Effect of heat treatment processes applied on Al-Cr-Mn eutectic alloy on microstructure, mechanical and thermoelectical properties

In this study, eutectic Al-0.3% Cr(wt)-2.0% Mn(wt) alloy was formed by directional solidification in the casting furnace using high purity aluminum (99.9%), chromium (99.99%) and manganese (99.98%) elements. Afterwards, these eutectic alloy samples were subjected to heat treatment at 350oC for 1, 3, 6 and 18 hours. The heat treatment was carried out with Nüve Mf 110 muffle furnace. The microstructure changes, mechanical and thermoelectrical properties of the samples after heat treatment were examined, and the effect of heat treatment on these parameters was examined. Microstructure images were taken with a FEI-Quanta FEG 250 model scanning Electron Microscope (SEM). Qualitative and quantitative elemental analyzes of the phases in the microstructure were performed with Energy Dispersion Spectrometry (EDS). Additionally, X-Ray Diffraction (XRD) peaks were taken and image mapping was performed to support the determined stages. The hardness of both non-heat-treated and heat-treated samples was determined using the Future Tech FM700 model Vickers hardness tester. A 100-gram load was applied over a period of 10 seconds. Tensile strength tests were carried out on cylindrical samples with a diameter of 4 mm and a length of 60 mm in accordance with the ASTM E4 standard, with a Shimadzu Universal Tester at a strain rate of 1 mm/min at ambient temperature. Additionally, the effect of the heat treatment process on the thermophysical properties of the alloy was investigated by the Differential Thermal Analysis (DTA) method. In this context, changes in melting temperature, fusion enthalpy and heat capacity, which are important in characterizing the kinetics of the liquid-solid phase transition, were examined. Keywords: Eutectic alloy, Microstructure, Mechanical properties, Heat capacity