Ultra-high strength Al alloy system was developed by cryorolling and the contribution of various strengthening mechanisms to the overall yield strength of the system was evaluated. Cryorolling of Al-4%Cu-3%TiB2 in sit...Ultra-high strength Al alloy system was developed by cryorolling and the contribution of various strengthening mechanisms to the overall yield strength of the system was evaluated. Cryorolling of Al-4%Cu-3%TiB2 in situ composite followed by short annealing at 175 ℃ and ageing at 125℃ resulted in an ultra-high yield strength of about 800 MPa with 9%total elongation. The strengthening contributions form solid solution strengthening, grain refinement, dislocation strengthening, precipitation hardening and dispersion strengthening were evaluated using standard equations. It was estimated that the maximum contribution was from grain refinement due to cryorolling followed by precipitation and dispersion strengthening.展开更多
The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and th...The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.展开更多
SiC foam ceramic reinforced aluminum matrix composites(SFCAMCs)were prepared by squeeze casting aluminum alloy(Al-23Si)into the SiC foam ceramic with different pore sizes,and the corrosion behavior of the SFCAMCs was ...SiC foam ceramic reinforced aluminum matrix composites(SFCAMCs)were prepared by squeeze casting aluminum alloy(Al-23Si)into the SiC foam ceramic with different pore sizes,and the corrosion behavior of the SFCAMCs was studied in NaCl solutions.Static immersion corrosion tests were conducted at 20°C,50°C and 80°C,respectively.Corrosion morphology and products were analyzed by scanning electron microscope,energy dispersive system and X-ray diffraction.It was found that the corrosion rate of SFCAMCs increases as the temperature rising,and the bigger pore size of SiC foam ceramic reinforcement,the better corrosion resistance of SFCAMCs.展开更多
基金the Department of Science & Technology (DST) for their financial support for carrying out this research through Fast Track Scheme (DST Sanction No: SR/FT/ET-005/2008)Technical Education Quality Improvement Programme (TEQIP)
文摘Ultra-high strength Al alloy system was developed by cryorolling and the contribution of various strengthening mechanisms to the overall yield strength of the system was evaluated. Cryorolling of Al-4%Cu-3%TiB2 in situ composite followed by short annealing at 175 ℃ and ageing at 125℃ resulted in an ultra-high yield strength of about 800 MPa with 9%total elongation. The strengthening contributions form solid solution strengthening, grain refinement, dislocation strengthening, precipitation hardening and dispersion strengthening were evaluated using standard equations. It was estimated that the maximum contribution was from grain refinement due to cryorolling followed by precipitation and dispersion strengthening.
基金supported by the Korea Atomic Energy Research Institute (KAERI) R&D Program
文摘The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.
基金Project(00008713)supported by the Program of the Science and Technology Creative Team of Universities in Jiangxi,ChinaProject(2013-KLP-04)supported by the Open Foundation of Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials,China
文摘SiC foam ceramic reinforced aluminum matrix composites(SFCAMCs)were prepared by squeeze casting aluminum alloy(Al-23Si)into the SiC foam ceramic with different pore sizes,and the corrosion behavior of the SFCAMCs was studied in NaCl solutions.Static immersion corrosion tests were conducted at 20°C,50°C and 80°C,respectively.Corrosion morphology and products were analyzed by scanning electron microscope,energy dispersive system and X-ray diffraction.It was found that the corrosion rate of SFCAMCs increases as the temperature rising,and the bigger pore size of SiC foam ceramic reinforcement,the better corrosion resistance of SFCAMCs.
