Pressure Effects on the Structural Evolution of Monatomic Metallic Liquid Hafnium
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Tarih
2018
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info:eu-repo/semantics/openAccess
Özet
Structural evolution of monatomic metallic liquid hafnium under high pressures of 0-50 GPa has been investigatedby molecular dynamics (MD) simulations using the tight-binding (TB) many body potentials during rapidlysolidified processes. The structural evolution and glass formation (GF) process have been analyzed by using pairdistribution functions (PDF), Wendt-Abraham (RWA) parameter, Honeycutt-Andersen (HA) and Voronoitessellation (VT) methods. When the system has been cooled with a cooling rate of 2x1013 Ks-1, the glassy statesare obtained for P?40 GPa pressures and the crystalline phase is obtained at P=50 GPa pressure. The number offace-centered cubic (fcc) and hexagonal close-packed (hcp) (fcc + hcp) type bonded pairs increase dramatically,while the number of perfect icosahedra, distorted icosahedra and body-centered cubic (bcc) type bonded pairsdecreases with increasing of pressure. This is an indication that the solidification process of the system begins withnucleation in the liquid and that nucleation growth with increasing pressure continues to develop. The results showthat the variation of local atomic bonded pairs is of great importance to understand the glass formation andcrystallization process. However, it has been observed that the applied high pressure (HP) weakened icosahedralorder and increased the fraction of other clusters in glassy hafnium at low temperatures. Furthermore, it has beenobserved that all glass transition temperatures (Tg), main bond types and main base clusters change with increasingpressure.
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Kaynak
Bitlis Eren Üniversitesi Fen Bilimleri Dergisi
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Cilt
7
Sayı
1
