Study On Composition Design,microstructure And Properties Of High Entropy Alloys With High Density And High Plasticity

With the development of anti-armor technology and industrial application,it is difficult for traditional shaped charge liner?SCL?materials represented by pure copper to meet the high demand of penetration performance in related fields.So,it is urgent to develop new SCL materials.High entropy alloys?HEAs?not only subverts the traditional alloy design philosophy,but also keeps making breakthroughs in material properties,showing a great potential to replace traditional materials in a variety of fields,and SCL is one of them.According to the unique design idea and excellent performance of HEAs,if HEAs with high density and high plasticity can be developed as SCL material,a new way can be explored for the penetration improvement of SCL.In this paper,high-density Ta/Mo elements were added into single-phase FCC matrix alloy,and CoCuFeNiTa_x,CoCu_0.5FeNiTa_x,CoFeNiTa_x,CoFeNiTa_0.1Mo_x,four series of 24 HEAs compositions with possible high density and high plasticity were designed based on valence electron concentration and theoretical density.By X-ray diffractometer,scanning electron microscope,universal testing machine and other analysis and testing methods,the microstructure,mechanical properties,magnetic properties and comprehensive properties of the above cast samples were analyzed in this paper.The main findings are as follows:?1?With the increase of Ta/Mo content,the four series of HEAs all changes from single-phase FCC structure to dual-phase structure composed of FCC and Laves phase.Cu segregation commonly exists in the microstructure of CoCuFeNiTa_x HEAs,and the morphology of Laves phase changes from reticular to reticular+dendritic to reticular+massive.The microstructure of CoCu_0.5FeNiTa_x HEAs changes from single-phase solid solution to hypoeutectic to nearly eutectic to hypereutectic morphology.The microstructure of CoFeNiTa_x and CoFeNiTa_0.1Mo_x HEAs changes from single-phase solid solution to hypoeutectic morphology.?2?With the increase of Ta/Mo content,the yield strength and Vickers hardness of the four-series HEAs gradually increase,while the plasticity gradually deteriorates.Among them,CoCuFeNiTa_x?x=0.1-0.2?,CoCu_0.5FeNiTa_x?x=0.1-0.2?,CoFeNiTa_x?x=0.1-0.2?and CoFeNiTa_0.1Mo_x?x=0-0.5?as a total of 11 HEAs compositions show both high density and high plasticity,which completely or nearly meet the requirements of??8.94 g/cm³,?_c>50%,?>5%.Besides,these HEAs have low coercivity and high saturation magnetization at the same time,showing excellent soft magnetic performance.?3?HEAs with single-phase FCC structure,high density and high plasticity can be obtained by adding metal elements with high density into HEAs with moderate density and single-phase FCC structure,then designing the addition content by VEC?8 and?>0.96.