Investigation On Preparation,processing,microstructure And Properties Of FeCoNi_1.5CrCu High Entropy Alloy Particles Reinforced 2024Al Matrix Composites

In this paper,15wt.%FeCoNi_1.5Cr Cu/2024Al composites were prepared by microwave sintering,and the influence of microwave sintering parameters on the microstructure and mechanical properties of FeCoNi_1.5Cr Cu/2024Al composites were studied,and the suitable microwave sintering parameters were optimized.The FeCoNi_1.5Cr Cu/2024Al composites were prepared with the optimal sintering parameters as the rolling base material,and the effect of hot rolling parameters on the structure and properties of the composites were studied.Through the analysis on microstructure,phase,density and element distribution characteristics of composites by SEM,EDS,TEM,XRD,Archimedes principle and other detection methods,the microwave sintering mechanism and effect of hog rolling on the microstructure of high-entropy alloy particles reinforced aluminum matrix composites are revealed.The micro/macro mechanical properties of microwave-sintered and as-rolled composites were analyzed by nano-indentation,micro-hardness,compression and tensile electronic universal testing machine,et al,and the relationship between the micro/macro mechanical properties and microstructure are discussed.Especially,the influence of HEA/Al interfacial bonding on the microstructure an properties is focused.The main findings are as follows:(1)Through the research on the microstructure of FeCoNi_1.5Cr Cu/2024Al composites prepared with different microwave sintering time,it is found that with the extension of sintering time,FeCoNi_1.5Cr Cu high-entropy alloy particles are first uniformly distributed in the 2024Al matrix and then agglomerated.On the condition of optimized 40 min sintering time,the high-entropy alloy particles are uniformly distributed,and the average particle size is the smallest,only 2.92?m.At this time,there is an ID layer between the HEA particles and the matrix.The high-density dislocations surround the interface of the HEA/2024Al composite with a width of80?120nm.HEA reinforced particles and matrix have good interfacial wettability and interfacial compatibility,which significantly improves the strength and toughness of composites.(2)By the research on the micro-nano mechanical properties and macro-mechanical properties of FeCoNi_1.5Cr Cu/2024Al composites prepared with different microwave sintering time,it is found that,for the 40min sample,the compressive strength,yield strength and microhardness of the composites reach the maximum values as 248.7 MPa,227.4 MPa and 93.1 HV.Correspondingly,the micro-nano mechanical properties show that the HEA particles in the composites exhibit the highest hardness and elastic modulus as 3893.2 MPa and 100.82 GPa,respectively.Therefore,FeCoNi_1.5Cr Cu high-entropy alloy particles as the reinforcement of the 2024 aluminum matrix composites can better bear the main stress;and at this time,the interfacial hardness and elastic modulus are 1331.1 MPa and 47.544 GPa,reaching the maximum parameter,which plays an important role in the load transfer from the matrix to the reinforced particles.(3)The FeCoNi_1.5Cr Cu/2024Al composites prepared with optimized sintering parameters was used as the base material,and the influence of different rolling deformation amounts on the microstructure of the composites were studied.When the deformation amount is 62.5%,the grain refinement effect of the reinforcement phase is obvious.The reinforcement phase of high-entropy alloy particles are uniformly distributed in the matrix along the rolling direction,and the large-size particles have basically disappeared.The dispersion and orientation of the reinforcements have been improved,which shows a good rolling structure characteristic.In the process of hot rolling,when the deformation amount increases along the 25%?37.5%?50%?62.5%?75%,the crystal grains of the matrix are mainly oriented along the(111),(200)and(220)crystal planes.The diffraction peak intensity of HEA for(111),(200)and(220)crystal planes show a trend of first increasing and then decreasing,which arrives at utmost in 62.5%sample.Besides,the diffraction peak intensities of(311)and(322)crystal planes are relatively high that exhibits a certain preference.They show a trend of continuous increase with the enhancement of deformation amount.(4)The study has proceeded on the influence of rolling deformation amount on the micro-nano mechanical properties and macro-mechanical properties of composites,and the results found that:with the increase of rolling deformation amount,the tensile strength of the hot-rolled composites show a trend as first great increase then slow increase;while the elongation rate presents the characteristics of a rapid decrease first then a slow decrease.On the optimal condition of 62.5%deformation amount,the tensile strength and elongation of the hot-rolled composites are 173.54MPa and12.93%respectively.The micro-nano mechanical properties show that hot rolling can significantly improve the micro-nano hardness and elastic modulus of the matrix,reinforcement,and interface.For 62.5%sample,the hardness and elastic modulus of the matrix reach 911.18 MPa and 94.29 GPa respectively,which are 39.4%and 77.6%higher than the base metal,indicating that rolling has a significant effect on improving the mechanical properties of the matrix.The micro-nano hardness at the interface reaches 1715 MPa,increase of 28.8%compared with the corresponding value of1331.1 MPa for the base material,indicating that rolling has a strengthening effect on the interface of the composites and helps to exert the interfacial strengthening.The maximum micro-nano hardness and elastic modulus of the high-entropy alloy particles reach 6356.1 MPa and 174.81 GPa separately,which further strengthens the ability to bear the principal stress.