Effect Of Nano-phase SiC/TiC Addition On Microstructures And Properties Of Al-Cr-Fe-Ni High Entropy Alloys

With the continuous development of science and technology,the requirements for the properties of materials are also improved constantly.High entropy alloy is a solid solution alloy with simple crystal structure,which is composed of multiple principal elements with equal or near equal molar ratio.As a novel alloy,it is one of the most promising structural materials in the future because of its excellent properties.Ceramic phases are often used to improve the properties of alloys due to their high hardness and high strength.In this paper,Al_xCrFe₂Ni₂?x=0.6,1.4?high entropy alloys with different SiC/TiC addition were prepared by vacuum arc melting furnace.The microstructures and properties of single FCC phase Al_0.6CrFe₂Ni₂ high entropy alloyand single BCC phase Al_1.4CrFe₂Ni₂ high entropy alloy with different SiC/TiC content were investigated by phase analysis,microstructure observation,stress-strain curve test and hardness test.The results show that the addition of SiC does not change the original phase structure of Al_xCrFe₂Ni₂ high entropy alloys.Due to the decomposition of SiC at high temperature,the C is combined with Cr to form the reinforce-phase Cr₇C₃.With the increasing amount of SiC,the content of Cr₇C₃ phase in the alloy also increases and the size of Cr₇C₃ phase grows gradually.For SiC/Al_0.6CrFe₂Ni₂ highentropy alloys,when the added SiC content is 2.5vol%,SiC/Al_0.6CrFe₂Ni₂ high entropy alloy had better comprehensive properties,the yield strength and hardness were 618MPa,251HV,respectively;For SiC/Al_1.4CrFe₂Ni₂ high entropy alloys,when the added SiC content is 2.5vol%,SiC/Al_1.4CrFe₂Ni₂ high entropy alloy has better comprehensive properties,the yield strength,compressive strength,plasticity and hardness are1557MPa,3136MPa,35.03%and 487HV,respectively.The addition of TiC also does not change the original phase structure of Al_x CrFe₂Ni₂ high entropy alloys.With the addition of Ti C,TiC appears on the grain boundaries and the size of grain boundaries increase with the addition of Ti C.TiC phase plays a role of grain-boundary strengthening,which increases the strength of the alloys.When the TiC addition amount is2.5vol%,TiC/Al_0.6CrFe₂Ni₂ high entropy alloy has better comprehensive properties,the yield strength and hardness are 577MPa and 244HV,respectively;for TiC/Al_1.4CrFe₂Ni₂ high entropy alloys,2.5TiC/Al1.4 alloy has better comprehensive properties,the yield strength,compressive strength,plasticity and strength are 1576MPa,3224MPa,39.78%and 4408HV,respectively.