Effect Of Solidification Cooling Rate And Rolling On Microstructure And Properties Of FeCoNi?CuAl?_0.8 Soft Magnetic High Entropy Alloy

High Entropy Alloys?HEAs?,as a new kind of alloy material,has different phase forming rules and excellent properties from traditional alloy due to its unique microstructure and design concept,such as high strength,high hardness,good electromagnetic properties and thermal stability.These excellent performances make HEAs widely used in aerospace,electromagnetic communication and other fields.At present,the research of HEAs mainly focuses on the addition of elements,preparation process and heat treatment,but the complex formation mechanism of HEAs leads to the unclear relationship between its microstructure and performance.Therefore,it is of great value to investigate the relationship between microstructure,mechanical properties and magnetic properties of HEAs.In this thesis,the effect of solidification cooling rate and cold rolling on the microstructure and magnetic properties of FeCoNi?CuAl?_0.8 HEAs was studied.In addition,the effect of heat treatment on the microstructure and magnetic properties of FeCoNi?CuAl?_0.8.8 HEAs with different deformation was studied by the combination of casting simulation software and experiments.The following conclusions were drawn:1.Different cooling rates have little effect on the phase structure of FeCoNi?CuAl?_0.8 HEAs.With the increase of cooling rate,the dendrite morphology has a continuous change from columnar to fine equiaxed and then to columnar,and the grains are continuously refined.In the TEM image,it is observed that the increase of cooling rate increases the atomic stacking density of the sample.With the increase of cooling rate,Ms of 2 mm sample increased from 77.4 emu/g to 81.5 emu/g,and the overall increase was 6%.2.After cold rolling treatment,the phase structure of the sample is still FCC and BCC solid solution.The microhardness of the sample increases monotonously from303.14 HV to 414.88 HV with the increase of shape variable,and the overall increase is 36.9%.After rolling at 15%reduction,Ms was increased,at the same time,the dislocation density and lattice distortion of the sample are increased and the order degree of the domain is reduced by cold rolling treatment.3.After annealing,the Ms of the original sample was increased to 78.87 emu/g by13.3%,and the Ms of the 15%deformation sample was increased to 82.9 emu/g by18.7%,the mainly reason is the change of solid solution structure and influence of the recovery.