Research On Directional Solidification Structure Evolution And Properties Of Binary Cu-Ce And Multicomponent CoCrFeNiCuTi_0.8Alloy

As an important technology,directional solidification technology has successfully developed a series of alloys with excellent properties such as DZ471G nickel-based superalloys,YBCO high-temperature superconductors and Cu-Cr composite materials.The directional solidification technology is widely used in the preparation of aeroengine turbine blades and magnetic materials and other functional materials,providing great support for solidification theory research.In this study,binary and multi-component copper alloys were selected as the research objects.Cu-21%Ce,CuCe,CoCrFeNiCuTi_0.8 alloys were prepared in the range of solidification rate from 2μm/s to 500μm/s using directional solidification technology.Discuss the effect of directional solidification technology on microstructure evolution and mechanical properties of different alloy systems.The study found that when the solidification rate is 2μm/s,4μm/s,and 5μm/s,the structure of the hyper-peritectic Cu-21%Ce alloy exhibits a typical island structure due to the competitive growth caused by the presence of the peritectic reaction.When the solidification rate is greater than 5μm/s,it transforms into a dendrite structure.As the solidification rate increased from 5μm/s to 100μm/s,the solidification structure of CuCe alloy changed from a cellular to a dendrite.And at 10μm/s,a two-phase symbiotic structure of primary phase and peritectic phase was observed,which is called cellular peritectic coupling growth.The directional solidification structure of CoCrFeNiCuTi_0.8 high-entropy alloy was dendrite in the range of 5μm/s to 500μm/s.And when the solidification speed is greater than 50μm/s,the growth of secondary dendrite arms occurs.Through quantitative analysis of the solidification structure,it is found that with the increase of the solidification speed,the primary dendrite spacing,dendrite size,and primary phase volume fraction of the three alloys decrease,the fractal dimension of the dendrite increases,and the number of nearest neighbors is closer to 6.Directional solidification technology can refine the solidification structure of binary Cu-Ce alloy and multicomponent CoCrFeNiCuTi_0.8 high-entropy alloy,and improve the compression properties of these three alloys.The study found that directional solidification technology can reduce the primary dendrite spacing of binary Cu-Ce alloy and multi-component CoCrFeNiCuTi_0.8 high-entropy alloy,and obtains a denser and more uniform dendrite array.At the same time,the proportion of each phase can be adjusted to obtain the best performance of each phase.The directional solidification technology can improve the binary Cu-Ce alloy and the multicomponent CoCrFeNiCuTi_0.8 high-entropy alloy by controlling the solidification rate.At a solidification rate of 6μm/s,the content of hard dendrite phase in Cu-21%Ce alloy is 45.16%,so the maximum compressive strength is270 Mpa.The CuCe alloy has a unique cellular peritectic coupling growth structure at 10μm/s,so the compressive strength and compressive strain reached the peak value（266 MPa and 4.83%）.When the solidification rate was 500μm/s,the compressive strength of the multi-component CoCrFeNiCuTi_0.8 high-entropy alloy reached 1449.8 Mpa and the maximum compressive strain was 12.75%.For example,the solidification structure can be optimized,and each phase can be adjusted to improve its mechanical properties.