THERMOELASTIC NATURE AND CRYSTAL STRUCTURE OF THE Cu-Zn MARTENSITE RELATED TO THE SHAPE MEMORY.

Abstract

Low temperature ( minus 70 C) investigations on martensitic Cu-40Zn alloys were carried out by optical and electron microscopy and electron and x-ray diffraction. The crystal structure of the minus 70 C martensite was identified as a monoclinic lattice slightly different from the normal orthorhombic 9R type observed at room temperature. Internal defects were not twin faults but stacking faults on the (001) basal plane. The thermoelastic nature of the martensite transformation was established. The findings are compared with literature data for other alloys with a shape memory effect.