the promising strategies to improve the performance of Mg alloys in developing degradable medical implants. Applying appropriate heat-treatment is also a well proven method to alter the properties of Mg alloys. Recently, ZE41 alloy has gained a special attention as a potential material for structural and biomedical applications. However, achieving grain refinement is challenging in ZE41 Mg alloy by thermomechanical treatments due to its brittle nature at the room temperature. Hence in the present work, ZE41 magnesium (Mg) alloy was subjected to friction stir processing (FSP) followed by solutionizing heat treatment at 335 °C with an objective to investigate the combined effect of FSP and solutionizing on mechanical performance, corrosion resistance and cell response. Significant grain size reduction was observed from 86 ± 3.8 μm to 3.4 ± 1.5 μm after FSP. Post FSP- heat treatment (HT) sample showed grain growth to 6.7 ± 2.2 μm. FSP caused significant reduction in the intermetallic phase (MgZn 2 ). X-ray diffractometry indicated a clear change in the texture of the FSPed alloy. Higher hardness was measured after FSP and FSP+HT compared with base alloy. Increased tensile strength 225 ± 16.3 MPa and 197 ± 10.5 MPa were measured after FSP and FSP+HT compared with base alloy (157 ± 12.8 MPa) without sacrificing the % of elongation. Electrochemical experiments demonstrated lower corrosion current density (5.27 ± 0.44 × 10 −4 μA cm −2 ) for FSP+HT sample compared with the other samples. Immersion studies in simulated body fluid carried out for 3 days also showed decreased weight loss for FSP+HT sample due to the increased biomineralization. Cell viability tests by using African Green Monkey kidney (VERO) cell lines indicated excellent viability for all the samples indicating non-toxicity. The results demonstrate better mechanical properties after FSP alone and improved corrosion properties by combining FSP and HT for ZE41 Mg alloy.