The Effect of Phase Separation on the Mechanical Behavior of the Co-Cr-Cu-Fe-Ni High-Entropy Alloy.

Phase separation phenomena in high-entropy alloys (HEAs) have attracted much attention since their discovery, but little attention has been given to the dynamics of the deformation mechanism of this kind of HEA during uniaxial tension, which limits their widespread and practical utility. In this work, molecular dynamics simulation was used to study the effect of phase separation on the mechanical properties of an HEA under uniaxial tensile loading. Moreover, the associated deformation behavior of the Co-Cr-Cu-Fe-Ni HEA was investigated at the nanoscale.

Plastic Deformation of Pressured Metallic Glass.

Although pressured metallic glass (MG) has been reported in the literature; there are few studies focusing on pressure effects on the structure; dynamics and its plastic deformation. In this paper; we report on and characterize; via molecular dynamics simulation, the structure and dynamics heterogeneity of pressured MGs, and explore a causal link between local structures and plastic deformation mechanism of pressured glass. The results exhibit that the dynamical heterogeneity of metallic liquid is more pronounced at high pressure, while the MGs were less fragile after the release of external pressure, reflected by the non-Gaussian parameter (NGP).

Local melting to design strong and plastically deformable bulk metallic glass composites.

Recently, CuZr-based bulk metallic glass (BMG) composites reinforced by the TRIP (transformation-induced plasticity) effect have been explored in attempt to accomplish an optimal of trade-off between strength and ductility. However, the design of such BMG composites with advanced mechanical properties still remains a big challenge for materials engineering. In this work, we proposed a technique of instantaneously and locally arc-melting BMG plate to artificially induce the precipitation of B2 crystals in the glassy matrix and then to tune mechanical properties.

Correlation between structural heterogeneity and plastic deformation for phase separating FeCu metallic glasses.

Unlike crystalline metals, the plastic deformation of metallic glasses (MGs) involves a competition between disordering and structural relaxation ordering, which is not well understood, yet. Molecular dynamics (MD) simulations were performed to investigate the evolutions of strain localizations, short-range order (SRO) as well as the free volume in the glass during compressive deformation of FeCu MGs with different degrees of phase separation. Our findings indicate that the free volume in the phase separating MGs decreases while the shear strain localizations increase with increasing degree of phase separation.

Vitrification and crystallization of metallic liquid under pressures.

Using molecular dynamics simulation with the embedded atom method, the structural properties of liquid NiAl in a pressure range of 0-20 GPa are investigated with a quenching rate of 2 K ps(-1). Not only is vitrification of liquid at low temperature detected, but also crystallization by change of average atomic volume as a function of temperature. Convincing evidence is presented that the applied pressure strongly affects the vitrification and crystallization of metallic liquid.