Accession Number : AD0284002

Title :   ORDERING OF CUAU I

Corporate Author : RUTGERS - THE STATE UNIV NEW BRUNSWICK N J BUREAU OF ENGINEERING RESEARCH

Personal Author(s) : WEISSMANN,SIGMUND

Report Date : AUG 1962

Pagination or Media Count : 1

Abstract : A study was made of the ordering of CuAu. The phenomena were investigated by transmission electron microscopy of thin foils prepared from the bulk. These studies were complemented by a quantitative strain analysis based on data provided by the x-ray back-reflection divergent beam method. At low ordering anneals (100 C for 2 hr), ordered plate-like CuAu I nuclei are formed. The lattice strains resulting from the transformation of the disordered face-centered cubic structure to the ordered tetragonal CuAu I build up with increasing annealing temperature or annealing time until short-range strain accommodations take place in the form of microtwinning. Microtwinning occurred on (101) planes and is characterized by a regular alternation of the unique c-axis direction. At ordering anneals at higher temperatures, coarse (101) twin lamellae are formed. The quantitative strain analysis carried out with the aid of a computer showed that the onset of twinning was associated with a marked decline in the strain distribution. This decline corresponded to the ordering stage at which the coherency strains between ordered nuclei and disordered matrix were elminated. (Author)

Descriptors :   *COPPER ALLOYS, *GOLD ALLOYS, *INTERMETALLIC COMPOUNDS, *MOLECULAR ASSOCIATION, CRYSTAL LATTICES, CRYSTAL STRUCTURE, CRYSTALLIZATION, CRYSTALS, ELECTRON MICROSCOPY, HEAT TREATMENT, METAL FILMS, PHASE STUDIES, STRESSES, X RAY DIFFRACTION

Distribution Statement : APPROVED FOR PUBLIC RELEASE