| Because of the different matrix and reinforcement,the composite can show different properties,and has a wide range of applications,so it has attracted the attention of researchers.B4CP/Al composite has high strength,low density and can absorb neutrons,so it plays an important role in transportation,national defense industry,nuclear waste transportation and storage,In this paper,the ultra-high strength B4CP/Al composite with strength of 1172MPa has been successfully designed and prepared by using the Al-Zn-Mg-Cu alloy powder independently designed and prepared by the research group as the matrix and the B4CP with particle size of 1?m as the reinforcement,and used SEM,OM,XRD and other equipment to study the ball milling powder,argon protection sintering/hot isostatic pressing sintering,hot extrusion,solution aging and other preparation and processing technology and material organization properties.The detailed research contents and results are as follows:?1?The reinforcement system of B4CP/Al composite was designed and its preparation process was studied.The results show that the reinforcers in the composite powders obtained by ball milling method of wet grinding reinforcers?B4CP,Tip?-mixed wet grinding reinforcers and matrix dry grinding mixed powders are uniformly dispersed.When the sintering temperature is lower than 750?,with the increase of sintering temperature,the content of Zn decreases,the density and hardness of the composite increase.When the sintering temperature is higher than 800?,the content of Zn,the hardness and the density of the composite decrease sharply.The maximum hardness of the composite was 206.93hv at 950?.After two times of high temperature sintering,the oxide layer on the surface of the composite was destroyed,and the hardness of the material decreased.After four times of high temperature sintering,the material was loose,the surface was a large amount of Al rich phase,and the hardness of the material decreased to 86.94 HV.?2?The effect of secondary argon protected sintering on the microstructure and properties of B4CP/Al composite was studied.The results show that the hardness of the composite can be improved by low temperature pre sintering.At the temperature of950?,with the increase of pre sintering temperature,the density of the composite decreases gradually.The hardness of the composite increases first and then decreases.At the temperature of 640?,the hardness of the composite is 192.81 HV and the density is 82.04%.For the preparation of B4CP/Al Composite by secondary argon protected sintering,the density and Zn content of the composite decreased,and the hardness of the material decreased first and then increased when the temperature was increased at 640?.When the sintering temperature is 750?,the comprehensive properties of the material are the best.At this time,the hardness is 208.34 HV,the density is 87.41%,and the content of Zn element is 8.59 wt.%.With the increase of annealing temperature and time,the hardness and compressive strength of aluminum matrix composites prepared by two-step argon protected sintering?640?pre sintering+950?re sintering?-hot extrusion decreased.After annealing at 200?×2h,the hardness,compressive strength and fracture strain of the composite were 293.9 HV,984.04 MPa and 7.31%,respectively.?3?The effect of solution aging process on the microstructure and properties of extruded aluminum matrix composites?pre sintered at 640?and re sintered at 750??was studied.The results show that the conductivity of the material decreases and the fracture strain increases with the increase of solution temperature.At 475?,the conductivity is 14.26%IACS and the fracture strain is 6.9%.When the solid solution temperature was 485?,some tissues of the material were over-burned,and the hardness and compressive strength were 278.86 HV and 818.06 MPa,respectively.After hot extrusion-G1 solution?455?×2h+465?×2h+475?×2h?-T6-1?121?×5h?aging,the comprehensive mechanical properties are the best.At this time,the hardness of the material is 337.93 HV,the conductivity is 13.14%IACS,the compressive strength is 1172.41MPa,and the fracture strain is 7.54%,.?4?The microstructure and properties of sintered B4CP/Al composite prepared by hot isostatic pressing were studied,and its solution aging process was explored.The results show that the hardness and compressive strength of the sintered aluminum matrix composites are 287.08hv and 536.85mpa respectively after solution of S1?455?×2h+465?×2h?.When the aging time is prolonged,the hardness and compressive strength of the material increase.When A2 aging?121?×3.5h?water quenching?+65?×48h+121?×1.5h?,the comprehensive properties of the material are the best.At this time,the hardness and compressive strength of the material are 308.26 HV and716.49MPa respectively.After S2 solution?455?×2h+465?×2h+475?×2h?,the electrical conductivity and fracture strain decreased,the hardness and strength of the material increased first and then decreased,and the comprehensive properties of the composite after A3 aging?100?×4.5h?were the best.At this time,the hardness,pressure resistance and fracture strain of the material were 319.06 HV,715.12 MPa and5.6%,respectively.In this paper,the ultra-high strength aluminum matrix composite with strength of1172MPa and fracture strain of 7.54%was prepared by powder metallurgy?two times argon protection sintering,hot isostatic pressing sintering?-plastic deformation?hot extrusion?-heat treatment?solution aging?process with 7000 series ultra-high strength aluminum alloy as the matrix and B4CP as the reinforcement,which completed the effective adjustment of the material preparation process parameters and performance.This has not been reported at home and abroad. |
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