High Pressure Melting Curve of Fe Determined by Inter‐Metallic Fast Diffusion Technique

Abstract

The planetary core heat flux is regulated by the insulating overlying mantle across the core-mantle boundary (CMB). The high-pressure melting curve of Fe is essential in assessing planetary core temperature because the inner core boundary (ICB) is a melting (or freezing) point of largely Fe alloys. Although, the temperature at the ICB should be adjusted to account for the effects of the light alloying elements (e.g.,

Equation of State of Liquid Fe7C3 and Thermodynamic Modeling of the Liquidus Phase Relations in the Fe‐C System

“…Those for solid fcc and hcp phases are adopted from Komabayashi (2014), which are consistent with recent experimental studies (Fei et al, 2016;Miozzi et al, 2020). The melting curve of Fe is required to calculate ∆G sol liq 1bar,T (Equation 4), but literature data published in the last decade show large variations, especially above 50 GPa (Anzellini et al, 2013;Aquilanti et al, 2015;Ezenwa & Fei., 2023;Hou et al, 2021;Jackson et al, 2013;Sinmyo et al, 2019;Zhang et al, 2016). Here we obtained a and b parameters in ∆G fcc liq 1bar,T and ∆G hcp liq 1bar,T for the melting curve of Fe to be in the middle of those reported by Anzellini et al (2013) and Sinmyo et al (2019), which represent relatively high and low estimations, respectively (Table 4, Figure 4a).…”

“…Those for solid fcc and hcp phases are adopted from Komabayashi (2014), which are consistent with recent experimental studies (Fei et al., 2016; Miozzi et al., 2020). The melting curve of Fe is required to calculate $${\increment}{G}_{1\text{bar},T}^{\text{sol}-\text{liq}}$$ (Equation 4), but literature data published in the last decade show large variations, especially above 50 GPa (Anzellini et al., 2013; Aquilanti et al., 2015; Ezenwa & Fei., 2023; Hou et al., 2021; Jackson et al., 2013; Sinmyo et al., 2019; Zhang et al., 2016). Here we obtained a and b parameters in $${\increment}{G}_{1\text{bar},T}^{\text{fcc}-\text{liq}}$$ and $${\increment}{G}_{1\text{bar},T}^{\text{hcp}-\text{liq}}$$ for the melting curve of Fe to be in the middle of those reported by Anzellini et al.…”

“… (a) The melting curve of fcc‐Fe (dashed lines) and hcp‐Fe (solid lines) calculated in this study (red) and a previous thermodynamic study (black) (Komabayashi, 2014). Experimental results are plotted as squares (Anzellini et al., 2013), triangles (Jackson et al., 2013), pentagons (Aquilanti et al., 2015), diamonds (Zhang et al., 2016), circles (Sinmyo et al., 2019), inverted triangles (Hou et al., 2021), and crosses (,Ezenwa & Fei, 2023). (b) $${\increment}{G}_{1\text{bar},T}^{\text{sol}-\text{liq}}$$ of fcc‐Fe (dashed lines) and hcp‐Fe (solid lines) in this study (red) and a previous thermodynamic study (black) (Komabayashi, 2014).…”