EFFECT OF SEVERE AUSFORMING ON THE SHAPE MEMORY MICROSTRUCTURE OF A COPPER BASED ALLOY

Thermomechanical treatments provide requirements of good mechanical properties withal better and precise shape memory properties. The present work has been studied morphology, chemical structure and elemental mapping of Cu-based shape memory alloys after ausforming applied at high temperature range. Ausforming implies plastic deformation of austenite, introduced lattice defects which modify structure of martensite and increase strength of the alloys. Thus, ausformed alloys have great potential for novel actuators in commercially valuable applications, at certain transformation temperatures. The samples plastic deformed with different deformation degree were systematically investigated by scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX). Subtle changes in composition have been studied for ausformed samples in different conditions (temperature of deformation between 1000 degrees C and 800 degrees C, deformation degree from 8 to 40%) to determine the properties of CuAlNi shape alloys and become workable in the production. Transformation temperatures of specimens determined by DSC were correlated with changing the structure of martensite.