This review is concerned with the effect of the addition of zirconium as a third element on the heat-resisting properties of Fe_3Al intermetallic compounds and explains their high-temperature oxidation mechanism.The F...This review is concerned with the effect of the addition of zirconium as a third element on the heat-resisting properties of Fe_3Al intermetallic compounds and explains their high-temperature oxidation mechanism.The Fe_3Al and Fe_3Al-0.05Zr specimens were isothermally oxidized in the temperature range of 1173～1473 K in synthetic air for 100 h.The formation of the alumina layer approximately obeyed the parabolic rate law,with the exception of short initial stage.The parabolic rate constant values for the Zr-doped Fe_3Al decreased at all tested temperatures.Fe_3Al revealed massive spallation,whereas Fe_3AlZr produced a flat,adherent oxide layer.The microstructure investigations of the alumina scales grown thermally on the Fe_3Al-Zr alloy by means of SEM-EDS showed that they were 1.5～2μm thick and consisted of a small inner columnar layer and an equiaxed outer grain layer.Additionally,very fine(50～150 nm) oxide particles rich in Zr were found across the alumina scales.The addition of Zr significantly affected the oxidation behavior of Fe_3Al by improving the adherence of theα-Al_2O_3 scale.TEM-SAD investigations of the alumina scales on samples prepared using the FIB(Focused Ion Beam) method confirmed the presence of small tetragonal zirconia grains near the scale/gas and alloy/scale interfaces,most of which were formed along alumina grain boundaries(gbs).Zr gb-segregation was found using HRTEM.The role of preferential formation of zirconium oxide along the alumina scale grain boundaries and the effect of Zr gb-segregation on oxidation and scale growth mechanisms were analyzed by means of two-stage oxidation experiments using ^(16)O_2/^(18)O_2.The SIMS oxygen isotope profiles for the Fe_3Al-Zr alloy oxidized at 1373 K, after two-stage oxidation experiments,revealed that oxygen anion diffusion is predominant compared to that of aluminum cation diffusion.展开更多
This study investigated the morphology, structure and tribological properties of the three samples produced by anodic oxidation of Ti10 V2 Fe3 Al in a sulfuric/phosphoric acid electrolyte(SPA), a near-neutral sodium t...This study investigated the morphology, structure and tribological properties of the three samples produced by anodic oxidation of Ti10 V2 Fe3 Al in a sulfuric/phosphoric acid electrolyte(SPA), a near-neutral sodium tartrate electrolyte without nanoparticles(STA) and a nearneutral sodium tartrate electrolyte with polytetrafluoroethylene(PTFE) nanoparticles(CA) in suspension. The STA film had a surface full of bulges and cracks, the SPA film was porous, and the CA film was nanoporous. The SPA film was mainly composed of anatase TiO2, whereas the STA and CA films were mainly amorphous TiO2 with little anatase. The tribological tests indicated that the SPA sample had a lower wear resistance than the titanium alloy substrate, which was attributed to the shedding of abrasive debris, leading to rapid wear. Both STA and CA samples exhibited much lower wear rates than the titanium alloy substrate, and CA sample displayed the lowest wear rate attributed to the formation of a lubricating layer by PTFE nanoparticles. The wear mechanisms are proposed.展开更多
文摘This review is concerned with the effect of the addition of zirconium as a third element on the heat-resisting properties of Fe_3Al intermetallic compounds and explains their high-temperature oxidation mechanism.The Fe_3Al and Fe_3Al-0.05Zr specimens were isothermally oxidized in the temperature range of 1173～1473 K in synthetic air for 100 h.The formation of the alumina layer approximately obeyed the parabolic rate law,with the exception of short initial stage.The parabolic rate constant values for the Zr-doped Fe_3Al decreased at all tested temperatures.Fe_3Al revealed massive spallation,whereas Fe_3AlZr produced a flat,adherent oxide layer.The microstructure investigations of the alumina scales grown thermally on the Fe_3Al-Zr alloy by means of SEM-EDS showed that they were 1.5～2μm thick and consisted of a small inner columnar layer and an equiaxed outer grain layer.Additionally,very fine(50～150 nm) oxide particles rich in Zr were found across the alumina scales.The addition of Zr significantly affected the oxidation behavior of Fe_3Al by improving the adherence of theα-Al_2O_3 scale.TEM-SAD investigations of the alumina scales on samples prepared using the FIB(Focused Ion Beam) method confirmed the presence of small tetragonal zirconia grains near the scale/gas and alloy/scale interfaces,most of which were formed along alumina grain boundaries(gbs).Zr gb-segregation was found using HRTEM.The role of preferential formation of zirconium oxide along the alumina scale grain boundaries and the effect of Zr gb-segregation on oxidation and scale growth mechanisms were analyzed by means of two-stage oxidation experiments using ^(16)O_2/^(18)O_2.The SIMS oxygen isotope profiles for the Fe_3Al-Zr alloy oxidized at 1373 K, after two-stage oxidation experiments,revealed that oxygen anion diffusion is predominant compared to that of aluminum cation diffusion.
基金financially supported by the Chongqing Research Program of Basic Research and Frontier Technology(No.cstc2016jcyjA0388)the National Natural Science Foundation of China(No.51701029),the Research and Development Project from COMAC and BOEING(No.2017-GT-088)+2 种基金China Postdoctoral Science Foundation Funded Project(Nos.2017M620410 and 2018T110942)the Chongqing Postdoctoral Scientific Research Foundation(No.Xm2017010)the Fundamental Research Funds for the Central Universities(No.2018CDGFCL005)。
文摘This study investigated the morphology, structure and tribological properties of the three samples produced by anodic oxidation of Ti10 V2 Fe3 Al in a sulfuric/phosphoric acid electrolyte(SPA), a near-neutral sodium tartrate electrolyte without nanoparticles(STA) and a nearneutral sodium tartrate electrolyte with polytetrafluoroethylene(PTFE) nanoparticles(CA) in suspension. The STA film had a surface full of bulges and cracks, the SPA film was porous, and the CA film was nanoporous. The SPA film was mainly composed of anatase TiO2, whereas the STA and CA films were mainly amorphous TiO2 with little anatase. The tribological tests indicated that the SPA sample had a lower wear resistance than the titanium alloy substrate, which was attributed to the shedding of abrasive debris, leading to rapid wear. Both STA and CA samples exhibited much lower wear rates than the titanium alloy substrate, and CA sample displayed the lowest wear rate attributed to the formation of a lubricating layer by PTFE nanoparticles. The wear mechanisms are proposed.
