Based on (i) the low liquidus temperature of Si–Cu systems, (ii) low solubility of Cu in solid Si, and (iii) a strong affinity of Zr to B for the enhanced boride formation, a novel method to remove B from Si using Zr as a trapping agent via a Si–Cu solvent was developed in this study. B-bearing polygonal ZrB x precipitations found at the bottom of test samples were confirmed as ZrB2 by electron probe microanalysis. Thermodynamic analysis revealed that the solubility products of ZrB2 in a Si–Cu melt were 2.50 × 10–12 (1258 K, Si-57.0 atom % Cu) and 4.11 × 10–12 (1345 K, Si-50.0 atom % Cu). Finally, the compositions of Si–Cu alloys that can form stable ZrB2 particles were estimated by calculating the solubility products of ZrB2 and the equilibrium contents between B and Zr at different corresponding liquidus temperatures. The proposed method provides the potential for B removal via Si–Cu solvent refinement to realize the large-scale production of solar-grade silicon, thereby overcoming the key limitation to the sustainable utilization of solar energy.

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The effect of manganese on the thermodynamic property of tellurium in molten iron was experimentally evaluated as an interaction parameter using a vapor-liquid equilibration technique, where the vapor pressure of tellurium was controlled using the transpiration method. Manganese was found to stabilize tellurium in molten iron and its effect was relatively small compared to other alloying elements.

CoCrCuFeNi high-entropy alloys (HEAs) have high ductility owing to their unique two-phase microstructure. Phase relations and microstructure evolution were investigated by scanning electron microscopy coupled with energy dispersive spectrometry and differential thermal analysis. These results contributed to clarifying the formation mechanism of the HEA microstructures. The effects of Mg addition as an alloying element in HEAs were also studied, with respect to precipitation hardening, thereby aiming to obtain strength-ductility balanced HEAs.

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