Preparation and microstructure and properties of AlCuFeMnTiV lightweight high entropy alloy

A new type of AlCuFeMnTiV lightweight high entropy alloy (LWHEA) was prepared by mechanical alloying (MA) and spark plasma sintering (SPS). The effects of milling time on the phase evolution of alloy powders and sintering temperature on the microstructure and mechanical properties of alloy blocks were investigated. The results show that the powders can be alloyed after 36 h high-energy ball milling, forming a BCC solid solution, and the alloying sequence is related to the melting point of the alloy elements. After being sintered by SPS, the alloy block is mainly composed of the BCC matrix, and the B2 phase (ordered BCC phase) and the HCP phases are precipitated from the matrix during the sintering process. Besides that, the Cu-rich FCC phase is distributed at grain boundaries. Nano twins are found in some FCC phases, which have a good strengthening effect on the grain boundary so that the alloy maintains high strength and good plasticity. The block sintered at 1050 °C exhibits the best comprehensive mechanical properties, with the density of 6.28 g⋅cm−3, hardness of 618.44 HV, compressive strength and yield strength of 2630 MPa and 2060 MPa respectively, the plastic strain of 15.83% and specific strength of 418.79 MPa⋅cm3⋅g−1, which is superior to most LWHEAs and traditional lightweight alloys.