The thermal stability of the rare earth rich phase particles in α, α+β and β phase regions of Ti 5Al 4Sn 2Zr 1Mo 0 25Si 1Nd(Ti 55) high temperature titanium alloy heat treated was studied. Under ...The thermal stability of the rare earth rich phase particles in α, α+β and β phase regions of Ti 5Al 4Sn 2Zr 1Mo 0 25Si 1Nd(Ti 55) high temperature titanium alloy heat treated was studied. Under conditions of 600～980 ℃/1～100 h and 1050～1500 ℃/1～10 h, the average particle size ranges from 3 34 to 4 20 μm, the circularity shape factor from 0 619 to 0 759, and the volume fraction from 1 4% to 1 8%. The results show that nearly no change is found for the size, shape, and volume fraction of the particles in the alloy, and the rare earth rich phase particles exhibit thermal stability.展开更多
Compared to North American shale composition (NASC), REE contents of sediments from the CC area in the Pacific Ocean are obviously high except that cerium has equal content to that of NASC. Three-valence rare earth el...Compared to North American shale composition (NASC), REE contents of sediments from the CC area in the Pacific Ocean are obviously high except that cerium has equal content to that of NASC. Three-valence rare earth elements were completely enriched in phosphate-phase and cerium in iron-phase. Rare earth elements in the sediments were originally derived from seawater. During lithi- genic and minerogenic processes of metalliferous nodules, three-valence rare earth elements in sediments mobilized and incorporated into sediments as authigenous biogenic-apatite, while cerium had change from Ce3+ to Ce4+ and directly precipitated from seawater and entered metalliferous nodules and caused Ce anomalies in REE pattern in sediments.展开更多
Microstructure evolution of rare earth rich phase of rapidly-solidified (RS) TiAl based alloys was investigated. The two rapid-solidification techniques employed are melt-spinning technique (MS) and Hammer-and-Anvil t...Microstructure evolution of rare earth rich phase of rapidly-solidified (RS) TiAl based alloys was investigated. The two rapid-solidification techniques employed are melt-spinning technique (MS) and Hammer-and-Anvil technique (HB). MS ribbons and HA foils were obtained in the experiment. The results demonstrate that with the increasing of cooling rates of TiAl based alloys great changes are taken place in the microstructures of rare earth rich phase, from scattering mainly on grain boundaries of as-cast ingot to distributing homogeneously as very fine fibers or powders (nanometer grade) on the matrix. The fine paralleling second phase fibers in the HA foils are considered to be connected with gamma/alpha (2) lamellar colonies. Selected area electronic diffraction (SAED) patterns of the rare earth rich phase is in accordance with that of intermetallic AlCe.展开更多
Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an...Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an effective modifying agent, which makes the coarse Fe rich impurity phases transform into complex compounds of tiny, sphere/short stick form, thus improving mechanical properties of this material; its modifying mechanism is in that RE gathering in front of solid/liquid interface enters into the impurity phases, forming complex (AlFeSiRE) compounds; or is adsorbed in the impurity phases surface, impeding the growth of impurity phases; however, excessive RE will result in the increasing of RE compounds (secondary phases), and plasticity reduction of this material. Therefore, its addition amount should be less than 0 07% (mass fraction).展开更多
Tb0.3Dy0.7HoxFe1.95（x=0.00, 0.05, 0.10, 0.15, 0.20, 0.35, 0.50, 0.65） quaternary alloys were prepared by arc-melting and followed by annealing.The phases present and structure of the alloys were determined using a D...Tb0.3Dy0.7HoxFe1.95（x=0.00, 0.05, 0.10, 0.15, 0.20, 0.35, 0.50, 0.65） quaternary alloys were prepared by arc-melting and followed by annealing.The phases present and structure of the alloys were determined using a D8-Advance X-ray diffractometer.The magnetostriction of the alloys was studied by standard strain gauge technique.The dependence of Ho content on the structure, magnetostriction and density of the alloys was investigated in detail.The research results showed that Ho-doping did not change MgCu2-type cubic Laves structure in Tb0.3Dy0.7Fe1.95.When Ho content x≤0.2, rich rare earth phase presented in the alloys increased and magnetostriction of the alloys reduced evidently with increasing x, but for alloys with x〉0.2, the content of rich rare earth phase started to reduce and the magnetostriction increased quickly, especially at low magnetic field in the alloy with x=0.65 due to separation of rich rare earth phases on the surface of the alloy.展开更多
文摘The thermal stability of the rare earth rich phase particles in α, α+β and β phase regions of Ti 5Al 4Sn 2Zr 1Mo 0 25Si 1Nd(Ti 55) high temperature titanium alloy heat treated was studied. Under conditions of 600～980 ℃/1～100 h and 1050～1500 ℃/1～10 h, the average particle size ranges from 3 34 to 4 20 μm, the circularity shape factor from 0 619 to 0 759, and the volume fraction from 1 4% to 1 8%. The results show that nearly no change is found for the size, shape, and volume fraction of the particles in the alloy, and the rare earth rich phase particles exhibit thermal stability.
