Iron-Molybdenum Phase Diagram in the Temperature Range of 1360 to 1622°C

Abstract

Steelmaking temperature region of the phase diagram for Fe-Mo binary alloy was reexamined by the heat treatment and microstructure studies of the Fe-Mo alloy samples. Fe-Mo alloy samples of 30 to 88 at%Mo were annealed at temperatures 1 529 to 1 622°C and quenched into water. The heat treated samples were examined with optical microscope, EPMA and X-ray diffractometer.
The invariant reaction between liquid, σ and Mo solid solution phases is found to be expressed as
σ (56 at %Mo) = Liq. (38 at %Mo)+(Mo) (75 at %Mo), at 1610°C,
where values in the parentheses are the composition of the respective phase. This result is in good agreement with the results obtained in the previous studies namely Knudsen cell mass spectrometric measurement of the activities in the Fe-Mo binary alloys and Knudsen cell mass spectrometric thermal analysis of the Fe-Mo binary alloys.
A revised Fe-Mo binary alloy phase diagram is proposed on the basis of the present results along with the above mentioned previous results.