Fabrication of Nanocrystalline AlCoCrFeNi High Entropy Alloy through Shock Consolidation and Mechanical Alloying

Abstract

High entropy alloys (HEAs) are usually fabricated using arc melting which has the disadvantages of diseconomy, and the limitations in the shape and size of final products. However, recently, quite a large amount of research has been carried out to find the fabrication techniques for HEAs with better properties such as mechanical alloying and rapid solidification. In this paper, an AlCoCrFeNi high entropy alloy was successfully fabricated by the shock consolidation technique. In this method, the starting powders were mixed by mechanical alloying and then the shock wave was imposed to the compacted powders by explosion. High levels of residual stress existed in samples fabricated by the shock consolidation method. Due to this, after fabrication of the sample, heat treatment was used to eliminate the residual stress and improve the mechanical properties. The microstructure of the samples before and after heat treatment were examined by XRD, SEM and electron backscatter diffraction (EBSD). The shock consolidated sample and sample with heat treatment both showed the nano-structure. After heat treatment the hardness of the sample was decreased from 715 HV to the 624 HV, however the failure strength increased, and as expected the ductility of the sample was improved after heat treatment.

Formation of Novel Bimetal Oxide In2V2O7 through a Shock Compression Method

“…Through this technology, the shockwave acts on a target material to generate ultrahigh pressures (10 0 –10 2 GPa) and temperatures (10 2 –10 4 K) in microseconds, inducing multiple physical and chemical phenomena. Consequently, shock loading approaches have been widely applied in various material processing fields, such as metallic material hardening, − material doping, synthesis of novel materials, − shock-induced phase transformation, , and shock activation of materials . With respect to this method, several techniques have been developed to adjust the pressure and temperature during shock compression for the synthesis of materials, such as organic molecules using inorganic precursors, nanodiamonds, doped TiO 2 , and doped graphene .…”