The main Iimitation to the toughening of the α-Al2O3/Ni composite is the poor bonding atthe interface. which causes the nickel particles to be pulled-out during crack propagation with-out obvious plastic deformation....The main Iimitation to the toughening of the α-Al2O3/Ni composite is the poor bonding atthe interface. which causes the nickel particles to be pulled-out during crack propagation with-out obvious plastic deformation. A proper control of oxygen content at the Al2O3-Ni interfacecan promote wetting at the intedece, and produce a mechanically interlocked and chemically strengthened intedece, causing most of the nickel particles to be stretched to failure and to expe-rience severe plastic deformation during crack propagation in the composite. Fracture toughnesstesting using a modified double cantilever beam method with in situ observation of crack prop-agation in a scanning electron microscope shows that the composite with the strengthenedinterface has a more desirable R-curve behaviour and a higher fracture toughness value than thenormal composite.展开更多
The 6061 aluminum matrix composites reinforced with ZnO-coated Mg_2B_2O_5w were fabricated by squeeze casting method and followed by extruded under a technical equivalent condition. The mechanical properties and micro...The 6061 aluminum matrix composites reinforced with ZnO-coated Mg_2B_2O_5w were fabricated by squeeze casting method and followed by extruded under a technical equivalent condition. The mechanical properties and microstructures of the composites were investigated. The results showed that the elastic modulus of the as-cast composites increased straightly with increasing ZnO coating content. The ultimate tensile strength and yield strength of the as-cast composites rapidly increased initially and then declined with increasing ZnO coating content. However, the elongations of all the as-cast composites had similar values. The elongations of the composites were highly enhanced and the ultimate tensile strength of the composite without ZnO coating was the largest after extrusion. A number of whiskers in the composites with ZnO coating were fractured during the extrusion process, but the whiskers＇ breakage extent was limited with the increase of coating content.展开更多
文摘The main Iimitation to the toughening of the α-Al2O3/Ni composite is the poor bonding atthe interface. which causes the nickel particles to be pulled-out during crack propagation with-out obvious plastic deformation. A proper control of oxygen content at the Al2O3-Ni interfacecan promote wetting at the intedece, and produce a mechanically interlocked and chemically strengthened intedece, causing most of the nickel particles to be stretched to failure and to expe-rience severe plastic deformation during crack propagation in the composite. Fracture toughnesstesting using a modified double cantilever beam method with in situ observation of crack prop-agation in a scanning electron microscope shows that the composite with the strengthenedinterface has a more desirable R-curve behaviour and a higher fracture toughness value than thenormal composite.
基金Project(2011CB612200)supported by the National Basic Research Program of China
文摘The 6061 aluminum matrix composites reinforced with ZnO-coated Mg_2B_2O_5w were fabricated by squeeze casting method and followed by extruded under a technical equivalent condition. The mechanical properties and microstructures of the composites were investigated. The results showed that the elastic modulus of the as-cast composites increased straightly with increasing ZnO coating content. The ultimate tensile strength and yield strength of the as-cast composites rapidly increased initially and then declined with increasing ZnO coating content. However, the elongations of all the as-cast composites had similar values. The elongations of the composites were highly enhanced and the ultimate tensile strength of the composite without ZnO coating was the largest after extrusion. A number of whiskers in the composites with ZnO coating were fractured during the extrusion process, but the whiskers＇ breakage extent was limited with the increase of coating content.
