Solid State Amorphization and Alloy Parameters for High Entropy Alloys

Fast electron irradiation can induce the solid-state amorphization (SSA) of many intermetallic compounds. The occurrence of SSA stimulated by fast electron irradiation was found in the Al0.5TiZrPdCuNi high-entropy alloy (HEA). The relationship between the occurrence of SSA in intermetallic compounds under fast electron irradiation and the empirical alloy parameters for predicting the solid-solution-formation tendency in HEAs was discussed. The occurrence of SSA in intermetallic compounds was hardly predicted, only by the alloy parameters of δ or ΔHmix, which have been widely used for predicting solid-solution formation in HEAs. All intermetallic compounds with ΔHmix ≤ -35 kJ/mol and those with δ ≥ 12.5 exhibit the occurrence of SSA. This implies that the intermetallic compounds with a largely negative ΔHmix value and a largely positive δ parameter are favorable for the occurrence of SSA.

Modeling and Experimental Results of Selected Lightweight Complex Concentrated Alloys, before and after Heat Treatment

Lightweight complex concentrated alloys (LWCCA), composed of elements with low density, have become a great area of interest due to the high demand in a large number of applications. Previous research on LWCCAs was focused on high entropy multicomponent alloy systems that provide low density and high capability of solid solution formation. Present research introduces two alloy systems (Al-Cu-Si-Zn-Mg and Al-Mn-Zn-Mg-Si) that contain readily available and inexpensive starting materials and have potential for solid solution formation structures. For the selection of appropriate compositions, authors applied semi-empirical criteria and optimization software. Specialized modeling software (MatCalc) was used to determine probable alloy structures by CALPHAD, non-equilibrium solidification and kinetic simulations. The selected alloys were prepared in an induction furnace. Specimens were heat treated to provide stable structures. Physicochemical, microstructural, and mechanical characterization was performed for the selected alloy compositions. Modeling and experimental results indicated solid solution-based structures in the as-cast and heat-treated samples. Several intermetallic phases were present at higher concentrations than in the conventional alloys. Alloys presented a brittle structure with compression strength of 486–618 MPa and hardness of 268–283 HV. The potential for uniform intermetallic phase distribution in the selected alloys makes them good candidates for applications were low weight and high resistance is required.