The microstructures and mechanical properties of an iron-based alloy (Fe-13Cr-3W-0.4Ti-0.25Y-0.30O) prepared by mechanical alloying were investigated with scanning electron microscope,optical microscope,X-ray diffract...The microstructures and mechanical properties of an iron-based alloy (Fe-13Cr-3W-0.4Ti-0.25Y-0.30O) prepared by mechanical alloying were investigated with scanning electron microscope,optical microscope,X-ray diffractometer and hardness tester.The results show that the particle size does not decrease with milling time because serious welding occurs at 144 h.The density of the alloy sintered at 1 523 K is affected by the particle size of the powder.Finer particles lead to a high sintered density,while the bulk density by using particles milled for 144 h is as low as 70%.In the microstructures of the annealed alloy,large elongated particles and fine equiaxed grains can be detected.The elongated particle zone has a higher microhardness than the equiaxed grain area in the annealed alloys due to the larger residual strain and higher density of the precipitated phase.展开更多
A Ni-Cr-B-Si coating technique was developed and successfully applied on austenite grey iron substrate in a conventional resistance furnace under graphite powder protection. The microstructure, phase distribution, che...A Ni-Cr-B-Si coating technique was developed and successfully applied on austenite grey iron substrate in a conventional resistance furnace under graphite powder protection. The microstructure, phase distribution, chemical composition profile and microhardness along the coating layer depth were investigated. Shear strength of the coating was also tested. Microanalysis shows that the coating is consist of γ-Ni solution and γ-Ni+Ni3B lamellar eutectic, as well as small amount of Cr5B3 particles. Diffusion induced metallurgical bonding occurs at the coating/substrate interfaces, and the higher the temperature, the more sufficient elements diffused, the broader interfusion region and the larger bonding strength, but it has an optimum value. And the bonding strength at the interface can be enable to reach 250-270 MPa, which is nearly the same as that of processed by flame spray. The microhardness along the coating layer depth shows a gradient distribution manner.展开更多
基金Project(50634060) supported by the National Natural Science Foundation of China Project(50721003) supported by the Creative Research Group of National Natural Science Foundation of China
文摘The microstructures and mechanical properties of an iron-based alloy (Fe-13Cr-3W-0.4Ti-0.25Y-0.30O) prepared by mechanical alloying were investigated with scanning electron microscope,optical microscope,X-ray diffractometer and hardness tester.The results show that the particle size does not decrease with milling time because serious welding occurs at 144 h.The density of the alloy sintered at 1 523 K is affected by the particle size of the powder.Finer particles lead to a high sintered density,while the bulk density by using particles milled for 144 h is as low as 70%.In the microstructures of the annealed alloy,large elongated particles and fine equiaxed grains can be detected.The elongated particle zone has a higher microhardness than the equiaxed grain area in the annealed alloys due to the larger residual strain and higher density of the precipitated phase.
基金The paper is supported by country-level Spark Plan in 2003,project No.: 2003EA690034.
文摘A Ni-Cr-B-Si coating technique was developed and successfully applied on austenite grey iron substrate in a conventional resistance furnace under graphite powder protection. The microstructure, phase distribution, chemical composition profile and microhardness along the coating layer depth were investigated. Shear strength of the coating was also tested. Microanalysis shows that the coating is consist of γ-Ni solution and γ-Ni+Ni3B lamellar eutectic, as well as small amount of Cr5B3 particles. Diffusion induced metallurgical bonding occurs at the coating/substrate interfaces, and the higher the temperature, the more sufficient elements diffused, the broader interfusion region and the larger bonding strength, but it has an optimum value. And the bonding strength at the interface can be enable to reach 250-270 MPa, which is nearly the same as that of processed by flame spray. The microhardness along the coating layer depth shows a gradient distribution manner.
