THE MUTUAL EFFECT OF IRON AND MANGANESE ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF ALUMINIUM –SILICON ALLOY

The effect of iron and manganese concentration on the morphology of complex intermetallics and their influence on the mechanical properties and microstructure has been studied in an Al-16.67 wt. % Si alloy with three content of iron (0.4, 1.2, 1.8 wt.%), and two different content of manganese, i.e. 0.6 and 0.9 wt.%. The intermetallic compounds are formed at high iron contents or at high concentrations of manganese with low iron. The microstructural investigation by Clemex software showed that the biggest intermetallic size reached the surface area of 12750 µm2, when the amount of iron was increased from 1.2 % to 1.8 % wt.%. It was also showed that the volume fraction of intermetallic compounds increases as the iron and manganese content increases. Formation of complex intermetallic phases with iron adversely affects tensile strength decreasing from 229MPa with 0.4 wt. % of iron to 187MPa when iron content was increased to 1.8 wt.%