Two Kinds of Monoclinic-I Martensite and some Insight into the Microstructures they Form

By analysing the facet structure of the convex polytope generated by the twelve transformation strains of cubic to monoclinic-I martensite, we show that there are two different kinds of monoclinic-I martensite. These two kinds differ in the sign of a material parameter. While the symmetry properties of both kinds are the same, the geometrical structure of the set of recoverable strains is different. A key idea is to consider the convex polytope formed by the transformation strains and to study its facets. Another insight is to use invariant theory to exploit the fact that compatible cones are algebraic surfaces. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)