基金the R&D Project on the Oceanic Metalliferous Nodue during the "Ninth- Five- YearPlan"(No. DY95 ~ 02 ~ 10).
文摘Compared to North American shale composition (NASC), REE contents of sediments from the CC area in the Pacific Ocean are obviously high except that cerium has equal content to that of NASC. Three-valence rare earth elements were completely enriched in phosphate-phase and cerium in iron-phase. Rare earth elements in the sediments were originally derived from seawater. During lithi- genic and minerogenic processes of metalliferous nodules, three-valence rare earth elements in sediments mobilized and incorporated into sediments as authigenous biogenic-apatite, while cerium had change from Ce3+ to Ce4+ and directly precipitated from seawater and entered metalliferous nodules and caused Ce anomalies in REE pattern in sediments.
文摘Microstructure evolution of rare earth rich phase of rapidly-solidified (RS) TiAl based alloys was investigated. The two rapid-solidification techniques employed are melt-spinning technique (MS) and Hammer-and-Anvil technique (HB). MS ribbons and HA foils were obtained in the experiment. The results demonstrate that with the increasing of cooling rates of TiAl based alloys great changes are taken place in the microstructures of rare earth rich phase, from scattering mainly on grain boundaries of as-cast ingot to distributing homogeneously as very fine fibers or powders (nanometer grade) on the matrix. The fine paralleling second phase fibers in the HA foils are considered to be connected with gamma/alpha (2) lamellar colonies. Selected area electronic diffraction (SAED) patterns of the rare earth rich phase is in accordance with that of intermetallic AlCe.
文摘Modifying effect and mechanism of trace rare earth on Fe(Si) rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce rich mixed rare earth (RE) is an effective modifying agent, which makes the coarse Fe rich impurity phases transform into complex compounds of tiny, sphere/short stick form, thus improving mechanical properties of this material; its modifying mechanism is in that RE gathering in front of solid/liquid interface enters into the impurity phases, forming complex (AlFeSiRE) compounds; or is adsorbed in the impurity phases surface, impeding the growth of impurity phases; however, excessive RE will result in the increasing of RE compounds (secondary phases), and plasticity reduction of this material. Therefore, its addition amount should be less than 0 07% (mass fraction).
基金supported by the National Natural Science Foundation of China(50661002)Guangxi Provincial Natural Science Foundation of China (0575095)
文摘Tb0.3Dy0.7HoxFe1.95（x=0.00, 0.05, 0.10, 0.15, 0.20, 0.35, 0.50, 0.65） quaternary alloys were prepared by arc-melting and followed by annealing.The phases present and structure of the alloys were determined using a D8-Advance X-ray diffractometer.The magnetostriction of the alloys was studied by standard strain gauge technique.The dependence of Ho content on the structure, magnetostriction and density of the alloys was investigated in detail.The research results showed that Ho-doping did not change MgCu2-type cubic Laves structure in Tb0.3Dy0.7Fe1.95.When Ho content x≤0.2, rich rare earth phase presented in the alloys increased and magnetostriction of the alloys reduced evidently with increasing x, but for alloys with x〉0.2, the content of rich rare earth phase started to reduce and the magnetostriction increased quickly, especially at low magnetic field in the alloy with x=0.65 due to separation of rich rare earth phases on the surface of the alloy.
