Burst Phenomenon in the Martensitic Transformation

Microstructural Path Analysis of Martensite Dimensions in FeNiC and FeC Alloys

“…It is claimed that the apparent-activation energies above obtained characterize the thermal process that underlies the austenite plasticity and/or the transfer of dislocations into the martensite 40 . As already mentioned the importance of the austenite plasticity on the size of martensite has been brought up in the first half of the XX century 3,4 and, more recently, extended to isothermal martensite 41 . Finally, it is germane to note that the analysis of the intrinsic dimensions of martensite based on the JMAK equations yielded results compatible with previous investigations of the martensite substructure and growth in similar alloys above reviewed.…”

“…The growth is usually very fast. Growth stops when the unit reaches a certain size delimited by impingement and/or by the austenite plasticity 3,4 . Coarsening is not observed.…”

Athermal Martensite Transformation Curve

“…These alloys were used to investigate different aspects of the martensite transformation 3,5,[24][25][26][27][28][29] that have sub-zero transformation. Thence, these alloys are amenable to metallographic analysis at room temperature to characterize the progress of the transformation at different temperatures.…”

Martensite Transformation Intergrain and Intragrain Autocatalysis in Fe-Ni alloys

“…The development of multi-variant nuclei therein yields the transformation 5,6 . Martensite propagates rapidly 7,8 , however, its displacive character prevents martensite crossing high-angle boundaries. Its growth is frequently halted by impingement.…”

“…Its growth is frequently halted by impingement. Impingements between martensite plates generally yield autocatalytic nucleation events that speeds up the transformation 7 . These specificities are the sources of unique microstructure/property relationships that continue to be used to develop engineering materials.…”