Mats Hillert approach to growth kinetics of diffusional phase transformations in crystalline solids

The Hillert approach to analysis of growth kinetics assumes that interphase boundaries are disordered and thus normally offer negligible resistance to growth. An evaluation of the present status of this assumption is made upon two bases. The first utilizes growth kinetics data taken at low enough resolutions in space and time so that the role of ledges is not directly detectable. The second basis examines interfacial structure as well as growth kinetics, at resolutions sufficient to observe ledges and to evaluate their role during growth. Lengthening and thickening of plates and of grain boundary allotriomorphs, growth kinetics of massive transformations and edgewise growth of pearlite are considered upon both bases. On the first, the disordered boundary assumption usually works well. On the second basis the interphase boundary closely spaced, the disordered boundary assumption is often a useful approximation.