Guo Yuanyuan; Zhang Shihao; Beyerlein Irene J.; Legut Dominik; Shang Shun-Li; Liu Zhe; Zhang Ruifeng. Synergetic effects of solute and strain in biocompatible Zn-based and Mg-based alloys. Acta Materialia. 2019, vol. 181, s. 423-438. ISSN 1359-6454, eISSN 1873-2453, DOI: https://doi.org/10.1016/j.actamat.2019.09.059.
The article published in Acta Mater. 2019 is devoted to the synergetic effects of solute and strain in biocompatible Zn-based and Mg-based alloys. Zn-based and Mg-based alloys have been considered highly promising biodegradable materials for cardiovascular stent applications due to their excellent biocompatibility and moderate in vitro degradation rates. However, their strength is too poor for use in cardiovascular stents. The strength of these metals can be related to the sizes of the dislocation cores and the threshold stresses needed to activate slip, i.e., the Peierls stress. Using density functional theory (DFT) and an ab initio-informed semi-discrete Peierls-Nabarro model [CPC 2019], we investigated the coupled effect of the solute element and mechanical straining on the stacking fault energy(SFE), basal dislocation core structures and Peierls stresses in both Zn-based and Mg-based alloys. We consider several biocompatible solute elements, Li, Al, Mn, Fe, Cu, Mg and Zn, in the same atomic concentrations. The combined analysis performed here suggests that some elements, like Fe, can potentially enhance strength in both Zn-based and Mg-based alloys, while other elements, like Li, can lead to opposite effects. We show that the effect of solute strengthening and longitudinal straining on SFEs is much stronger for the Zn-based alloys than for the Mg-based alloys. DFT investigations on electronic structure and bond lengths reveal a coupled chemical-mechanical effect of solute and strain on electronic polarization, charge transfer, and bonding strength, which can explain the weak effect on Zn-based alloys and the variable strengthening effect among these solutes. Next, employing our PNADIS code, a generalized scaling diagram is finally drawn for fast evaluation of solid solution strengthening in Zn-based and Mg-based alloys, which provides a general rule in designing novel biocompatible materials [Physical Chemistry Chemical Physics 21, 22629 (2019)].