Transmission electron microscopy (TEM) is a very powerful technique for materials characteriza-tion, providing information relating to morphology, composition, and crystal structure. Selected area diffraction patterns...Transmission electron microscopy (TEM) is a very powerful technique for materials characteriza-tion, providing information relating to morphology, composition, and crystal structure. Selected area diffraction patterns (SADPs) are crystallographic data that can be obtained using a TEM in-strument. Conventional identification through SADP/TEM is tricky and tedious, thereby increasing the difficulty of phase identification. To establish a procedure for phase identification of known and unknown phases, in this study we examined two samples: one, a known phase, was Si with alignment;the other, unknown, was the TixOy phase at the 96.4Au-3Ni-0.6Ti interlayer/ yttria-stabilized zirconia (YSZ) interface of a steel/96.4Au-3Ni-0.6Ti interlayer/YSZ joint. The procedures for phase identification of the known and unknown phases are described herein using a series of SADPs and energy dispersive spectrometry within TEM that would be useful for general researchers.展开更多
Medium-entropy alloys(MEAs)have garnered significant interest due to their unique mechanical prop-erties,but phase instabilities such as the formation of brittle sigma(σ)phase during annealing pose challenges to thei...Medium-entropy alloys(MEAs)have garnered significant interest due to their unique mechanical prop-erties,but phase instabilities such as the formation of brittle sigma(σ)phase during annealing pose challenges to their practical application.This study investigates the microstructural evolution and me-chanical behavior of an 80%cold-rolled Fe_(45)Co_(35)Cr_(10)V_(10)MEA that was isochronally annealed between 100℃ and 900℃ for 300 s and characterized using hardness indentations,in-situ X-ray diffraction,and thermodynamic calculations,with high-resolution electron microscopy detailing microstructural evo-lution at 625℃,675℃,and 725℃.The results show increases in Vickers hardness between 500℃ and 625℃,attributed to the nucleation of a Cr-and V-rich sigma(σ)phase,primarily at the bcc grain boundaries.Beyond 625℃,the hardness decreased due toσ-phase dissolution,recovery of bcc and fcc phases,bcc→fcc phase reversion,and recrystallization of the reverted fcc phase.Scanning-transmission electron microscopy and transmission Kikuchi diffraction revealed a Kurdjumov-Sachs orientation rela-tionship(OR)at 675℃ and a near Nishiyama-Wassermann OR at 725℃ for bcc-fcc interfaces,whereas bcc-σand fcc-σinterfaces showed no dominant OR.In addition toσphase,two types of bcc phase were identified at 625℃.Type 1 bcc initially retained a near-nominal composition and a disordered crystal structure from deformation-induced bcc martensite but gradually became Fe-enriched and Cr-and V-depleted up to 725℃.In contrast,Type 2 bcc phase was Fe-depleted and Co-enriched at 625℃ but dis-appeared at 675℃,coinciding with the onset of bcc→fcc phase reversion.This phase also exhibited B2-like chemical short-range ordering,with alternating FeCo-rich and CrV-rich domains.This study provides insights into the complex phase transformation occurring between 500℃ and 725℃ in a Fe_(45)Co_(35)Cr_(10)V_(10)MEA,which can be leveraged to design alloys with optimized mechanical properties for practical appli-cations.展开更多
Phase equilibria in the Fe-Nb-Zr system at 1,200 ℃ were determined by X-ray diffraction （XRD） and scanning electron microscope （SEM） coupled with energydispersive X-ray spectroscopy （EDS） techniques. Extensive ...Phase equilibria in the Fe-Nb-Zr system at 1,200 ℃ were determined by X-ray diffraction （XRD） and scanning electron microscope （SEM） coupled with energydispersive X-ray spectroscopy （EDS） techniques. Extensive NbFez domain was proposed in the current work. This compound existed in the composition range from 35 at% to 73 at% Fe, 12 at% to 32 at% Nb, and 0 to 32 at% Zr. In the present work, four three-phase regions （1）-（Nb,Zr） ＋ NbFe ＋ NbFe2, （2） [3-（Nb,Zr） ＋ NbFe2 ＋ Liquid, （3） NbFe2 ＋ Liquid ＋ ZrFe2, and （4） ZrFe2 ＋ Fe ＋ NbFe2, were established.展开更多
