The Study Of CrNiFeCoCuTi_xAl_1-x And CrNiFeCoCuTi_y High Entropy Alloy For The Microstructure And Properties

High entropy alloy is a new kind of alloy developed in the breakthrough of traditional alloy design concept. Alloying elements with the approximative molar ratio are melted, showing the multi-master effect, and breaking through the pattern of the traditional alloys with a primary matrix. Owning to the high-entropy effects, the crystal structure of alloys are impeled to be simple, and also nanocrystalline or amorphous materials would precipitate, so that the properties of the alloys are greatly improved, leading to the high strength, high hardness, corrosion resistance, high temperature oxidation characteristics and so on.In this paper, the microscopic structures and mechanical properties of CrNiFeCoCuTixAl1-x(x=0,0.2,0.4,0.6,0.8,1) and CrNiFeCoCuTiy (y-0.5,1,1.5,2.0) high entropy alloys are investigated. Basing on the mature theories of effects of Al element on microstructure and properties of high entropy alloys, Ti element is gradually used to substitute for Al, to study the mechanism of the effects by changing the content of Ti element.The results show that the crystal structures of the alloys transforms from FCC (large)+BCC (small) to FCC+BCC+primary lattice structures with the increase of Ti content. When the content of Ti is oversaturated, the crystal structures change into BCC(large)+FCC (small)+primary lattice structures. With slowly increasing of Ti content, the hardness and strength of CrNiFeCoCuTixAl1-x high-entropy alloys slightly decrease at first, and then return to maximum, and finely have a downward trend. The value of hardness is between526HV and672HV, and the compressive strength value ranges from1628MPa to2347Mpa. When Ti content is increasing rapidly, the hardness of CrNiFeCoCuTiy high-entropy alloys is proportional to Ti content, and the strength is inversely proportional. In other words, the hardness increases with increasing Ti content, and the strength reduces. The hardness value is between637-822HV, and the compressive strength is between1656MPa and2108MPa.With the increase of Ti content, the fracture mode of CrNiFeCoCuTixAl1-x high-entropy alloys convert ductile fracture to cleavage fracture, and CrNiFeCoCuTiy high-entropy alloys from ductile fracture to intergranular fracture. In addition, the corrosion resistance of CrNiFeCoCuTixAl1-x and CrNiFeCoCuTiy high-entropy alloys is enhanced with increasing Ti content.