Investigation of the effect of pressure on some physical parameters and thermoelastic phase transformation of NiAl alloy

Abstract

The Ni-Al alloys which exhibit the thermoelastic phase transformations in the composition range from 60 to 65 atomic percentage of Ni are widely used in the high technology applications. In this study, thermoelastic phase transformations of Ni-37.5 at.% Al alloys at 0, 1 and 2 GPa pressures were investigated by using MD simulation. Physical interactions among atoms in the alloy system were modelled using Sutton-Chen version of the embedded atom method based on many-body interactions. The potential parameters for cross interactions between Ni and Al atoms were estimated by optimising the results obtained from the molecular dynamics simulations. Moreover, the effect of applied pressure on transformation temperatures, enthalpy, entropy and elastic energy of model alloy system were investigated. The obtained result showed that the transformation temperature increased with applied pressure while enthalpy, entropy and elastic energy decreased. The values of the thermodynamical parameters that obtained in this study are in very good agreement with results of experimental studies.

Molecular Dynamics Simulation of a Core−Shell Structured Metallic Nanoparticle

“…However, as an estimation, the nominal volume of the particle can be calculated from a nominal radius, which can be related to the gyration radius through an empirical equation such as R ) R g (5/ 3) 0.5 + R c where R c is the nearest-neighbor atomic distance taken as 2.59 Å. 17 increase process with the increase of temperature. The different diffusion capability of nickel and aluminum atoms is shown by the root-mean-square-distance (RMSD) by tracing atoms at different radial layers (Figure 9).…”

“…Such functional particles can be synthesized by various methods such as cyclic electroplating, continuous combustion, and chemical vapor deposition at relatively low cost. , The thermal-mechanical responses of these particles under heating conditions and the interactions between Ni and Al phases, as well as their consequent structural properties, are essential for their subsequent functional performance. For conventional bulk materials, the Ni−Al phase diagram shows that a nickel-rich solid solution forms at high temperatures ( T ≥ 1000 K), and several phases in the state of intermetallic compounds such as Ni 5 Al 3 , Ni 3 Al, NiAl, Al 3 Ni, and Ni 2 Al may appear at lower temperatures, which are dependent on the temperature and atom concentrations. – Apart from these complexities, Ni−Al intermetallic phase transition at the nanometer scale is expected to have some unique features related to the high ratio of surface atoms and different reaction mechanisms of nanomaterials. The thermal and mechanical properties of nanoparticles can display some unique behavior associated with the size-dependent properties such as melting depression and other low-dimension effects.…”

“…For conventional bulk materials, the Ni-Al phase diagram shows that a nickel-rich solid solution forms at high temperatures (T g 1000 K), and several phases in the state of intermetallic compounds such as Ni 5 Al 3 , Ni 3 Al, NiAl, Al 3 Ni, and Ni 2 Al may appear at lower temperatures, which are dependent on the temperature and atom concentrations. [13][14][15][16][17] Apart from these complexities, Ni-Al intermetallic phase transition at the nanometer scale is expected to have some unique features related to the high ratio of surface atoms and different reaction mechanisms of nanomaterials. The thermal and mechanical properties of nanoparticles can display some unique behavior associated with the size-dependent properties such as melting depression and other low-dimension effects.…”

Aspectos generales acerca de la transformación martensítica

“…Este comportamiento de las martensitas tipo B es conocido como termoelasticidad (Ozgen & Adiguzel, 2004). La magnitud de la histéresis está relacionada con la fuerza impulsora de la transformación, ya que para lazos pequeños es indudable el carácter termoelástico (Kazanc & Tatar, 2008).…”

Structural evaluation and deformation features of interface of joint between nano-crystalline Fe–Ni–Cr alloy and nano-crystalline Ni during creep process

“…The MSD calculation has been carried out in zero load condition because influence of pressure is very less on MSD values for solid state systems[72].…”