REAL-SPACE CHARACTERIZATION OF SHORT-RANGE ORDER IN CU-PD ALLOYS

Cu-Pd alloys containing 10, 20, 30, 40, and 50 at. % Pd and quenched f rom a temperature just above the ordering temperature T-c are investig ated by electron diffraction and high-resolution electron microscopy ( HREM). The results show diffuse electron diffraction intensities at {1 00} and {110} positions for the alloy with 10 at. % Pd, but with a cha racteristic twofold and fourfold splitting for the alloys with more th an 10 at. % Pd. High-resolution images show the formation of microdoma ins best developed between 20 and 30 at. % Pd. A real-space characteri zation has been performed by applying videographic real-structure simu lations revealing that the splitting of the diffuse maxima depends on the average distance between microdomains of Cu3Au type in antiphase w ith each other. By applying image processing routines on the HREM imag es, correlation vectors are identified which correspond to correlation s between microdomains.