Effect of interstitial impurities on grain boundary cohesive strength in vanadium

Uncovering the influence of common nonmetallic impurities on the stability and strength of a Σ5 (310) grain boundary in Cu

“…This observation suggests that the impurities with a relatively large atomic size prefer the larger sites while those with a small atomic size prefer the smaller sites. This connection between relative atomic size and the size of the potential segregation interstitial site was also observed by Zhang et al [18] for a Σ3 (111) boundary in V. Fig. 4(b) shows that the energies of all of the grain boundaries with impurities are lower than 0.88 J/m 2 , indicating that the grain boundary energy has been reduced by impurity addition.…”

“…The pristine volumes of the PBP, CTP and BTE are 12.508, 22.033 and 4.742 Å 3 , respectively. We also consider the covalent radius and electronegativity of each impurity because these parameters are related to the size and chemical effects, respectively, associated with a given impurity [18,69]. Grain boundary energy decreases with increasing covalent radius of the impurities and the volumetric deformation of polyhedra.…”

“…The impact of impurities on the mechanical strength of interfaces has also been a topic of many investigations [11,14,17,18,30], which shows that certain impurities can drastically improve the mechanical strength while others cause a detrimental effect. For example, B has been reported to improve the cohesion at grain boundaries in Cu [11], Mo [17] and Fe [36].…”

“…For example, B has been reported to improve the cohesion at grain boundaries in Cu [11], Mo [17] and Fe [36]. Some studies suggest that impurities can form covalent bonds with the host atoms to strengthen interfacial cohesions while others form isotropic polar bonds that cause interfacial embrittlement [17,18,21]. Geng et al [12] showed that the condition for one impurity to be an enhancer was that the atomic size of the impurity must allow it to fit well into the grain boundaries, being neither too small nor too large.…”

“…Grain boundaries are ubiquitous defects in the vast majority of engineering materials, where they play an important role in governing a range of mechanical, functional and kinetic properties [1][2][3][4][5][6]. These properties can be affected by local chemistry, such as the common nonmetallic impurities such as H [7][8][9][10], B [11][12][13][14], C [14][15][16], N [16,17], O [16][17][18], Si [19,20], P [20,21] and S [20,22,23] that are abundant in service environments and conventional processing routes.…”