Foil powders of Al 5.0 Cr 4.0 Y 1.5 Zr (%) were prepared by using a multi stage atomization rapid solidification powder making device. The obtained powders were exposed thermally at various temperatures. Variation of ...Foil powders of Al 5.0 Cr 4.0 Y 1.5 Zr (%) were prepared by using a multi stage atomization rapid solidification powder making device. The obtained powders were exposed thermally at various temperatures. Variation of microstructures and properties of the alloy powders was investigated by micro hardness measurement, X ray diffraction, differential thermal analysis, and transmission electron microscopy with energy disperse X ray analyses. The results show that cubic Al 20 Cr 2Y ( a = 1.437?nm) and metastable Ll 2 Al 3Zr (FCC, a = 0.405?1?nm) or equilibrium DO 23 Al 3Zr (tetragonal structure, a = 0.409?1?nm, b = 1.73?0?nm) are main second phases precipitated from supersaturated solid solution of the rapidly solidified foil powders during thermal exposure. The cubic dispersion precipitates prior to the two other Al 3Zr type intermetallic phases in the course of the decomposition. Precipitation of incoherent Al 20 Cr 2Y results in softening of foil powder, and coherent Ll 2 Al 3Zr has intensive precipitation strengthening effect. The Al 20 Cr 2Y phase is structurally stable, but it is prone to coarsen and polygonize above 450?℃. Both Al 3Zr type intermetallic phases have much smaller coarsening rate than Al 20 Cr 2Y at temperature higher than 450?℃. These two phases are able to keep their fine spherical morphologies up to 550?℃, but Al 3Zr transforms into DO 23 structure from Ll 2 structure during thermal exposure above 550?℃.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
文摘Foil powders of Al 5.0 Cr 4.0 Y 1.5 Zr (%) were prepared by using a multi stage atomization rapid solidification powder making device. The obtained powders were exposed thermally at various temperatures. Variation of microstructures and properties of the alloy powders was investigated by micro hardness measurement, X ray diffraction, differential thermal analysis, and transmission electron microscopy with energy disperse X ray analyses. The results show that cubic Al 20 Cr 2Y ( a = 1.437?nm) and metastable Ll 2 Al 3Zr (FCC, a = 0.405?1?nm) or equilibrium DO 23 Al 3Zr (tetragonal structure, a = 0.409?1?nm, b = 1.73?0?nm) are main second phases precipitated from supersaturated solid solution of the rapidly solidified foil powders during thermal exposure. The cubic dispersion precipitates prior to the two other Al 3Zr type intermetallic phases in the course of the decomposition. Precipitation of incoherent Al 20 Cr 2Y results in softening of foil powder, and coherent Ll 2 Al 3Zr has intensive precipitation strengthening effect. The Al 20 Cr 2Y phase is structurally stable, but it is prone to coarsen and polygonize above 450?℃. Both Al 3Zr type intermetallic phases have much smaller coarsening rate than Al 20 Cr 2Y at temperature higher than 450?℃. These two phases are able to keep their fine spherical morphologies up to 550?℃, but Al 3Zr transforms into DO 23 structure from Ll 2 structure during thermal exposure above 550?℃.
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.
