Mechanical Properties of Magnetron Sputtered Free Standing Mg-Ag Alloy Films

Abstract

Magnesium based alloys gained great interest for medical biodegradable applications. Limitations arise from high corrosion rates and mechanical properties of the Mg based alloys. In recent work it was shown that the corrosion rate of a precipitate free Mg-6Ag thin film can be reduced by a factor of three compared to pure sputtered Mg. As Mg-6Ag combines the very promising corrosion results with a potential therapeutically use of Ag ions, the investigation of their mechanical properties is needed for a full characterization of Mg-Ag alloys as biodegradable material. In this work the Ag content was varied from 2 to 10 wt%. The investigated thin film samples were dog-bone shaped samples with a thickness of 20 µm. The samples were fabricated by a combination of UV lithography, sacrificial layer technique and magnetron sputtering. The mechanical properties were determined using uniaxial tensile test. Compared to pure Mg samples fabricated by the same processing route the yield strength is approximately doubled for Ag containing samples. For films with a Ag concentration up to 8 wt% the elongation at fracture reaches a value of ∼7%. Further increase of the Ag concentration leads to lower elongation at fracture. Thus, especially due to the low corrosion rate, Mg-6Ag shows the optimum of all investigated alloys, with a yield strength of ∼310 MPa and an elongation at fracture of ∼6%.

Biodegradable, flexible silicon nanomembrane-based NOx gas sensor system with record-high performance for transient environmental monitors and medical implants

“…S11. When the total stretchability of the system is defined at a level, where the maximum principal strain of half the width of one section exceeded the fracture strain of the metal interconnect (9-10% for Mg thin film 39,40 ), as in a previous report 37 , the obtained total stretchability of~40% corresponded well to the experimental value of Fig. 3e.…”

Efficient numerical strategies for an implicit volume fraction transfer scheme for single crystal plasticity including twinning and secondary plasticity on the example of magnesium

“…Finally, the possibility to incorporate solid solution hardening into the model was investigated. Tensile test simulations of polycrystalline sputter deposited magnesium‐silver (Mg‐Ag) thin films that exhibit a columnar grain structure and c‐axis alignment were compared to experimental data by Reference 37. As depicted in Figure 7, for pure magnesium the grain structure is approximated by a quasi two‐dimensional (2D) Voronoi‐structure with 200 grains and a mesh consisting of $$$ 316\times 316\times 1 $$$ elements.…”

“…The model is explained in detail and a new solution algorithm for the nonlinear equation system, reducing the plastic deformation on 13 $$$ \times $$$ 18 slip systems and 12 twinning systems (in total 246 unknowns) to 31 unknowns, is presented. Finally, FEM simulation results are compared to experimental compression of single‐crystal and polycrystal results from Kelley and Hosford 36 and polycrystal tension experiments from Jessen et al 37 …”