Research On Micro-structure And Properties Of Boron High Entropy Alloys

High entropy alloy（HEA） is new alloy material with a variety of major elements, and each principal component atomic ratio is not more than 35%. B can play an significant solid solution strengthening effect in HEA and has been studied.While the Brittleness precipitated phase do harm to the Plastic property of alloy.A variety of high entropy alloys were producted with the smelting technology system in this article. We explore the high alloys micro-structure and Boride morphology From the perspective of high entropy effect、Aluminum element and rare earth elements Y with the X-ray diffraction, scanning electric, micro-hardness meter and nano indentation equipment.The results show that :the boron in alloy mainly exists in the form of solid solution and boride and the alloy morphology present a typical dentrite morphology,boride show the shape of long strip in the interdendritic precipitation, alloy entropy value increases with the increase of alloy principal component number and the micro-structure tend to be simple, amount of sigma and boride precipitates in the alloy reduce, gradually tend to be dispersed in the alloy, of precipitation strengthening and dispersion strengthening; The element Cr mainly exist in M2 B boride precipitates, Ni、Cu、Al mainly exist in the branch intracrystal line.FeCoNiCrAlxCu_0.7B_0.3 alloy is mainly composed of BCC and FCC solid solution. The FCC phase intensity of diffraction peaks decreases with the increase of the content of the element Al while the BCC phase reduce. The content of precipitates increase first and then decrease with the increase of entropy value.B can delay the FCC phase transforming into BCC phase; Alloy hardness gradually increased with the increase of Al content while the plasticity, fracture toughness reduce. The nano indentation coincides with the macroscopic mechanical properties of the basic. The precipitated phase dissolved spheroidizing trend to different extent after high temperature annealing and the BCC structure alloy hardness increased.High temperature annealing can improve the fracture toughness of alloy.Alloys were mainly consists of deposition dendrites after adding rare-earth yttrium alloy, and composition segregation exist obviously. The rare-earth yttrium main partial between dentrite and can elaborate dendrites to a certain degree and increase the strength and plasticity of high entropy alloy.