Microstructure processes induced by phase transitions in a CuAu alloy as studied by acoustic emission and optical cinematography

Combined acoustic emission measurements and surface cinematography observations have been applied to determine the structure evolution during thermal loading of the CuAu alloy. Thermal history and the fashion of thermal loading have been shown to affect considerably the structure response of the CuAu alloy on temperature changes. On thermal loading, intense plastic deformation occurs in certain temperature intervals due to the relaxation of internal stresses induced by phase transitions and structure anisotropy. The main mechanism is twinning laking place most probably in (110) planes. Dislocation glide and grain-boundary sliding have also been observed as minor mechanisms. A shape-restoration effect associated with the order-disorder transition is revealed. Thermal cycling with upper temperatures over 500 degrees C may also result in structural damage. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.