We study the embrittlement of Ni due to the presence of S impurities, considering their effect in the bulk and at grain boundaries (GBs). For bulk Ni, we employ Rice’s theory based on generalized-stacking-fault energetics and the unstable stacking energy criterion. We use first-principles density-functionaltheory calculations to determine the ductility parameter D = γs/γus, the ratio of the sur...

Twinning induced plasticity (TWIP) steels with high manganese percentage (17-35%), are mostly used in automotive bodies. Their microstructure at room temperature is austenitic, and due to the low stacking fault energy, major deformation mechanism in them is twinning inside austenite grains which leads to enhanced mechanical strength in the steel. Due to the important effect of heat treatment pr...

The interfacial energies of twin boundaries and stacking faults in metal magnesium have been calculated using first-principles supercell approach. Four types of twin boundaries and two types of stacking faults are investigated, namely, those due to the (1011) mirror reflection, the (1011) mirror glide, the (1012) mirror reflection, the (1012) mirror glide, the I1 stacking fault, and I2 stacking...

Variable temperature scanning tunneling microscopy experiments reveal that in Ir(111) homoepitaxy islands nucleate and grow both in the regular fcc stacking and in the faulted hcp stacking. Analysis of this effect in dependence on deposition temperature leads to an atomistic model of stacking-fault formation: The large, metastable stacking-fault islands grow by sufficiently fast addition of ada...

It has been proposed that a long-period stacking ordered (LPSO) structure is responsible for the excellent mechanical properties of lightweight alloys of Mg-Y-RE (RE: rare earth elements) system. In this study, the phenomenological simulation model for describing the formation process of the LPSO structure in Mg­Y­Zn system is constructed by means of the phase-field method. The results obtained...

The quantitative characterization of the microstructure evolution in high-Mn steel during deformation is of great importance to understanding its strain-hardening behavior. In the current study, in situ high-energy synchrotron X-ray diffraction was employed to characterize the microstructure evolution in a Fe-17Mn-1.5Al-0.3C steel during a tensile test. The microstructure at different engineeri...

Based on ab initio calculations of both the ABC- and AB-stacked graphites, interlayer potentials (i.e., graphene-graphene interaction) are obtained as a function of the interlayer spacing using a modified Möbius inversion method, and are used to calculate basic physical properties of graphite. Excellent consistency is observed between the calculated and experimental phonon dispersions of AB-sta...