The relationship between the microstructure transformation of type 17-4 PH stainless steel and the aging hardening behavior was investigated. The results showed that, when 17-4 PH stainless steel aging at 595℃, the b...The relationship between the microstructure transformation of type 17-4 PH stainless steel and the aging hardening behavior was investigated. The results showed that, when 17-4 PH stainless steel aging at 595℃, the bulk hardness of samples attains its peak value （42.5 HRC） for about 20 min, and then decreases at all time. TEM revealed the microstructure corresponding with peak hardness is that the fine spheroid-shape copper with the fcc crystal structure and the fiber-shape secondary carbide M23C6 precipitated from the lath martensite matrix. Both precipitations of copper and M23C6 are the reasons for strengthening of the alloy at this temperature. With the extension of holding time at this temperature, the copper and secondary carbide grow and lose the coherent relationship with the matrix, so the bulk hardness of samples decreases.展开更多
V-4Cr-4Ti is the leading candidate vanadium alloy for fusion applications as structural material of first wall and blanket. Due to the interaction between Ti and interstitial solutes of C, N, and O, precipitation occu...V-4Cr-4Ti is the leading candidate vanadium alloy for fusion applications as structural material of first wall and blanket. Due to the interaction between Ti and interstitial solutes of C, N, and O, precipitation occurs at elevated temperature. The behavior has been studied in the past few years by short time annealing and results showed that it may greatly affect its mechanical properties Ti-CON type precipitates, appearing at- 700℃ in the solid-solution annealed alloy in high number density and small size, strengthen the alloy significantly and reduce its ductility. As the ductility reduction is in an acceptable level, the strengthening might be utilized for a light and strong vanadium alloy structure. Before a conclusion, uncertainty of its thermal stability should be studied during the high temperature serves. Besides, seldom has been studied for the effect of long time aging on precipitation behavior and tensile properties of the alloy.展开更多
The tribological properties especially wear and hardness of a Ti-Al-V alloy with nitrogen implantation (energy 60 keV) were investigated. The implantation was carried out at fluences range from 1×1016 to 4×1...The tribological properties especially wear and hardness of a Ti-Al-V alloy with nitrogen implantation (energy 60 keV) were investigated. The implantation was carried out at fluences range from 1×1016 to 4×1017 ions/cm2. Glancing angle X-ray diffraction (GAXRD) and X-ray photoelectron spectroscopy (XPS) analyses were performed to obtain surface characterization of the implanted sample. The unimplanted and implanted samples were also annealed at 600 ℃ in order to understand the influence of annealing on the tribological properties of Ti-Al-V. The hardness shows significant improvement at the higher fluence. After annealing at 600 ℃, the friction coefficient exhibits a relative decrease for the nitrogen-implanted samples. In addition, the wear rates of the implanted samples exhibits a great decrease after annealing at 600 ℃. Nature of the surface and reason for the variation and improvement in wear resistance were discussed in detail.展开更多
Microstructure evolution of AZ31 Mg alloy during change-channel angular extrusion （CCAE） was investigated. The grains of AZ31 Mg alloy were refined significantly from 500 mm to 15 mm after CCAE deformed at 523 K. Di...Microstructure evolution of AZ31 Mg alloy during change-channel angular extrusion （CCAE） was investigated. The grains of AZ31 Mg alloy were refined significantly from 500 mm to 15 mm after CCAE deformed at 523 K. Dislocations were induced at the initial stage of extrusion and they rearranged themselves to form dislocation boundaries and sub-grain boundaries during deformation. When the specimen through the horizontal change channel with the strain increased, the sub-boundaries evolved to high angle grain boundaries （HAGB）. The process of grain refinement can be described as continuous dynamic recovery and recrystallization （CDRR）.展开更多
Titanium carbide coatings are widely used as various wear-resistant material. The hydrogen erosion resistance of TiC-C films and the effect of hydrogen participation on TiC-C films were studied. Seventy-five percent T...Titanium carbide coatings are widely used as various wear-resistant material. The hydrogen erosion resistance of TiC-C films and the effect of hydrogen participation on TiC-C films were studied. Seventy-five percent TiC-C films are prepared on stainless steel surface by using ion mixing, where TiC-C films are deposited by rf magnetron sputtering followed by argon ion bombardment. The samples are then submitted to hydrogen ion implantation at 1.2 × 10^-3 Pa. Characterization for the 75% TiC-C films was done with SIMS, XRD, AES, and XPS. Secondary ion mass spectroscopy （SIMS） was used to analyze hydrogen concentration variation with depth, X-Ray diffraction （XRD） was used to identify the phases, and Auger electron spectra （AES） as well as X-ray photoelectron spectra （XPS） were used to check the effects of hydrogen on shifts of chemical bonding states of C and Ti in the TiC-C films. It is found that TiC-C films on stainless steel surface can prevent hydrogen from entering stainless steel.展开更多
基金This work was financially supported by the Key Nuclear Fuel and Nuclear Materials Laboratory of China(No.51481080104ZS8501).
