Showing papers on "Laves phase published in 2003"
TL;DR: In this paper, the growth and coarsening of the Laves phase was investigated for several advanced 9-12% Cr heat-resistant steels at 600 and 650 °C.
143 citations
TL;DR: In this article, the effect of different alloying elements on the order-disorder transition temperatures of quaternary alloys is discussed and compared with that of respective ternary Fe 3 Al-X alloys without Ti.
103 citations
TL;DR: In this paper, a diffusion-multiple approach was employed to determine the phase diagram of the Nb-Cr-Si ternary system, which is critical for the design of niobium silicide-based in situ composites.
102 citations
TL;DR: Structural changes in the quasi-binary system CaAl(2)(-)(x)Mg(x) are induced by the electron concentration, which decreases with increasing x, and the experimental compositional stability ranges of the three different Laves phase structures were reproduced very well.
Abstract: Compounds CaAl(2)(-)(x)Mg(x) (0 MgNi(2) --> MgZn(2) is revealed. The homogeneity ranges of the underlying phases were determined to be 0 < or = x < 0.24(1) (MgCu(2) type), 0.66(2) < x < 1.07(3) (MgNi(2) type), and 1.51(5) < x < or = 2.0 (MgZn(2) type). Mg/Al site occupancies in CaAl(1.34)Mg(0.66) and in CaAl(0.44)Mg(1.56) were refined from neutron powder diffraction experiments and exposed a pronounced segregation of Al and Mg in MgNi(2)-type CaAl(1.34)Mg(0.66) where Al atoms preferentially occupy the positions corresponding to trigonal bipyramids. In MgZn(2)-type CaAl(0.44)Mg(1.56), however, the Mg/Al distribution was found to be nearly uniform. Structural stability in the quasi-binary system CaAl(2)(-)(x)Mg(x) was investigated by first-principles calculations in which random occupational disorder of Mg and Al was modeled with the virtual crystal approximation. The theoretical calculations reproduced the experimental compositional stability ranges of the three different Laves phase structures very well. Structural changes in the quasi-binary system CaAl(2)(-)(x)Mg(x) are induced by the electron concentration, which decreases with increasing x. The stability of the different Laves phase structures as a function of electron concentration was analyzed by the method of moments.
69 citations
TL;DR: In this article, the magnetic moment of nickel in the polycrystal GdNi 2 Laves phase was investigated by means of magnetic circular dichroism (MCD) in the core-level x-ray-absorption spectroscopy.
Abstract: Investigation of the magnetic moment of nickel in the polycrystal GdNi 2 Laves phase was carried out by means of magnetic circular dichroism (MCD) in the core-level x-ray-absorption spectroscopy. It was revealed that the nickel magnetic moment originating from the 3d state (band) does exist and couples antiparallel to that of gadolinium whose MCD was observed at the M 4 , 5 absorption edge. That is, nickel retains an intrinsic magnetic moment even in the Laves phase concentration. Furthermore, by analyzing in terms of sum rule, the contribution of spin and orbital magnetic moments to the magnetic moment was evaluated and discussed.
61 citations
TL;DR: In this paper, the Mo-Zr binary system was optimized using the available experimental data on the phase diagram and two estimated enthalpy values, one for the formation of the Laves phase and another for the m...
Abstract: The Mo-Zr binary system has been optimized using the available experimental data on the phase diagram and two estimated enthalpy values, one for the formation of the Laves phase and one for the m ...
60 citations
TL;DR: In this article, the microstructure and constitution of Fe-Al-M-C (M=Ti, V, Nb, Ta) alloys with strengthening carbides and Laves phase are investigated.
50 citations
TL;DR: In this paper, the structural and thermodynamic properties of RM3-type compounds are reviewed and discussed in relation with other ternary systems, and the results on new RM 3-type systems are discussed.
48 citations
25 May 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the influence of thermal deformation history on the evolution of secondary phases in P91 steel annealed at 853, 893, and 923 K was studied by means of transmission electron microscopy.
Abstract: The influence of thermal-deformation history on the evolution of secondary phases in P91 steel annealed at 853, 893, and 923 K was studied by means of transmission electron microscopy. Calculations of phase equilibria for a Fe–Cr–V–Mo–Ni–Nb–Mn–N–C system corresponding to the investigated steel were also carried out. The calculations were performed using the thermodynamic database program Thermo - Calc. M 23 C 6 and MX phases were identified experimentally in all conditions investigated. Laves phase was only found in conditions annealed for longer times at 853 and 893 K and in the non-deformed condition annealed at 923 K per 1000 h. The thermodynamic calculations revealed M 23 C 6 and MX as equilibrium phases at 853, 893, and 923 K. The discrepancy between experimental and calculated results concerning the Laves phase indicates that either the investigated steel has not achieved equilibrium after aging for 5000 h at 853 and 893 K or the thermodynamic model for this phase should be modified. Also the temperature dependencies of the Cr/Fe ratio for M 23 C 6 carbide showed opposite tendencies for originally deformed and non-deformed conditions.
