Abstract:A TTT diagram for the precipitation formed at some intermediate temperatures through cooling from high temperature parent phase in a Cu-27.27Zn-3.73A1  alloy is established  by means of dilatometric measurement. The morphology and structure of transformation products formed at some intermediate temperatures isothermally through cooling from high temperature parent phase and up-quenching from DO₃ parent phase are studied by metallographic, X-ray and electron microscopy analyses. Three regions in the two separate C curves are obtained according to different morphology of precipitate: rod-like α, plate-like bainite and α rods, and bainite plates. Prolonged aging makes bainite plate change gradually into αwhose lattice parameters are no different from that of αformed equilibriumly from parent phase. The structure is almost orthorhombic long period structure for bainites formed from B₂ and DO₃ parent phase, but monoclinic for martensite from DO₃. They correspond to the overlapping and separating of (1 2 10) and (2 0 10) diffraction peaks respectively, showing the lower degree of ordering in bainite

Key words: Cu-Zn-A1 alloy   transformation at intermediate temperature   morphology and structure