Porous Ni3Al intermetallics were fabricated by elemental powder reactive synthesis method, using carbamide powders as space holders. Corrosion behavior of porous Ni3Al intermetallics was investigated in a 6 mol/L KOH ...Porous Ni3Al intermetallics were fabricated by elemental powder reactive synthesis method, using carbamide powders as space holders. Corrosion behavior of porous Ni3Al intermetallics was investigated in a 6 mol/L KOH solution using electrochemical methods and immersion test. Effect of porous structures on the corrosion behavior of the porous Ni3Al intermetallics was studied. The results indicate that the porous Ni3Al intermetallics with higher porosities suffer more serious corrosion than the ones with lower porosities because the complicated interconnected porous structures and the large true surface areas exist in the samples with a higher porosity. But the corrosion rates of the porous Ni3Al intermetallics are not proportional to the true surface areas. The reason is that the pore size, pore size distribution and pore shape of the porous Ni3Al intermetallics change with the increasing porosity. All the porous Ni3Al intermetallics with different porosities exhibit excellent corrosion resistance in a strong alkali solution.展开更多
The effects of Mn addition (1 wt.%, 2 wt.% and 4 wt.%) and friction stir processing (FSP) on the microstructure and mechanical properties of Al-4Ni alloy were studied. The results showed that Mn promoted the formation...The effects of Mn addition (1 wt.%, 2 wt.% and 4 wt.%) and friction stir processing (FSP) on the microstructure and mechanical properties of Al-4Ni alloy were studied. The results showed that Mn promoted the formation of Al6Mn and Al60Mn11Ni4 intermetallics. These Mn-rich compounds increased the strength and hardness, but decreased the ductility and fracture toughness of the alloy. To improve the ductility and toughness, the as-cast alloys were then subjected to FSP (rotation speed of 1600 r/min and traverse speed of 12 mm/min). According to the results, FSP greatly improved the mechanical properties. The tensile strength, yield strength, fracture strain, microhardness, and fracture toughness of FSPed Al-4Ni-2Mn increased by 67%, 30%, 230%, 20%, and 1185%, respectively. The fine redistribution of Mn-rich compounds, formation of ultrafine grains, microstructural densification, and the elimination of casting defects such as micropores and oxide bifilms were found to be the most important factors responsible for improving the mechanical properties. The fractographic investigations also revealed that the fracture of as-cast Mn-rich alloys changed from the brittle mode containing micro-facets to a more ductile fracture mode containing fine and equiaxed dimples in FSPed alloys.展开更多
基金The authors are grateful for the financial support of the Postdoctoral Science Foundation of China, the Prior Research Foundation of Key Laboratory of High Energy Density Beam Processing Technology of China.
基金Project(2009CB623406)supported by the National Basic Research Program of ChinaProject(12JJ4044)supported by the Natural Science Foundation of Hunan Province,ChinaProject(13C902)supported by the Scientific Research Fund of Hunan Provincial Education Department,China
文摘Porous Ni3Al intermetallics were fabricated by elemental powder reactive synthesis method, using carbamide powders as space holders. Corrosion behavior of porous Ni3Al intermetallics was investigated in a 6 mol/L KOH solution using electrochemical methods and immersion test. Effect of porous structures on the corrosion behavior of the porous Ni3Al intermetallics was studied. The results indicate that the porous Ni3Al intermetallics with higher porosities suffer more serious corrosion than the ones with lower porosities because the complicated interconnected porous structures and the large true surface areas exist in the samples with a higher porosity. But the corrosion rates of the porous Ni3Al intermetallics are not proportional to the true surface areas. The reason is that the pore size, pore size distribution and pore shape of the porous Ni3Al intermetallics change with the increasing porosity. All the porous Ni3Al intermetallics with different porosities exhibit excellent corrosion resistance in a strong alkali solution.
文摘The effects of Mn addition (1 wt.%, 2 wt.% and 4 wt.%) and friction stir processing (FSP) on the microstructure and mechanical properties of Al-4Ni alloy were studied. The results showed that Mn promoted the formation of Al6Mn and Al60Mn11Ni4 intermetallics. These Mn-rich compounds increased the strength and hardness, but decreased the ductility and fracture toughness of the alloy. To improve the ductility and toughness, the as-cast alloys were then subjected to FSP (rotation speed of 1600 r/min and traverse speed of 12 mm/min). According to the results, FSP greatly improved the mechanical properties. The tensile strength, yield strength, fracture strain, microhardness, and fracture toughness of FSPed Al-4Ni-2Mn increased by 67%, 30%, 230%, 20%, and 1185%, respectively. The fine redistribution of Mn-rich compounds, formation of ultrafine grains, microstructural densification, and the elimination of casting defects such as micropores and oxide bifilms were found to be the most important factors responsible for improving the mechanical properties. The fractographic investigations also revealed that the fracture of as-cast Mn-rich alloys changed from the brittle mode containing micro-facets to a more ductile fracture mode containing fine and equiaxed dimples in FSPed alloys.