Microstructure and phase transformation in the Al-Cu-Fe alloys of the approximate compositional range of 20 - 50 at.% Cu and 2 - 10 Fe at.% have been investigated from samples quenched from their respective temperatur...Microstructure and phase transformation in the Al-Cu-Fe alloys of the approximate compositional range of 20 - 50 at.% Cu and 2 - 10 Fe at.% have been investigated from samples quenched from their respective temperatures by means of different thermal analysis, magnetothermal analysis, scanning electron microscopy, electron probe analysis and powder X-ray diffraction. Representative phase transformations categorized as polymorphic, discontinuous precipitation, quasi-binary eutectoid, and ternary transitional U-type phase transformation are presented. These phase transformations were found to have a common feature which consumes the phase and appears the phase. A schematic diagram was proposed to demonstrate the transition processes with decreasing temperature.展开更多
The phase relationship in the Er-Si-Ti ternary system at 773 K was investigated mainly by X-ray powder diffraction analysis with the aid of scanning electron microscope analysis in this work.The existence of nine bina...The phase relationship in the Er-Si-Ti ternary system at 773 K was investigated mainly by X-ray powder diffraction analysis with the aid of scanning electron microscope analysis in this work.The existence of nine binary compounds ErsSi3,Er5Si4,ErSi,EraSi5,Si2Ti,SiTi,Si4Tis,Si3Tis,SiTi3 and two ternary compounds ErSiTi and Er2SigTi3 was confirmed in this system at 773 K.The homogeneity range of Er3Si5 phase extended from about 63 at%Si to 66 at%Si in Er-Si system at 773 K.The homogeneity range of Si3Ti5 phase extended from about 62 at%Ti to 64 at%Ti in Si-Ti system at 773 K.The maximum solid solubility of Er in Si3Ti5 phase was found to be about 2 at%Er in Er-Si-Ti ternary system at 773K.At 773K,the isothermal section of phase diagram of the Er-Si-Ti ternary system was found to consist of fourteen single-phase regions,twenty-seven two-phase regions and fourteen three-phase regions.展开更多
文摘Transmission electron microscopy (TEM) is a very powerful technique for materials characteriza-tion, providing information relating to morphology, composition, and crystal structure. Selected area diffraction patterns (SADPs) are crystallographic data that can be obtained using a TEM in-strument. Conventional identification through SADP/TEM is tricky and tedious, thereby increasing the difficulty of phase identification. To establish a procedure for phase identification of known and unknown phases, in this study we examined two samples: one, a known phase, was Si with alignment;the other, unknown, was the TixOy phase at the 96.4Au-3Ni-0.6Ti interlayer/ yttria-stabilized zirconia (YSZ) interface of a steel/96.4Au-3Ni-0.6Ti interlayer/YSZ joint. The procedures for phase identification of the known and unknown phases are described herein using a series of SADPs and energy dispersive spectrometry within TEM that would be useful for general researchers.
基金provided by the Nano and Material Technology Development Program(RS-2023-00281246)via the National Research Foundation of Korea,Ministry of Science and ICT,KoreaThe JEOL JSM-7001F,JEOL ARM 200F,and FEI Helios G3 CX FIB-SEM were funded by the Australian Research Council-Linkage,Infrastructure,Equipment and Facilities GrantsNos.LE0882613,LE120100104 andLE160100063,respectivelyThe Oxford Instruments 80 mm2 X-Max EDS detector and the JEOL JEM F200 were funded via the 2012 UOW Major Equipment Grant and 2019 UOW Equipment Replacement Grant schemes,respectively.
