Study On Preparation And Mechanical Properties Of AlCoCrFeNiSi High Entropy Alloys

High-entropy alloys（HEAs）or multi-primary alloys（MPEAs）,has attracted widespread attention.These alloys have many unique properties such as high hardness,excellent temper softening resistance,good wear resistance,unique oxidation resistance,high corrosion resistance and soft magnetic properties,all of which make high entropy alloys interesting novel materials.HEAs are usually composed of five or more main elements,each of which has an atomic percentage of between 5%and 35%.HEAs have important significance in coatings preparation and application of bulk alloys due to their excellent mechanical properties.At the same time,a new theme of designing alloy components to achieve specific properties has become a research hotspot.In this work,high-entropy alloy coatings were prepared by plasma spraying technology and laser re-melting.As-cast high-entropy alloys were prepared by vacuum arc melting furnace.The A1_xCoCrFeNiSi HEAs with different Al content and A1CoCrFeNiSi_x HEAs with different Si content were studied,which were analyzed by XRD,SEM,EDS,3D measuring laser microscope.The effects of Al and Si content on the phase composition and microstructure of the alloy were invesgated,and the hardness and wear resistance of each alloy were tested.The results show that:Al promotes the formation of BCC phase in A1_xCoCrFeNiSi HEAs.Its structure is transformed from BCC and FCC phase and a small amount of intermetallic compounds to BCC phase and a small amount of intermetallic compounds.The structure exhibits a transition between the petal and the ring shape.Nano-precipitate structure also formate of as-cast alloys.With the increase of Si content,the phase structure changes from FCC and BCC phase to BCC phase,and the intermetallic copound Cr₃Si phase is formed of AlCoCrFeNiSi_x alloy.Its structure is a network.It is the same to as-cast A1_xCoCrFeNiSi HEAs,which also have the formation of nano-precipitates.With the increase of Al content and Si content,the hardness is improved of A1_xCoCrFeNiSi HEAs and AlCoCrFeNiSi_x HEAs.The hardness value（1100HV-1255HV）is higher than that of the vacuum arc melting（about 900HV）.The results of wear test prove that these two elements improve the wear resistance of the coatings and the alloys.The friction coefficient is gradually reduced,and the depth of wear can be observed to be shallow gradually,and the wear mechanism is abrasive wear.