2024Al based composites reinforced by a hybrid of SiC whisker and SiC nanoparticle were fabricated by a squeeze casting route. In the (SiCw+SiCp)/Al composites, the volume fraction of SiC whisker is 20% and that of Si...2024Al based composites reinforced by a hybrid of SiC whisker and SiC nanoparticle were fabricated by a squeeze casting route. In the (SiCw+SiCp)/Al composites, the volume fraction of SiC whisker is 20% and that of SiC nanoparticle is 2%, 5% and 7%, respectively. The as cast composites were solution treated followed by aging treatment. The experimental results show that the SiC nanoparticles are more effective in improving the hardness and tensile strength of the composites than SiC whiskers. The hardening kinetics of the composites is enhanced by reinforcements addition and the peak aging time is 4-5 h. The hardness of all the hybrid composite decreases at the initial aging stage, suggesting that dislocation recovery softening process coexists with precipitation hardening. DSC study shows that the GP zone formation of the hybrid composites is suppressed.展开更多
The precipitation and grain growth behavior during isothermal treatment of hot extruded alloy 718 was investigated. It is found that the hardness of the hot extruded alloy 718 increases with holding time at 600～700 ...The precipitation and grain growth behavior during isothermal treatment of hot extruded alloy 718 was investigated. It is found that the hardness of the hot extruded alloy 718 increases with holding time at 600～700 ℃, but slightly decreases at 800 ℃. When the exposure temperature reaches above 900 ℃, a rapid decrease in hardness of alloy 718 occurs before the holding time of 0.3 h. Above the δ solvus temperature, γ ′ and γ ″ phases are dissolved directly into the matrix without δ precipitation, resulting in a rapid grain growth.展开更多
Several orthogonal cutting experiments were carried out on SiC reinforced aluminium composites. In the cutting process, photos of the chip bottom specimen SEM were gotten with the aid of ‘quick stop tool device’. Ac...Several orthogonal cutting experiments were carried out on SiC reinforced aluminium composites. In the cutting process, photos of the chip bottom specimen SEM were gotten with the aid of ‘quick stop tool device’. According to the photos, the build up edge (BUE) can be produced in circumferential cutting experiments. In comparison with carbon steel BUE, aluminium composites BUE is like a wedge in shape, and its development mechanism is mechanical enchasing other than "cold welding". In addition to the above mentioned conclusions, the minishing BUE height H b is also analyzed.展开更多
基金Project(50071018) supported by the National Natural Science Foundation of China
文摘2024Al based composites reinforced by a hybrid of SiC whisker and SiC nanoparticle were fabricated by a squeeze casting route. In the (SiCw+SiCp)/Al composites, the volume fraction of SiC whisker is 20% and that of SiC nanoparticle is 2%, 5% and 7%, respectively. The as cast composites were solution treated followed by aging treatment. The experimental results show that the SiC nanoparticles are more effective in improving the hardness and tensile strength of the composites than SiC whiskers. The hardening kinetics of the composites is enhanced by reinforcements addition and the peak aging time is 4-5 h. The hardness of all the hybrid composite decreases at the initial aging stage, suggesting that dislocation recovery softening process coexists with precipitation hardening. DSC study shows that the GP zone formation of the hybrid composites is suppressed.
文摘The precipitation and grain growth behavior during isothermal treatment of hot extruded alloy 718 was investigated. It is found that the hardness of the hot extruded alloy 718 increases with holding time at 600～700 ℃, but slightly decreases at 800 ℃. When the exposure temperature reaches above 900 ℃, a rapid decrease in hardness of alloy 718 occurs before the holding time of 0.3 h. Above the δ solvus temperature, γ ′ and γ ″ phases are dissolved directly into the matrix without δ precipitation, resulting in a rapid grain growth.
文摘Several orthogonal cutting experiments were carried out on SiC reinforced aluminium composites. In the cutting process, photos of the chip bottom specimen SEM were gotten with the aid of ‘quick stop tool device’. According to the photos, the build up edge (BUE) can be produced in circumferential cutting experiments. In comparison with carbon steel BUE, aluminium composites BUE is like a wedge in shape, and its development mechanism is mechanical enchasing other than "cold welding". In addition to the above mentioned conclusions, the minishing BUE height H b is also analyzed.
