Density and related thermophysical properties of metastable liquid Ni-Cu-Fe ternary alloys

The densities of liquid Ni-Cu-Fe ternary alloy system were investigated by molecular dynamics method in combination with a MEAM (Modified Embedded Atom Method) potential model. The temperature range is from 1000 to 2200 K, including both a broad superheating range and a large undercooled regime. The densities of six Ni_{100 - 2 x} Cu_x Fe_x alloys (x = 0, 10, 20, 30, 40, 50) decrease linearly with the rise of temperature at the superheated and undercooled states, and increase with the enhancement of Ni content. Among the simulated alloys, the densities of only liquid pure Ni and Ni₆₀Cu₂₀Fe₂₀ alloy are available in literatures, which are in good agreement with the calculated values. According to the relationship between the excessive volume and the alloy composition, it can be deduced that Ni_{100 - 2 x} Cu_x Fe_x alloys deviate from ideal solution. Moreover, a comparison was also performed between the calculated results and the approximated values by Neumann-Kopp's rule. Based on the obtained density data, the thermal expansion coefficients are also derived. It firstly decreases to a minimum value, and then displays a rise with the increase of Ni content.