In situ X-ray study of order–disorder phase transitions in Cu–Al–Be melt spun ribbons

The disorder–order phase transitions in Cu– Al–Be shape memory alloys were studied by in-situ X-ray diffraction. Isothermal measurements in an inert gas chamber were made on ribbons of Cu–Al–Be alloys, obtained by melt spinning. A position sensitive detector was used for a fast record of the X-ray signal on a h–h geometry diffractometer. Each ribbon was used as the heating element, avoiding the need of a heating sample holder and obtaining a better measurement of the temperature with a thermocouple attached directly to the ribbon. The order transition was followed at different temperatures after a high temperature annealing (700 C) in the disordered b-phase region. A first order transition was observed from disordered b (A2) to ordered b1 (DO3), without prior b (B2) ordering. No precipitation was detected during this fast measuring procedure