Nanocrystalline Al-Mg with extreme strength due to grain boundary doping

Abstract

showing that annealing provides relaxation and hardens the alloys. The dash line represents strengthening from grain size reduction, which is much less significant than that from doping..22

Atomistic Study of the Effect of Magnesium Dopants on the Strength of Nanocrystalline Aluminum

“…Through analyzing different slices of the model, we found that the strong segregation of Mg at Al GB exists in the entire 3D model. This observation is in agreement with the research of Pun et al [2], who also observed that Mg tends to segregate at Al GBs and the segregation amount increases with the increasing annealing temperature and time. The tensile tests were conducted on both the NC pure Al and Al-Mg alloy models at 300K.…”

“…Similar findings can be obtained from the simulation results under these two different applied strain rates. A similar strengthening effect of Mg atoms has been reported in the literature [2,16]. Specifically, Pun et al [2] found that both the strength and hardness of NC Al can be improved by doping Mg atoms.…”

“…Nanocrystalline (NC) materials have been widely used in various applications due to their extraordinary material properties such as high ultimate strength and superior hardness [1,2]. Due to the large volume fraction of high-energy interfacial regions in NC materials, their low thermal stability [3] and low ductility [4] has greatly limited their applications.…”

“…For Al-Mg alloys, researchers have identified that Mg dopants can improve the mechanical properties of materials, including yield strength and strain hardening, through the solid solution strengthening [16,17] and precipitates pinning GBs [18,19]. In addition to those mechanisms, Pun et al [2] found that GB segregation strengthening also contributes to the improved strength and hardness of Al-Mg alloys. Being that Mg atoms have a strong tendency to segregate to GBs, GB segregation strengthening has a larger contribution than solid solution strengthening in Al-Mg alloys.…”

Combined effects of nonmetallic impurities and planned metallic dopants on grain boundary energy and strength

“…Metallic dopants have also been reported to play an important role in altering the mechanical strength of grain boundaries [14,[26][27][28][29][30][31]. For instance, a nanocrystalline Al-Mg alloy was reported to exhibit a yield strength much greater than the upper limit reported for traditional age-hardened Al alloys, with this high strength resulting from Mg segregating to the grain boundaries [28]. Wu et al [29] found that the strengthening effect of metallic dopants on W grain boundaries depended on the type of grain boundary structure and the atomic radius of the added dopant.…”