38 citations
TL;DR: In this paper, the properties of NbCr2 and ZrCr2 Laves phase alloys were investigated in terms of alloying, heat treatment and alloy stoichiometry.
Abstract: Microstructures, mechanical properties and oxidation behavior were investigated on NbCr2 and ZrCr2 Laves phase alloys prepared by powder metallurgy (P/M), and also by arc-melting, i.e. ingot metallurgy (I/M). These properties were also evaluated, in terms of alloying, heat treatment and alloy stoichiometry. High-temperature yield strength and brittle ductile transition temperature (BDTT) were generally lower in alloys prepared by P/M process than in those prepared by I/M process while micro hardness and fracture toughness were higher in alloys prepared by P/M process than in those prepared by I/M process, irrespective of NbCr2 or ZrCr2 alloys. Also, high-temperature strength and micro hardness were higher in NbCr2 alloys than in ZrCr2 alloys while fracture toughness was lower in NbCr2 alloys than in ZrCr2 alloys, irrespective of P/M or I/M process. For oxidation behavior at 1223 K, NbCr2 alloys showed linear increase with increasing time accompanied with irregular fluctuation, while ZrCr2 alloys showed parabolic increase with increasing time. It was also found that alloy stoichiometry greatly affected micro hardness, fracture toughness and oxidation behavior in ZrCr2 alloys.
35 citations
TL;DR: In this article, the free energy changes for the precipitation reactions from niobium-supersaturated ferrite have been obtained by using the solubility products of Fe 3 Nb 3 C and Fe 2 Nb, both of which are prominent precipitates in such steels.
Abstract: Precipitation behaviors in niobium alloyed ferritic stainless steels, which are widely used as heat resistant materials in automotive exhausts, were investigated. The solubility products of Fe 3 Nb 3 C and Fe 2 Nb, both of which are prominent precipitates in such steels, were experimentally obtained. The expressions of the solubility products with mass% are given by: Fe 3 Nb 3 C; log 10 {(Nb] 3 [C]}=-11 613/T+5.2178 Fe 2 Nb; log 10 [Nb]=-3 780.3/T+2.4646 These were verified with some published experimental data. An attempt was also made to get thermodynamic parameters using the solubility products. The free energy changes for the precipitation reactions from niobium-supersaturated ferrite have been obtained. The expressions with mole fractions in ferrite matrix, e.g. x αβ Nb, are given by: Fe 3 Nb 3 C (β); ΔG β =-222 509- RT{6.423+ln(x αβ Nb) 3 (x αβ c)} Fe 2 Nb (ω); ΔG ω = -72 334- RT{0.5469+ln N αω Nb}.
15 Mar 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, microstructural development after long term aging and its effect on the mechanical properties have been investigated in Ti-6Al-2Cr-2Mo-2Sn-2Zr alloy, four types of precipitates have been identified in the alloy, they are α 2 -Ti 3 Al, ω, silicides and α-TiCr 2 Laves phase.
Abstract: Microstructural development after long term aging and its effect on the mechanical properties have been investigated in Ti–6Al–2Cr–2Mo–2Sn–2Zr alloy. Four types of precipitates have been identified in the alloy, they are α 2 -Ti 3 Al, ω, silicides and α-TiCr 2 Laves phase. α 2 -Ti 3 Al and ω are observed in the as-received materials and all aged samples. Silicides, (Ti, Zr) x Si 3 (5≤ x ≤6), are found in the specimens aged at 550–650 °C over 500 h. The silicides have a hexagonal structure with a lattice parameter: a =7.01±0.03, c =3.63±0.06 A. The orientation relation between the silicides and the parent β-phase has been determined as: [111] β //[0001] silicide , (101) β //(1100) silicide . Laves phase α-(Ti, Zr)Cr 2 is observed in the samples aged at 450–550 °C over 500 h. It has a cubic structure ( a =7.12±0.03 A) with an orientation relationship with the α- and β-Ti matrix: [110] α-TiCr 2 //[0001] α-Ti //[110] β-Ti , ( 1 13) α - TiCr 2 //( 1 100) α - Ti //( 1 10) β - Ti . Long term aging in the temperature range of 450–550 °C results in significant decrease of fracture toughness and increase of intergranular failure, due to precipitation of α 2 -Ti 3 Al and α-(Ti, Zr)Cr 2 Laves phase. No considerable change in fracture toughness for the samples aged at 650 °C up to 1000 h is found in spite of precipitation of the α 2 -Ti 3 Al and the silicides. The retention of fracture toughness after aging at these temperatures has been attributed to coarsening of secondary α-Ti platelets during the aging treatment.
