Experimental melting curve of zirconium metal to 37 GPa

Abstract

In this report, we present results of high-pressure experiments probing the melt line of zirconium (Zr) up to 37 GPa. This investigation has determined that temperature versus laser power curves provide an accurate method to determine melt temperatures. When this information is combined with the onset of diffuse scattering, which is associated with the melt process, we demonstrate the ability to accurately determine the melt boundary. This presents a reliable method for rapid determination of melt boundary and agrees well with other established techniques for such measurements, as reported in previous works on Zr.

A Review of the Melting Curves of Transition Metals at High Pressures Using Static Compression Techniques

“…Despite the numerous technological advancements that have been made in both fields during the last two decades, reliable measurements remain very challenging, especially at the high end of P-T conditions. The diverse results for different experimental approaches concerning Ta [13,[20][21][22][23], Fe [14,[24][25][26], Mo [13,15,[27][28][29][30][31][32][33], V [34,35], Ti [13,36], Zr [37,38], or Ni [39][40][41] clearly exhibit the need for a universally established methodology.…”

Ab initio inspection of thermophysical experiments for zirconium near melting

“…Our QMD calculations predict a substantial volume change on melting of about 2.6%, in addition to quite a low value of calculated enthalpy of fusion (≈ 14 kJ/mol). This fact leads to the steep slope of the melting curve at P = 0 of dT m /dP = 60 K/GPa predicted by QMD contrary to laser-heated diamond anvil cell experiments [5,121,122] where 24-28 K/GPa was proposed.…”

Nested Sampling of Materials’ Potential Energy Surfaces: Case Study of Zirconium

“…Repeating the NS calculations and post processing analysis at a series of different pressures provides the entire pressure-temperature phase diagrams for each potential model of interest, which can be seen in Figure 4 alongside experimental data [28,29]. From these results it is evident that only the Zr07 potential is capable of capturing the bcc-hcp transition, presenting an obvious predictive advantage over Zr95.…”

“…However, neither of the two potentials exhibit thermodynamic stability of the ω phase, which has been shown to be stable at low temperatures and above ∼5 GPa experimentally, highlighting an area for future improvements of these models. [28] and experimentally measured melting points [29], respectively. Blue symbols represent results of NS calculations with the Zr95 model [31] and red symbols correspond to NS results with the Zr07 model [32].…”

“…Zirconium has been the subject of several experimental and theoretical studies, due to its resistance to corrosion and favourable response to radiation damage. At lower pressures zirconium crystallizes in the body-centered cubic (bcc) structure, which transforms to the hexagonal close-packed (hcp) structure below 1136 K. With increasing pressure at room temperature, the hcp phase transforms into another hexagonal structure, often referred to as the ω phase, which is not close-packed and has three atoms per unit cell [28][29][30]. The first interatomic potential model we consider, henceforth referred to as Zr95, was developed by Ackland et al in 1995 [31], and uses empirical values of several crystalline properties (e.g., elastic constants, binding energy, the vacancy formation energy) to accurately reproduce properties of hcp zirconium.…”