文摘Medium-entropy alloys(MEAs)have garnered significant interest due to their unique mechanical prop-erties,but phase instabilities such as the formation of brittle sigma(σ)phase during annealing pose challenges to their practical application.This study investigates the microstructural evolution and me-chanical behavior of an 80%cold-rolled Fe_(45)Co_(35)Cr_(10)V_(10)MEA that was isochronally annealed between 100℃ and 900℃ for 300 s and characterized using hardness indentations,in-situ X-ray diffraction,and thermodynamic calculations,with high-resolution electron microscopy detailing microstructural evo-lution at 625℃,675℃,and 725℃.The results show increases in Vickers hardness between 500℃ and 625℃,attributed to the nucleation of a Cr-and V-rich sigma(σ)phase,primarily at the bcc grain boundaries.Beyond 625℃,the hardness decreased due toσ-phase dissolution,recovery of bcc and fcc phases,bcc→fcc phase reversion,and recrystallization of the reverted fcc phase.Scanning-transmission electron microscopy and transmission Kikuchi diffraction revealed a Kurdjumov-Sachs orientation rela-tionship(OR)at 675℃ and a near Nishiyama-Wassermann OR at 725℃ for bcc-fcc interfaces,whereas bcc-σand fcc-σinterfaces showed no dominant OR.In addition toσphase,two types of bcc phase were identified at 625℃.Type 1 bcc initially retained a near-nominal composition and a disordered crystal structure from deformation-induced bcc martensite but gradually became Fe-enriched and Cr-and V-depleted up to 725℃.In contrast,Type 2 bcc phase was Fe-depleted and Co-enriched at 625℃ but dis-appeared at 675℃,coinciding with the onset of bcc→fcc phase reversion.This phase also exhibited B2-like chemical short-range ordering,with alternating FeCo-rich and CrV-rich domains.This study provides insights into the complex phase transformation occurring between 500℃ and 725℃ in a Fe_(45)Co_(35)Cr_(10)V_(10)MEA,which can be leveraged to design alloys with optimized mechanical properties for practical appli-cations.
基金supported by the National Natural Science Foundation of China(No.51001033)the Natural Science Foundation of Guangxi(No.2011GXNSFA018030)+2 种基金the Program for Excellent Talents in Guangxi Higher Education InstitutionsScience Research Program for Education Department of Guangxi(No.2011LX140)the Science Foundation of Guangxi University for Nationalities(Nos.2008ZD010,2010ZD012,2011QD019,and 2011MDQN046)
文摘Phase equilibria in the Fe-Nb-Zr system at 1,200 ℃ were determined by X-ray diffraction （XRD） and scanning electron microscope （SEM） coupled with energydispersive X-ray spectroscopy （EDS） techniques. Extensive NbFez domain was proposed in the current work. This compound existed in the composition range from 35 at% to 73 at% Fe, 12 at% to 32 at% Nb, and 0 to 32 at% Zr. In the present work, four three-phase regions （1）-（Nb,Zr） ＋ NbFe ＋ NbFe2, （2） [3-（Nb,Zr） ＋ NbFe2 ＋ Liquid, （3） NbFe2 ＋ Liquid ＋ ZrFe2, and （4） ZrFe2 ＋ Fe ＋ NbFe2, were established.
文摘Microstructure and phase transformation in the Al-Cu-Fe alloys of the approximate compositional range of 20 - 50 at.% Cu and 2 - 10 Fe at.% have been investigated from samples quenched from their respective temperatures by means of different thermal analysis, magnetothermal analysis, scanning electron microscopy, electron probe analysis and powder X-ray diffraction. Representative phase transformations categorized as polymorphic, discontinuous precipitation, quasi-binary eutectoid, and ternary transitional U-type phase transformation are presented. These phase transformations were found to have a common feature which consumes the phase and appears the phase. A schematic diagram was proposed to demonstrate the transition processes with decreasing temperature.
文摘The phase relationship in the Er-Si-Ti ternary system at 773 K was investigated mainly by X-ray powder diffraction analysis with the aid of scanning electron microscope analysis in this work.The existence of nine binary compounds ErsSi3,Er5Si4,ErSi,EraSi5,Si2Ti,SiTi,Si4Tis,Si3Tis,SiTi3 and two ternary compounds ErSiTi and Er2SigTi3 was confirmed in this system at 773 K.The homogeneity range of Er3Si5 phase extended from about 63 at%Si to 66 at%Si in Er-Si system at 773 K.The homogeneity range of Si3Ti5 phase extended from about 62 at%Ti to 64 at%Ti in Si-Ti system at 773 K.The maximum solid solubility of Er in Si3Ti5 phase was found to be about 2 at%Er in Er-Si-Ti ternary system at 773K.At 773K,the isothermal section of phase diagram of the Er-Si-Ti ternary system was found to consist of fourteen single-phase regions,twenty-seven two-phase regions and fourteen three-phase regions.
