Effects of Zr and Si Addition on Mechanical Properties of Al_0.5CoCrFeNi High-Entropy Alloys

Thermally sprayed heating coatings are a recent approach for temperature control in moulding tools. While there are material options in the lower temperature range up to T = 300 °C, new alloys have to be developed to improve the range of application. The Al_0.5CoCrFeNi high-entropy alloy (HEA) with further addition of Zr and Si shows favourable electrical properties due to severe lattice distortion. The alloy development was carried out with Al_0.5CoCrFeNiZr_xSi_y by arc melting. Thereby, the molar Zr content x was varied from 0 to 0.5 and the Si content y from 0 to 0.2. In order to evaluate the alloy’s prospective performance, the phase composition was studied by SEM with EDX and the fracture toughness was determined to estimate fracture properties, which are found to be a typical failure mechanism of heating coatings. The different HEA exhibit a typical dendritic microstructure with fcc dendrites and a bcc interdentritic phase. The hardness of the alloys increases with increasing bcc content, while the ductility decreases. With knowledge about the effects of Zr and Si on the electrical and mechanical properties, which are justified by the microstructure, Al_0.5CoCrFeNiZr_xSi_y HEA can be tailored specifically towards the needs of individual heating applications.