The Fabrication and Heat-treating of Cu-based Alloy for Shape Memory Plates

This work is concerned with the development of a Cu-22.3mass%Zn-5.1mass%Al alloy that is potentially usable for shape memory devices. The influence of betatizing heat treatment parameters on the grain size of the alloy was evaluated. The optimal thermomechanical treatment for obtaining thin plates with final thickness below 1 mm was selected from the standpoint of least danger of crack occurrence, favorable microstructures and acceptable grain size. A good reliable shape memory effect in the alloy is observed for stepquenched specimens. The decrease in the phase transformation temperatures was observed during aging treatment from 200 to 400°C for times up to 30 hours. The apparent activation energy for the decrease in the transformation temperatures was determined as 63.9 ± 3 kJmol" .The conditions for producing a high quality memory device were suggested. K e y W o r d s : Cu-Zn-Al shape memory alloy, thermoelastic martensitic transformation, shape memory recovery