Effects Of Solidification Cooling Rate And Heat Treatment On Microstructure And Magnetic Properties Of FeCoNiAlSi High Entropy Alloy

In recent years,high-entropy alloys(HEAs)have always been a hot spot for researchers.Compared with traditional alloys,HEAs have many excellent properties.These excellent properties are not only reflected in mechanical properties,but also in functional properties.There are many good performances:such as magnetic properties,electrochemical properties,showing the broad application prospects of this material.In this project,(Co₃₀Fe₄₅Ni₂₅)_0.83(Al40Si60)0.17 HEAS with good soft magnetic properties were selected as the object to systematically study the influence mechanism of cooling rate during solidification process on its microstructure and properties.In addition,the effect of heat treatment on its microstructure and properties was further studied.The specific conclusions are as follows:1.The cooling rate has little effect on the phase structure of(Co₃₀Fe₄₅Ni₂₅)_0.83(Al40Si60)0.17HEAs.The samples are all FCC+BCC dual-phase structure.With the increase of cooling rate,the solidification structure size gradually becomes smaller,and at the same time tends to be order and homogenization;2.As the cooling rate increases,the microhardness of the alloy increases from 487.7HV to 538.4HV,a maximum increase of 10.4%;corrosion resistance is also enhanced,which is related to the formation of surface Al oxides and the uniformity of the structure;The soft magnetic performance is improved,and the 2mm sample has the best soft magnetic performance,Ms=141.1 emu/g,Hc=8.6 Oe;3.After annealing treatment of(Co₃₀Fe₄₅Ni₂₅)_0.83(Al40Si60)0.17HEAs,the phase structure is still the solid solution of FCC and BCC structure,the dendrites are coarsened,the alloying elements are more evenly distributed in the matrix,and the element segregation is reduced;4.After the annealing treatment,the hardness value of the alloy changes.The hardness value of the sample after the 300? treatment is the highest,which is 537 HV,which is an increase of 9.8%compared to the original sample;the Ms value of the sample after the 300? annealing treatment is the highest,which is 122.94 emu/g;After the original sample is annealed at 400?,He is reduced to the lowest value,10.1 Oe,heat treatment can effectively reduce the coercivity.