文摘The relationship between the microstructure transformation of type 17-4 PH stainless steel and the aging hardening behavior was investigated. The results showed that, when 17-4 PH stainless steel aging at 595℃, the bulk hardness of samples attains its peak value （42.5 HRC） for about 20 min, and then decreases at all time. TEM revealed the microstructure corresponding with peak hardness is that the fine spheroid-shape copper with the fcc crystal structure and the fiber-shape secondary carbide M23C6 precipitated from the lath martensite matrix. Both precipitations of copper and M23C6 are the reasons for strengthening of the alloy at this temperature. With the extension of holding time at this temperature, the copper and secondary carbide grow and lose the coherent relationship with the matrix, so the bulk hardness of samples decreases.
文摘V-4Cr-4Ti is the leading candidate vanadium alloy for fusion applications as structural material of first wall and blanket. Due to the interaction between Ti and interstitial solutes of C, N, and O, precipitation occurs at elevated temperature. The behavior has been studied in the past few years by short time annealing and results showed that it may greatly affect its mechanical properties Ti-CON type precipitates, appearing at- 700℃ in the solid-solution annealed alloy in high number density and small size, strengthen the alloy significantly and reduce its ductility. As the ductility reduction is in an acceptable level, the strengthening might be utilized for a light and strong vanadium alloy structure. Before a conclusion, uncertainty of its thermal stability should be studied during the high temperature serves. Besides, seldom has been studied for the effect of long time aging on precipitation behavior and tensile properties of the alloy.
文摘The tribological properties especially wear and hardness of a Ti-Al-V alloy with nitrogen implantation (energy 60 keV) were investigated. The implantation was carried out at fluences range from 1×1016 to 4×1017 ions/cm2. Glancing angle X-ray diffraction (GAXRD) and X-ray photoelectron spectroscopy (XPS) analyses were performed to obtain surface characterization of the implanted sample. The unimplanted and implanted samples were also annealed at 600 ℃ in order to understand the influence of annealing on the tribological properties of Ti-Al-V. The hardness shows significant improvement at the higher fluence. After annealing at 600 ℃, the friction coefficient exhibits a relative decrease for the nitrogen-implanted samples. In addition, the wear rates of the implanted samples exhibits a great decrease after annealing at 600 ℃. Nature of the surface and reason for the variation and improvement in wear resistance were discussed in detail.
基金Funded by the "Major State Basic Research Development Program of China(973 Program) (2007CB613700)
文摘Microstructure evolution of AZ31 Mg alloy during change-channel angular extrusion （CCAE） was investigated. The grains of AZ31 Mg alloy were refined significantly from 500 mm to 15 mm after CCAE deformed at 523 K. Dislocations were induced at the initial stage of extrusion and they rearranged themselves to form dislocation boundaries and sub-grain boundaries during deformation. When the specimen through the horizontal change channel with the strain increased, the sub-boundaries evolved to high angle grain boundaries （HAGB）. The process of grain refinement can be described as continuous dynamic recovery and recrystallization （CDRR）.
基金Item Sponsored by National Natural Science Foundation of China (98061001)Foundation of the Institute of Engineering Physics of China(9603025)
文摘Titanium carbide coatings are widely used as various wear-resistant material. The hydrogen erosion resistance of TiC-C films and the effect of hydrogen participation on TiC-C films were studied. Seventy-five percent TiC-C films are prepared on stainless steel surface by using ion mixing, where TiC-C films are deposited by rf magnetron sputtering followed by argon ion bombardment. The samples are then submitted to hydrogen ion implantation at 1.2 × 10^-3 Pa. Characterization for the 75% TiC-C films was done with SIMS, XRD, AES, and XPS. Secondary ion mass spectroscopy （SIMS） was used to analyze hydrogen concentration variation with depth, X-Ray diffraction （XRD） was used to identify the phases, and Auger electron spectra （AES） as well as X-ray photoelectron spectra （XPS） were used to check the effects of hydrogen on shifts of chemical bonding states of C and Ti in the TiC-C films. It is found that TiC-C films on stainless steel surface can prevent hydrogen from entering stainless steel.
