Experimental study and computer modelling of the β⇒α + β phase transformation in β21s alloy at isothermal conditions

S. Malinov*, W. Sha, P. Markovsky

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    70 Citations (Scopus)


    The thermodynamics and kinetics of the β⇒α + β phase transformation in β21s alloy were studied at isothermal conditions in the temperature range 400-750 °C. Resistivity technique was used to trace 'in situ' the entire transformation for temperatures 650, 700 and 750 °C and the first parts of the transformation for temperatures 500 and 600 °C. X-ray diffraction was applied for quantitative analysis. The thermodynamic calculations suggested that the transformation is controlled by diffusional enrichment of the β phase with molybdenum. Disagreement between calculated and experimental phase equilibria for the alloy studied was observed. The kinetics of the β⇒α + β transformation were modelled under isothermal conditions in the theoretical frame of the Johnson-Mehl-Avrami (JMA) theory. Different mechanisms of the transformation are suggested. The JMA kinetic parameters were derived for the different mechanisms of the transformation. A good agreement between the calculated and the experimentally measured transformed fractions was found out. Time-temperature-transformation (TTT) diagram was designed for the β⇒α + β transformation in β21s alloy. Iso-lines were calculated and plotted tracing the amounts of the α phase. Good agreement between experimental and calculated TTT diagram is observed.

    Original languageEnglish
    Pages (from-to)110-118
    Number of pages9
    JournalJournal of Alloys and Compounds
    Issue number1-2
    Publication statusPublished - 13 Jan 2003


    • Crystal structure
    • High temperature alloys
    • Kinetics
    • Phase transition
    • X-ray diffraction

    ASJC Scopus subject areas

    • Mechanics of Materials
    • Mechanical Engineering
    • Metals and Alloys
    • Materials Chemistry

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