Tensile properties of phase interfaces in Mg–Li alloy：A first principles study

Employing density functional theory, we study the tensile and fracture processes of the phase interfaces in Mg–Li binary alloy. The simulation presents the strain–stress relationships, the ideal tensile strengths, and the fracture processes of three phase interfaces. The results show that the α/α and α/β interfaces have larger tensile strength than that of β/β interface. The fractures of both α/α and β/β interfaces are ductile fractures, while the α/β fractures abruptly._Further analyses show that the fracture of the α/β occurs at the interface.     

CN bond orientation in metal carbonitride endofullerenes:A density functional theory study

The geometric and electronic structures of scandium carbonitride endofullerene Sc_3CN@C_(2n)(2 n = 68, 78, 80, 82,and 84) and Sc(Y)NC@C_(76) have been systematically investigated to identify the preferred position of internal C and N atoms by density functional theory(DFT) calculations combined with statistical mechanics treatments. The CN bond orientation can generally be inferred from the molecule stability and electronic configuration. It is found that Sc_3CN@C_(2n) molecules have the most stable structure with C atom locating at the center of Sc3 CN cluster. The CN bond has trivalent form of [CN]~(3-)and connects with adjacent three Sc atoms tightly. However, in Sc(Y)NC@C_(76) with [NC]~-, the N atom always resides in the center of the whole molecule. In addition, the stability of Sc_3CN@C_(2n)has been further compared in terms of the organization of the corresponding molecular energy level. The structural differences between Sc_3CN@C_(2n) and Sc_3NC@C_(2n)are highlighted by their respected infrared spectra.     

First-principles study of the effects of selected interstitial atoms on the generalized stacking fault energies,strength, and ductility of Ni

We analyze the influences of interstitial atoms on the generalized stacking fault energy （GSFE）, strength, and ductility of Ni by first-principles calculations. Surface energies and GSFE curves are calculated for the （112） （111） and / 101） （ 1 1 1） systems. Because of the anisotropy of the single crystal, the addition of interstitials tends to promote the strength of Ni by slipping along the （10T） direction while facilitating plastic deformation by slipping along the （115） direction. There is a different impact on the mechanical behavior of Ni when the interstitials are located in the slip plane. The evaluation of the Rice criterion reveals that the addition of the interstitials H and O increases the brittleness in Ni and promotes the probability of cleavage fracture, while the addition of S and N tends to increase the ductility. Besides, P, H, and S have a negligible effect on the deformation tendency in Ni, while the tendency of partial dislocation is more prominent with the addition of N and O. The addition of interstitial atoms tends to increase the high-energy barrier γmax, thereby the second partial resulting from the dislocation tends to reside and move on to the next layer.