In this work, the design, microstructures and mechanical properties of five novel non-equiatomic lightweight medium entropy alloys were studied. The manufactured alloys were based on the Al₆₅Cu₅Mg₅Si₁₅Zn₅X₅ and Al₇₀Cu₅Mg₅Si₁₀Zn₅X₅ systems. The formation and presence of phases and microstructures were studied by introducing Fe, Ni, Cr, Mn and Zr. The feasibility of CALPHAD method for the design of new alloys was studied, demonstrating to be a good approach in the design of medium entropy alloys, due to accurate prediction of the phases, which were validated via X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. In addition, the alloys were manufactured using an industrial-scale die-casting process to make the alloys viable as engineering materials. In terms of mechanical properties, the alloys exhibited moderate plastic deformation and very high compressive strength up to 644 MPa. Finally, the reported microhardness value was in the range of 200 HV_0.1 to 264 HV_0.1, which was two to three times higher than those of commercial Al alloys.

The aim of this work is to study the microstructure of four high entropy alloys (HEAs) produced by large scale vacuum die casting. Al₄₀Cu₁₅Mn₅Ni₅Si₂₀Zn₁₅, Al₄₅Cu₁₅Mn₅Fe₅Si₅Ti₅Zn₂₀, Al₃₅Cu₅Fe₅Mn₅Si₃₀V₁₀Zr₁₀, and Al₅₀Ca₅Cu₅Ni₁₀Si₂₀Ti₁₀ alloys formed a mixture of different structures, containing intermetallic compound (IC) and solid solution (SS) phases. The phases observed in the casting alloys were compared with the equilibrium phases predicted by Thermo-Calc. The measured densities varied from 3.33 g/cm⁻³ to 5.07 g/cm⁻³ and microhardness from 437 Hv to 887 Hv. Thus, the microhardness and estimated strength/density ratios are significantly higher than other lightweight high entropy alloys (LWHEAs).

El análisis térmico ha sido usado como una herramienta de control de calidad desde hace tiempo en las plantas de fundición de aluminio. Recientemente ha sido reconocido que el análisis de la curva de enfriamiento y su primera derivada ofrecen algunos otros parámetros que pueden ser usados de manera exitosa en los programas de simulación para mejorar su precisión. Los nuevos desarrollos en el análisis de la curva de enfriamiento aplicando las derivadas de orden superior han mostrado que la técnica del análisis térmico puede aplicarse para calcular la cantidad de precipitados en el proceso de solidificación. Este artículo proporciona una pequeña revisión de la aplicación de la curva de enfriamiento en las plantas de fundición de aluminio y del efecto del plomo sobre las temperaturas características de solidificación de la aleación AlSi6Cu4.

In this work, three novel complex concentrated aluminum alloys were developed. To investigate the unexplored region of the multicomponent phase diagrams, thermo-physical parameters and the CALPHAD method were used to understand the phase formation of the Al₈₀Mg₅Sn₅Zn₅Ni₅, Al₈₀Mg₅Sn₅Zn₅Mn₅, and Al₈₀Mg₅Sn₅Zn₅Ti₅ alloys. The ingots of the alloys were manufactured by a gravity permanent mold casting process, avoiding the use of expensive, dangerous, or scarce alloying elements. The microstructural evolution as a function of the variable element (Ni, Mn, or Ti) was studied by means of different microstructural characterization techniques. The hardness and compressive strength of the as-cast alloys at room temperature were studied and correlated with the previously characterized microstructures. All the alloys showed multiphase microstructures with major α-Al dendritic matrix reinforced with secondary phases. In terms of mechanical properties, the developed alloys exhibited a high compression yield strength up to 420 MPa, high compression fracture strength up to 563 MPa, and elongation greater than 12%.