FeSe-MnSe phase relationships in the presence of excess iron
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Fig. 2--The FeSe-MnSe system (with excess metallic iron) drawn from the results of this study.
Fig. 1--The FeSe-MnSe system (with no excess metallic iron) drawn from the results of this study only. bility curves, especially for the FeSe-rich phase, showed a discontinuity between 700 and 800°C (973 t o 1073 K). B a s e d on the DTA data and the above observations, a eutectoid invariant is proposed at ~740°C (1013 K).
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FeSe-MnSe System (With E x c e s s Metal)
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In o r d e r to simulate steel equilibria more closely, the FeSe-MnSe relationships were investigated in the presence of metallic iron, thus establishing a portion of the ternary system, Fe-Mn-Se. Data which are presented in Table III and the phase d i a g r a m of Fig. 2 are based on the following observations. 1) T h e r e is a eutectic of iron, ~', and liquid in the F e - S e system at 952°C (1225 K). 2) The DTA experiments revealed an invariant at 976°C (1249 K) which proved t o be a peritectic. 3) A metallographic examination showed the presence of liquid down t o ~920°C (1193 K). An extrapolation of the liquidus curve suggests approximately 9 wt pct MnSe in the liquid minimum. 4) Microprobe analyses showed solubility limits of 25 wt pct MnSe in FeSe, and 48 wt pct FeSe in MnSe at the peritectic temperature (976°C, or 1249 K). The compositional shifts in the solid solution r a n g e s were monotonic as shown by microprobe analyses. Furthermore, each solid selenide phase was essentially stoichiometric in the presence of e x c e s s iron. Under these conditions, t h e r e was only a slightly detectable change observed in the solubility of MnSe in the FeSe-rich phase at the ~ - t o - ~ ' transition. Fe-FeSe-MnSe-Mn Liquidus Fig. 3 proposes a pattern for the univariant lines between the various solubility surfaces of the F e - F e S e MnSe-Mn portion of the ternary d i a g r a m . The bounding binaries utilize the F e - M n system from the Metals METALLURGICAL TRANSACTIONS B"
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Fig. 3--Liquidus phase relationships (Fe-FeSe-MnSe-Mn). Binary Invariants: e1-952°C (1225K); e2-977°C (1250 K); e3-~1230°C (1500 K); ml and m2->1000°C (1273 K); m3 and m4-~1500°C (1770 K). Ternary Invariants: E1-920°C (1193K); Pt--976°C (1249 K); M1 and M2--1500°C (1770 K). Compositions: e r 4 8 wt pet Se; e2-~35 wt pct MnSe; EI~9 wt pet MnSe, and 90 wt pct FeSe; P l - ~ 9 wt pct MnSe. 90 wt pct FeSe, and 1 wt pet Fe. Ha
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