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.%.
In the present study, microstructure, hardness, and abrasion resistance of a heat-treated high carbon-high chromium steel (FMU-11) used in the cement mills were investigated. To investigate the best heat-treating cycle for the FMU-11 steel, three sets of samples were heat treated. The first set was tempered two times, the second set was re-hardened, and the third set was cryogenically heat treated. These samples were then compared with the conventionally heat-treated samples. The samples' microstructure was studied using an optical microscope, where traditional black and white etching, as well as color etching, were used. Scanning electron microscopy (SEM) was applied for higher magnification studies and in-depth analysis of the chemical composition. The mechanical properties were investigated by measuring the hardness and the wear resistance for the samples heat-treated in different cycles. The results showed that the cryogenic treatment and double-tempered samples had the highest hardness and wear resistance. In addition, the results showed that the re-hardening operation caused the carbides to be finely separated and evenly distributed in the steel matrix. The wear test results illustrated that the wear mechanism could be the delamination wear and the abrasive wear combined.