Calculation of driving force and local order to predict the favored and optimized compositions for Mg-Cu-Ni metallic glass formation

et al. 2019

Materials

Ab initio calculations were conducted to assist the construction of the n-body potential of the Ti-Nb-Al ternary metal system. Applying the constructed Ti-Nb-Al interatomic potential, molecular dynamics and Monte Carlo simulations were performed to predict a quadrilateral composition region, within which metallic glass was energetically favored to be formed. In addition, the amorphous driving force of those predicted possible glassy alloys was derived and an optimized composition around Ti15Nb45Al40 was pinpointed, implying that this alloy was easier to be obtained. The atomic structure of Ti-Nb-Al metallic glasses was identified by short-, medium-, and extended-range analysis/calculations, and their hierarchical structures were responsible to the formation ability and unique properties in many aspects.

Section: Metallic Glass Formation Of Ti-nb-al Systemmentioning

confidence: 99%

Atomic-Approach to Predict the Energetically Favored Composition Region and to Characterize the Short-, Medium-, and Extended-Range Structures of the Ti-Nb-Al Ternary Metallic Glasses

Cai

et al. 2019

Materials

Structural skeleton of preferentially interpenetrated clusters and correlation with shear localization in Mg–Cu–Ni ternary metallic glasses

Wang

Phys. Chem. Chem. Phys.

et al. 2014

Self Cite

Inherent hierarchical structure and its effect on shear localization were clarified for ternary Mg-Cu-Ni metallic glasses via molecular dynamics studies based on a newly constructed n-body potential for the system. Assisted by a proposed index to detect the medium-range correlation heterogeneity, it was found that the Cu/Ni-centered icosahedra and specific Mg-centered clusters exhibit a strong preference to interconnect, leading to the formation, over an extended scale, of a percolated network that serves as structural skeleton in the glassy matrix. In constituting the skeleton network, the clusters mainly integrate in an interpenetrating mode, while the noninterpenetrating linkages provide additional reinforcements, jointly consolidating the structural and energetic stability of the skeleton. Furthermore, by monitoring the structural evolution upon compressive deformation, it was revealed that the gradual collapse of the skeleton network is intimately correlated to the mechanical response of metallic glasses and acts as a structural signature of the initiation and propagation of shear bands.

Atomistic study of chemical effect on local structure in Mg-based metallic glasses

Wang

et al. 2015

RSC Adv.

Self Cite

By applying a recently constructed interatomic potential, molecular dynamics (MD) simulations were performed to investigate the structural origin of chemical effects in Mg-Cu-Ni ternary metallic glasses.The detailed evolution of local atomic structure in a series of Mg x (Cu 42.5 Ni 57.5 ) 100Àx (x ¼ 40-80) metallic glasses was tracked and comprehensively characterized by the pair correlation function, Voronoi tessellation, Honeycutt-Andersen bond pair and local chemistry analyses. Remarkable topological shortrange orders (SROs) were found in Mg-Cu-Ni metallic glasses, with the characteristic motifs being icosahedra. The degree of icosahedral ordering varies distinctly with the alloy composition and is intimately correlated with the phase stability of metallic glasses. In contrast to the long-term understanding that five-fold bond pairs are a direct indication of icosahedral ordering, it was revealed that bond pairs are actually insensitive to the composition, and whether icosahedral ordering is preferred or not, fragmented pentagonal bipyramids are always populated. Furthermore, it was indicated that multiple chemical interactions among constituent atoms do result in chemical SROs in Mg-Cu-Ni metallic glasses, which are characterized by enriched Mg atoms in neighboring shells than expected from the nominal composition. The atomic-scale topological or chemical heterogeneity helps tune the local environments in Mg-Cu-Ni metallic glasses to achieve efficient packing and energy minimization for various compositions. Fig. 2 Total pair correlation functions, g(r), for Mg x (Cu 42.5 Ni 57.5 ) 100Àx (x ¼ 40, 50, 60, 70 and 80) MGs. To further reveal the fine structure, the partial pair correlation functions, g AB (r), that contribute to the total g(r) for MG with x ¼ 80 are also displayed. The blue dashed line is g AB (r) for Mg-Mg, the dashed/dotted line is for Mg-Cu, and the dotted line is for Mg-Ni. The g AB (r) for Cu-Cu, Cu-Ni, and Ni-Ni are not shown here due to their minor contributions.This journal is