The application and interpretation of the “time law” to the growth of β grain size and martensite plate thickness in copper-based martensites

Abstract

Isothermal growth of β grain size in Cu-Al and Cu-Al-Zn martensitic alloys can be described approximately by the well-known “time law”, D=K. t ⁿ. The martensite plate size (thickness) d _m , formed in quenched β grain is a function of the β grain size, {ie1290-01}. The mutual relationship can, to a good approximation, be described by the expression {ie1290-02}, where C 1, which means that the exponent n for β grain size is three times that for the martensite plate size. This important empirical relationship emphasizes the fact that while the β grains can grow in three dimensions, the martensite plate can grow only in one dimension, i.e. in a direction perpendicular to the austenite/martensite interface. A Hall-Petch relationship exists between the yield stress and the β grain size and the martensite plate thickness.