Microstructural path analysis of martensite burst

Abstract

Modeling the martensite reaction requires reckoning with spatial aspects of the reaction. For that, we used formal kinetics, more specifically, the microstructural path method (MPM) to analyze the microstructure observed in a burst. The microstructural path analysis revealed that the size of the spread cluster in extended space, characterized by the Vandermeer and Juul-Jensen's impingement compensated mean intercept length, λ G , remained constant, independently of the parent austenite grain size. Moreover, current analysis introduced a purely formal description of the reaction progress by taking the parent austenite grain size as the progress variable. This description worked very well and resulted in a relationship between the volume fraction of partially transformed austenite, V VG , and austenite grain size, λ G . The significance of these findings in the light of the advantages and disadvantages of formal kinetics is discussed.

Evolution of Ms Temperature as a Function of Composition and Grain Size

“…The first one considers the effect of PAGS on the M s temperature related to the burst phenomenon [21] taking place during the austenite to martensite transformation. [22,23] The burst phenomenon is defined as the ability of martensite plates to activate the appearance and growth of other plates in an autocatalytic way and stimulated by elastic strain. [21] Rios and Guimaraes [23] showed that the burst phenomenon is more promoted in bigger austenite grains; consequently, the decrease of grain size decreases the amount of formed martensite at a certain temperature, thus delaying the detection of the M s temperature.…”

“…[22,23] The burst phenomenon is defined as the ability of martensite plates to activate the appearance and growth of other plates in an autocatalytic way and stimulated by elastic strain. [21] Rios and Guimaraes [23] showed that the burst phenomenon is more promoted in bigger austenite grains; consequently, the decrease of grain size decreases the amount of formed martensite at a certain temperature, thus delaying the detection of the M s temperature. Another theory proposes Hall-Petch strengthening of austenite with the decrease of PAGS, [24] leading to a greater resistance at the nucleation stage and, thus, requiring a higher undercooling to start the martensitic transformation.…”

Fractal Geometry and Porosity

“…Eq. (14), as written, is compatible with a volume, r 3 , for a pore of radius r and D p describes the pore space. The result for the total porosity derived from Eq.…”

“…The phenomenon of fractal is ubiquitous in a wide array of materials, such as the fracture of nanoparticle composites [6][7][8], the growth of crystal [9][10][11][12], the quasicrystal structure [13], the fracture of martensite morphology [14,15], the porous materials [16][17][18][19], and the deposited film [20][21][22][23][24][25]. These materials are of uncommon class of disordered materials and usually show complex microstructures.…”

Quantitative interpretation of martensite microstructure

“…The MPF is an important tool to analyze property-microstructure correlation as well as fundamental aspects of phase transformations 9 , such as the rate of autocatalytic martensite nucleation [10][11][12][13][14][15] . The microstructural path function (MPF) expresses the volume density of the product-matrix interfaces as a function of the fraction transformed,…”