Preparation And Effect Of Alloying Elements On Microstructure And Properties Of High Entropy Alloys

Since the concept of high entropy alloy was proposed, which caused more andmore people research it. Most of high-entropy alloys have high hardness, strength,anti-oxidation against heat treatment and corrosion resistance, but high-entropy alloyshave not been widely applied and they are still in the research stage. We mainlyprepare high entropy alloys and discuss the effect of alloying elements onmicrostructure and properties of high entropy alloys.We prepared AlFeCoNiCrSn_x, FeCoNiCuTiV_x and AlFeCoNiCuVSn_x highentropy alloy and AlFeCoNiCuZrV high entropy alloy target by using vacuummelting furnace successfully in pure argon atmosphere. Then we preparedAlFeCoNiCuZrV high entropy thin film by using FJL-560a magnetron sputtering andion beam sputtering equipment according to different gas flow. The main results areas follows:（1） When Sn content is low, the AlFeCoNiCrSn_x high entropy alloys showonly body centered cubic（BCC） structure and have good strength and plasticity. Thegrain boundaries emergence the Co3Sn2intermetallic compound with increasing Sncontent, and it can decrease the plasticity of alloy; The maximum strength and strainvalue of alloy is2180MPa and11.5%.（2） The AlFeCoNiCuVSn_x high entropy alloysdid not change the structure with adding Sn element, because it becomes solidsolution with other elements. and AlFeCoNiCuVSn_x high entropy alloys precipitatemany nanoparticles, these nanoparticles hinder the dislocation motion, so the strengthof alloys increases; The strength and plasticity of alloys can increase by addingappropriate Sn contents, and the maximum strength and strain value of alloy is1580MPa and13%.（3） When vanadium content is0, the FeCoNiCuTiV_x alloys didnot form a single solid solution and have some other complex phases, and thestructure of alloys are composed by body centered cubic（BCC） and face centeredcubic（FCC）; The strength of alloys increase with increasing the content of vanadium, because the radius of vanadium atom is larger then others, the crystal generated latticedistortion, so the strength of alloys increases，The maximum strength value ofFeCoNiCuTiV_x high entropy alloy is2480MPa.（4） We prepared the AlFeCoNiCuZrVhigh entropy alloys thin film according to different gas flow R（O₂/Ar） and the thinfilms are all amorphous, it can show that the amorphous ability of thin films is good.The AlFeCoNiCuZrV high entropy alloys thin film has fine hardness and Young’smodulus, The value of hardness and Young’s modulus are11.331GPa and182.614GPa, when the content of O₂is0. But the value of hardness and Young’smodulus are decrease, when the content of O₂is10%. This maybe amorphous clusterof thin film becoming larger and the dense becoming smaller；The value of hardnessand Young’s modulus become increase with increasing the content of O₂, this maybeformation of strong metallic oxide bond （Me-O）. The surface roughness of thin filmbecomes larger by increasing the content of O₂, but the thickness of thin filmsdecreases, because the number of metallic oxide becomes more and more withincreasing the content of O₂, and the energy was allocation by O ion in ionization, andthe metallic oxide deposited on substrate, Reaction and doping increase the internalstress and inhibit the growth of thin films，so the thickness of thin films becomesthinner.