Research on Isothermal Phase Transformation Kinetics of TC21 Alloy

The kinetics of the martensite decomposition in TC21 alloy under isothermal conditions has been studied using dilatometry technique. The typical morphologies of decomposition products were also directly observed. At 500 degrees C and 550 degrees C, the mechanism of martensite decomposition occur by (alpha '' -> alpha + alpha '')(enriched) (-> alpha + beta)(metastable) (-> alpha + beta) at temperature between 600 degrees C and 750 degrees C, the martensite decompose by (alpha '' -> alpha' + beta)(metastable) (-> alpha + beta). up 800 degrees C, the martensite directly transform to alpha and beta phase. Time temperature transformation diagram with iso-lines tracing the amount of the martensite decomposition have been established.