Thermodynamic Modeling of the Undercooled Liquid in the Ni–Zr System

Abstract

Using thermodynamic data obtained over a wide range of temperatures, a thermodynamic assessment of the Ni-Zr system was carried out. The associated solution model was applied to describe the short range ordering in the liquid, and the glass transition was treated as a second order transition, using the Hillert-Jarl functions. The driving force of crystallization, and the time-temperature-transformation (TTT) curves were estimated from the optimized parameter set, and compared with experimental data and the results of previous thermodynamic assessments. Taking into account the low temperature thermodynamic data, the calculated driving force was found to have decreased compared to the previous assessments. Consequently, the nose of the TTT curve was shifted to higher times.

Estimation of the glass forming ability of the Ni–Zr and the Cu–Zr alloys

“…Using those thermodynamic databases, several attempts have been made to estimate the GFA such as the driving force for crystallization from the undercooled liquid, and the critical cooling rate for the amorphous formation [5][6][7]. Recently, the authors have shown in the Cu-Zr binary systems [8] that those thermodynamic properties at low temperatures, which are missing in previous assessments of those binary systems [9][10][11], are indispensable for accurate estimation of the driving forces and the critical cooling rates.…”

Local atomic arrangements and their topology in Ni–Zr and Cu–Zr glassy and crystalline alloys

“…Nickel and copper are neighbours in the periodic table and have many similarities; for example, they both have the face-centred cubic (cubic close-packed) crystal structure, very similar densities, atomic sizes, and electronegativities [1]. Upon alloying with zirconium, nickel forms eight and copper forms six stable intermetallic compounds with complicated crystal structures, giving complex Ni-Zr [2] and Cu-Zr structural models for Cu-Zr glasses and found that they are composed of interconnected clusters with icosahedral and dodecahedral symmetry. Mattern et al [31] studied Cu-Zr glasses by reverse Monte-Carlo (RMC) simulation and analysed the model configurations.…”

Experimental study of the phase equilibria of the Ni – Zr system

“…[17].The discrepanciesbetween the calculated and the measured are above5 0 8 C.Though the eutectictemperature,a bout 1003 8 C, calculated byAbee tal. [18]seemsclosetothe measured data, the calculated melting points of NiZrand NiZr 2 aremuchlowerthanthe experimentaldata.Thoseresearchers [14 -17]questionedthe experimentalwork [6], becausetheynoticed thatt he measured liquidus [6]of the NiZr 2 phaseisextremelyasymmetricand abnormallysteep on the Niside,whichi st hermodynamicallyimprobable [19].Considering the discrepancybetween the calculations and the measurements,the eutectictemperaturebetween the NiZrand NiZr 2 compoundswasdetermined experimentallyin the presentwork.…”

“…[17]and Abeetal. [18]assessed the Ni-Zrsystem thermodynamicallyu sing the CALPHAD method,a nd obtained fivesets of optimized thermodynamicparameters fort his system.The biggest differencebetween the assessed [14 -18]phasediagramsand the experimentalones [6]isthe eutectictemperaturebetween the NiZrand NiZr 2 compounds. The experimentallymeasured temperaturewas1010 8 Cby Kirkpatrickand Larsen [6], while the calculated wasabout 1060 8 CbySaunders [14], 1065 8 CbyGhosh [15], 1111 8 C byYuand Jin [16]and 1078 8 CbyZaitsevetal.…”