The in situ synthesized MoSi2-SiC composite is proved to be of higher fracture toughness than the monolithic MoSi2. The TEM and HREM study reveals that the interface between MoSi2/SiC is of direct atomic bonding witho...The in situ synthesized MoSi2-SiC composite is proved to be of higher fracture toughness than the monolithic MoSi2. The TEM and HREM study reveals that the interface between MoSi2/SiC is of direct atomic bonding without any amorphous glassy phase, such the SiO2 structure. Based on the fractography and the observation of crack propagation path from indentation, it is concluded that the toughening of such composite at room temperature can be attributed to the high interfacial binding energy, the refinement of the MoSi2 matrix and the deflection and bridging behavior in the crack propagation.展开更多
In situ synthesized MgAl2O4whiskers reinforced 6061 Al alloy composites were fabricated by a powder metallurgy method.Nano-sized MgAl2O4spinel whiskers distributed uniformly in 6061 Al alloy matrix without any interfa...In situ synthesized MgAl2O4whiskers reinforced 6061 Al alloy composites were fabricated by a powder metallurgy method.Nano-sized MgAl2O4spinel whiskers distributed uniformly in 6061 Al alloy matrix without any interfacial product and laid along the extrusion direction after hot extrusion.As-extruded composite samples were annealed at 530,580,600 and 630℃for 1 h and examined by electron backscattered diffraction to investigate the recrystallization behavior of obtained composites.Microstructure and texture evolution was investigated,and it is found that the recrystallization process is inhibited by whiskers because of Zener pinning.Slender fibrous grains remain until 630℃,and deformation textures still exist even in specimen annealed at 630℃.Hardness and tensile tests show that the completely recrystallized sample has an ultimate tensile strength of 218 MPa and a hardness of HV52 compared with 283 MPa and HV 69 of the unannealed sample.Mechanical properties of the annealed samples decline slightly with annealing temperature increasing up to 600℃.展开更多
基金the National Natural Science Foundation of China (No. 59895150-04-02).
文摘The in situ synthesized MoSi2-SiC composite is proved to be of higher fracture toughness than the monolithic MoSi2. The TEM and HREM study reveals that the interface between MoSi2/SiC is of direct atomic bonding without any amorphous glassy phase, such the SiO2 structure. Based on the fractography and the observation of crack propagation path from indentation, it is concluded that the toughening of such composite at room temperature can be attributed to the high interfacial binding energy, the refinement of the MoSi2 matrix and the deflection and bridging behavior in the crack propagation.
基金financially supported by the National Natural Science Foundation of China(No.51571147)。
文摘In situ synthesized MgAl2O4whiskers reinforced 6061 Al alloy composites were fabricated by a powder metallurgy method.Nano-sized MgAl2O4spinel whiskers distributed uniformly in 6061 Al alloy matrix without any interfacial product and laid along the extrusion direction after hot extrusion.As-extruded composite samples were annealed at 530,580,600 and 630℃for 1 h and examined by electron backscattered diffraction to investigate the recrystallization behavior of obtained composites.Microstructure and texture evolution was investigated,and it is found that the recrystallization process is inhibited by whiskers because of Zener pinning.Slender fibrous grains remain until 630℃,and deformation textures still exist even in specimen annealed at 630℃.Hardness and tensile tests show that the completely recrystallized sample has an ultimate tensile strength of 218 MPa and a hardness of HV52 compared with 283 MPa and HV 69 of the unannealed sample.Mechanical properties of the annealed samples decline slightly with annealing temperature increasing up to 600℃.
