MICROSTRUCTURAL CHARACTERIZATION OF A NEW ZN-BASED CREEP-RESISTANT ALLOY

A detailed microstructural characterization of a Zn-based creep-resist ant alloy (ZATEC(R)) has been carried out to determine the structure, composition and distribution of phases making up the microstructure. T his alloy is based on the ZA-8 chemistry but has an increased Mg conte nt, and very low Li and Mn contents. Analytical transmission electron microscopy, scanning electron microscopy and scanning Auger microscopy showed that the alloying elements Li, Mg, Mn and Cu are mainly found in the eutectic region of the alloy as compound particles or in the su persaturated eta phase, depending upon their local concentration. Mg h as been found to be present as Mg2Zn11 crystals or as concentrated Mg- containing areas. The microdiffusion patterns of Mn-containing phases had a characteristic fivefold symmetry, showing their existence as qua si-crystals. The microdiffraction patterns of Li-containing areas pres ent in eutectic regions could be indexed as LiZn4 or Al2CuLi.