CHARACTERIZATION OF DEFORMED AND AS-CAST MICROSTRUCTURE OF COPPER-ALUMINUM-IRON ALLOYS .2. INFLUENCE OF INCREASED FE SOLUTE (ALPHA-PHASE)(BETA)

Five compositions of aluminium iron bronze in the (alpha+beta)-phase r egion containing 2.5 to 5 at.% Fe and 5 to 15 at.% Al have been prepar ed for microstructural characterization by X-ray diffraction line-prof ile analysis; optical and scanning electron microscopy, microhardness and magnetic susceptibility studies. The solute dependence of the defe ct parameters as revealed from X-ray study reflect the microstructural evolution in the deformed state especially near the alpha/(alpha + be ta) boundary. The influence of increased presence of Fe results in the lowering of stacking fault energy of pure Cu. Optical and scanning el ectron microscopy reveal the grain sizes and grain boundary structure, containing dispersed Fe-rich precipitates, Fe3Al. Microhardness studi es of the alloys depict the cumulative influence of Al and Fe3Al preci pitates in increasing the hardness (from 79.0 to 139.5 Kg/mm(2)). Thes e Fe-rich precipitates are primarily responsible for increased ferroma gnetic behaviour of the materials.