Comments on ‘Response to “The Phenomenological Theory of Martensite Crystallography (PTMC) versus the Topological Model (TM)”’

Abstract

In a paper presented at ICOMAT 2008 [1], it was pointed out that the Topological Model (TM) analysis, in the form that had appeared in the literature to date, contained three errors. The consequences of these errors was that the TM predictions of the interface habit plane - particularly in the case of the analysis based on the 'overlap step height' h and incorporating partitioning - did not agree with those of the Phenomenological Theory of Martensite Crystallography (PTMC). The major consequence of this discrepancy between the two sets of interface habit plane predictions was that the TM version was not consistent with the condition of 'no long range strain' in the habit plane. It was demonstrated that the errors in the TM analysis could be very easily corrected by substituting the 'mean step height' for the 'overlap step height' h in the major equation used to determine the inclination of the interface habit plane to the terrace planes in the two phases. This led to very good agreement between the PTMC and the TM and ensured that there was now no long range strain in the interface habit plane. This ICOMAT 2008 paper has generated a response from the major proponents of the TM [2]. This response concludes that the criticisms in the original paper [1] are 'misguided', that the TM analysis does in fact lead to the correct 'rigorous determination of equilibrium habit planes' and that this state has 'not been correctly determined by Kelly [1]'. The purpose of this paper is to comment on the response by Hirth and Pond [2] and to show that many of their conclusions are based on misconceptions about the PTMC or misunderstandings of the corrections to the TM presented in the original paper [1].