Microstructure And Mechanical Properties Of Y₃Al₅O₁₂/Al₂O₃ Composite Nanofibers Reinforced Aluminum Matrix Composites

In this study,Y₃Al₅O₁₂/Al₂O₃ composite nanofibers reinforced aluminum matrix composites(Y₃Al₅O₁₂/Al₂O₃ composite nanofibers abbreviated as?YAG/Al₂O₃?_sf)were prepared by vacuum hot pressing sintering technique,where the Y₃Al₅O₁₂/Al₂O₃composite nanofibers were used as the reinforcement.The Y₃Al₅O₁₂/Al₂O₃ composite nanofibers have good mechanical properties were prepared by electrospinning,the interfacial bonding ability between fibers and mtrix becomes superior because of the large specific surface area of the nanofibers,it helps to improve the mechanical properties of composites.Y₃Al₅O₁₂/Al₂O₃ composite nanofibers enhanced the tensile strength of composites while improved the plasticity in the study.The effect of vacuum hot pressing sintering process on the physical and mechanical properties of composites was studied,the best preparation process was determined.According to the variation of mechanical properties of composites with the fibers'addition amount,the best addition amount was determined.The influence of fiber dispersibility on interfacial bonding ability was analyzed,and the influence of interfacial bonding ability on tensile strength and elongation of composites was summarized.The strengthening mechanism of YAG/Al₂O₃ composite nanofibers reinforced matrix composites was investigated,through the the tensile strength increment of the composites by theoretical calculation and combined with the experiment.The specific research results are as follows:1.The?YAG/Al₂O₃?_sf reinforced aluminum matrix composites were successfully prepared by vacuum hot pressing sintering,the effects of process parameters on microstructure and mechanical properties of composites w ere investigated.The composites have the best comprehensive mechanical properties under the conditions of hot pressing sintering temperature of 525?,pressure of 20 MPa and holding for10 minutes.Properly increasing the sintering temperature can promote grain growth and make the microstructure denser,the wetting and bonding ability between the fibers and the matrix was improved.With increasing the pressure can increase the relative density of the composites.Excessive holding time caused grain coarsening and the performance of the composites decreased.2.By studying the effects of?YAG/Al₂O₃?_sf addition amount on the microstructure and mechanical properties of aluminum matrix composites,it was found that when the addition amount of?YAG/Al₂O₃?_sf was 2 wt.%?mass fraction?,the maximum relative density and hardness of the composites reached 98.8%and 120.7HV,respectively.When the addition amount of?YAG/Al₂O₃?_sf was less than 2 wt.%,the fibers have good wettability and dispersibility with the matrix.In the sintering process,the fibers play a role of bridging and hole filling,t he density and hardness of composites were improved.3.The tensile strength and elongation of the composites increased first and then decreased with the addition amount of?YAG/Al₂O₃?_sf from 0 to 5 wt.%.When the addition amount of?YAG/Al₂O₃?_sf was 1 wt.%,the tensile strength and elongation of the composites reached a maximum value,299.1 MPa and 4.3%respectively,which are obviously higher than the matrix of 249.3 MPa and 2.8%.4.The effects of?YAG/Al₂O₃?_sf on load transfer,grain refinement and dislocation propagation caused by thermal matching in the composites were analyzed,the maximum contribution of strength increment caused by load transfer summarized.The pulling/breaking process of?YAG/Al₂O₃?_sff and the plastic deformation of the core-shell structure strengthen and toughen the composites.The core-shell structure of?YAG/Al₂O₃?_sf can hinder crack propagation and improve the tensile strength of composites.According to the comparative analysis of theoretical strength increment and experimental value of composites,the strengthening mechanism in this study was concluded to be mixed strengthening.By analyzing the modified parameters of the second phase strengthening in the mixed strengthening mechanism,the strength increment of the?YAG/Al₂O₃?_sf reinforced aluminum matrix composites can be better predicted.