Search

The effects of grain size (GS) and distance between twin boundaries (d) on the tensile properties of nanocrystalline (NC) face-centered cubic Cu50Ni50 alloy are studied using the molecular dynamics simulations. The common neighbour analysis, dislocation extraction algorithm, shear strain, and von Mises stress configurations together with the total dislocation length, stress–strain relation, and tensile strength diagrams are presented to investigate the mechanical characteristics of the NC Cu50Ni50 specimens. The results exhibits that the twin boundaries significantly restrict the formation and propagation of the stacking faults. The integral deformation occurs under a combination of displacement, breakage, and self-destruction of the twin boundary along with the contraction and expansion of the grains. The tensile strength increases as the GS and the d increase, which agrees with the inverse Hall-Petch relation. The tensile strength of the conventional NC is higher than that of the twinned NC for each pair of specimens with the same GS. [ABSTRACT FROM AUTHOR]

By using molecular dynamics simulations, the nanoimprinting process was performed to evaluate the mechanical properties and elastic recovery of the CuAgAu metallic glasses. The influences of cooling rate, stamp velocity, temperature, and percentage of the Cu-Ag-Au elements were considered in detail. By changing the imprint conditions, the mechanical responses of the nanocrystalline CuAgAu metallic glasses were mentioned and analyzed. Some important mechanical factors such as imprint force, shear strain, shear transformation zones, the fraction of atoms with high shear strain, and elastic recovery ratio were significantly influenced by changing the simulated conditions and deeply discussed. [ABSTRACT FROM AUTHOR]

• The STZs are mainly formed around the indentation region in the Cu x Ta 100-x layers. • The peak force for the 4-layer ACNLs is much higher than that for the 10-layer ACNLs. • The f 0.05 at the v = 100 m/s is remarkably higher than that in the other cases. • The damage degree of the CuTa/Cu ACNLs increase as the t increases. • As increasing Cu component percentage in the CuTa MGs, the recovery ratio increase. Through molecular dynamics simulations, the nanoindentation with the cylindrical indenter is carried out on the amorphous Cu x Ta 100-x /Cu crystalline nanolaminates (ACNLs). With changing the number of layers, penetration speed, experiment temperature, and composition distribution in the Cu x Ta 100-x layers, the nanoindentation characteristics and recovery capacity of the ACNLs are studied. By inserting the Cu crystal phases into the Cu x Ta 100-x bulk metallic glasses, the formation and development of the shear transformation zones are inhibited, resulting in the plasticity of the Cu x Ta 100-x is enhanced. The typical mechanical factors such as shear strain, von Mises stress, recovery ratio, indentation force, and dislocations of the ACNLs are significantly affected by changing the experiment conditions and profoundly discussed. [ABSTRACT FROM AUTHOR]

• The phase transition from FCC to HCP occurs in the Cu layers. • The atoms with high shear strain concentrate into the diagonal strips that create with the horizontal direction a angle of 45°. • The Cu/CuTa CANMs with more layers are more easily damaged. • As the percentage of Cu element increases, the sample becomes more flexible and softer. • The sample is harder and more brittle as the percentage of Cu element decreases. Through the tensioning process using molecular dynamics simulation method, the mechanistic properties of the Cu/CuTa crystalline/amorphous nanomultilayers (CANMs) are explored. In the Cu layers, the phase transition from FCC to HCP occurs. The embryonic shear bands (ESBs) essentially appear from the crossing positions of the stacking faults and interfaces, after that, grow to establish the shear transformation zones (STZs). The great shear strain atoms concentrate into the diagonal strips that create with the horizontal direction an angle of 45°. The Cu/CuTa CANMs with more layers are more easily damaged. For the cases with the different w 2 values, the f 0.3 value reduces with the increase of the w 2 value. The tensile strength increases with the w 2 increases and the inverse Hall-Petch relation is observed. For the Cu/Cu 10 Ta 90 , Cu/Cu 25 Ta 75 , and Cu/Cu 90 Ta 10 CANMs, the shrinkages are explicit, the formation of the STZs is more obvious than that in the Cu/Cu 50 Ta 50 , Cu/Cu 75 Ta 25 specimen. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) simulations have been employed to simulate the deposition process of Cu and Ni atoms on the Ni (001) substrate with the different compositions in the Cu x Ni 100-x film. Then, the mechanical characteristics of Cu x Ni 100-x /Ni substrate are investigated during the nanoindentation process. The deformation behavior in the nanoindentation process is also investigated when the parameter for velocity, temperature changes. The lattice constant of CuNi alloy increases as Cu content in CuNi alloy rising. In the case of different contents of Cu atoms, the force, hardness of the Cu x Ni 100-x /Ni substrate reduce as increasing the content of Cu. The shear strain and von Mises stress region increase as increasing the temperature and the loading velocity after the loading process. The plastic and elastic deformation of the Cu x Ni 100-x /Ni substrate formed during nanoindentation. The force and hardness of the Cu x Ni 100-x /Ni substrate reduce as increasing the temperature. In addition, with the higher loading speed, the force and hardness values become larger. The dislocation density increases as increasing the indentation depth after the loading process. The specimen of the deposition Cu x Ni 100-x on Ni(001), the specimen Cu x Ni 100-x /Ni substrate and shear strain in the nanoindentation process. Image 1 • As Cu content in Cu x Ni 100-x film rises the lattice constant of deposited CuNi film increases. • The high-shear strain area of the Cu x Ni 100-x /Ni substrate propagates to interface in the indentation process. • The force, hardness of Cu x Ni 100-x /Ni substrate decreases as increasing the content Cu and temperature. • The force, hardness of Cu 40 Ni 60 /Ni substrate increases as increasing the loading velocity. • The dislocations density increases as increasing the temperature and the loading velocity. [ABSTRACT FROM AUTHOR]