Phase equilibria in the system "MnO"-CaO-MgO-SiO2-Al2O3 with Al2O3/SiO2 weight ratio of 0.17 and MgO/CaO weight ratio of 0.25 at Mn-Si alloy saturation

Liquidus isotherms and phase equilibria have been determined experimentally for a pseudo-ternary section of the form "MnO"-(CaO+MgO)-(SiO2+Al(2)O3) with a fixed Al2O3/SiO2 weight ratio of 0.17 and MgO/CaO weight ratio of 0.25 for temperatures in the range 1 393-1 673 K. The primary phase fields found in the investigated section include manganosite (Mn, Mg, Ca)O; dicalcium silicate alpha-2(Ca, Mg, Mn)O center dot SiO2, merwinite 3CaO center dot(Mg, Mn)O center dot 2SiO(2); melilite [2CaO center dot(MgO, MnC, Al2O3). wollastonite [(Ca, Mg, Mn)O center dot SiO2]; diopside [(CaO, MgO, MnO, Al2O3)center dot SiO2]; tridymite (SiO2); 2(SiO2, Al2O3)], rhodonite [(Mn, Mg, Ca)O center dot SiO2]; anorthite (CaO center dot Al2O3-2SiO(2)) and tephroite [2(Mn, Mg, Ca)O center dot SiO2]. The liquidus temperatures and primary phase fields are significantly different to those in the ternary system "MnO"-CaO-SiO2, but are close to those previously reported pseudo-ternary section "MnO"(CaO+MgO)-(SiO2+Al2O3) for Al2O3/SiO2 weight ratio of 0.17 and MgC/CaO weight ratio of 0.17. The partitioning of CaO, MgO and MnO between liquid and solid phases was measured using EPMA, and the extents of solid solutions for a range of bulk compositions and temperatures were characterised.