TL;DR: In this article, phase equilibria were established in the Ti-Fe-Sb ternary system below the TiSb2-FeSb section at 1070 K; the Sb-TiSb 2-Fe Sb region was studied at 870 K. The phase relations were based on X-ray diffraction experiments on arc-melted bulk alloys, which were annealed up to 350 h.
TL;DR: In this paper, the adiabatic temperature change and the isothermal magnetic entropy change upon magnetic field variations in the Laves phase pseudobinary (Er 1− c Dy c )Co 2.
TL;DR: In this paper, the Laves phase structure in three Cr-based two-phase alloys, Cr-12Nb, Cr 8Zr and Cr 2Nb-1Zr, was characterized using transmission electron microscopy.
TL;DR: In this paper, a new alloy with high hydrogen storage capacity, partial Cr in TiCr1.8 was substituted by V-Fe alloy and X-ray diffraction and metallography observation proved that the substitution did not change the phase constitution of TiCr 1.6.
TL;DR: In this article, the electrochemical properties of the ( Ti 08 Zr 02 )( V 0533 Mn 0107 Cr 016 Ni 2 ) x (x=2,3,4,5,6) hydrogen storage electrode alloys have been studied X-ray powder diffraction analysis showed that all alloys mainly consisted of a C14 Laves phase with hexagonal structure and a V-based solid solution phase with BCC structure.
TL;DR: In this paper, a new amorphous Ti16.6Ni20Cu20A110 alloy was developed using the novel equiatomic substitution technique, which can form a fine-scale distribution of 2-5 nm nanocrystals and the supercooled liquid region increases to ΔT=108°C.
Abstract: A new amorphous Ti16.6Zr16.6Hf16.6Ni20Cu20A110 alloy has been developed using the novel equiatomic substitution technique. Melt spinning Ti16.6Zr16.6Hf16.6Ni20Cu20A110 forms an amorphous phase with a large supercooled liquid region, ΔT=70°C. After isothermal annealing within the supercooled liquid region for 3 h at 470°C, the amorphous alloy crystallizes to form a fine-scale distribution of 2–5 nm nanocrystals, and the supercooled liquid region increases to ΔT=108°C. Atomic-scale compositional analysis of this partially crystalline material using a three-dimensional atom probe (3DAP) is unable to detect any compositional difference between the nanocrystals and the remaining amorphous phase. After annealing for 1 hr at 620°C, the amorphous alloy crystallizes to form 20–50nm equiaxed grains of a hexagonal-type C14 Laves phase with lattice parameters a = 5.2A and c = 9.0 A. 3DAP analysis shows that this Laves phase has a composition very close to that of the initial amorphous phase, suggesting that the alloy...
TL;DR: In this article, the effects of V- or Zr-addition and fluorination on the discharge capacity of AB5-type alloy with a multicomponent La-Ni-Al-Co-Mn-My (M=V, Zr; y=0.02, 0.05, 0 1, 0 2, 0 3) system were investigated.
TL;DR: In this paper, the structural properties of the system La 1− x Ce x Y 2 Ni 9 with x Ce = 0, 0.5 and 1 have been investigated by electron probe microanalysis, powder X-ray diffraction and absorption spectroscopy.
TL;DR: The possibility of the composition anisotropy compensating in Dy1-xPrxFe2 is discussed phenomenologically, based on a single ion approach as mentioned in this paper, and the crystal structure, the easy magnetization direction, and the spontaneous magnetostriction of Tb02Dy08-exPrx(Fe09B01)(193) (0less than or equal toxless than and or equal to07) alloys are studied.
Abstract: The possibility of the composition anisotropy compensating in Dy1-xPrxFe2 is discussed phenomenologically, based on a single ion approach The crystal structure, the easy magnetization direction, and the spontaneous magnetostriction of Tb02Dy08-xPrx(Fe09B01)(193) (0less than or equal toxless than or equal to07) alloys are studied Single-phase Tb02Dy08-xPrx(Fe09B01)(193) with cubic MgCu2-type structure forms up to x=04 and the magnetostrictive phase exists in all the alloys studied A single (440) peak of x-ray diffraction of the Laves phase exists when 0less than or equal toxless than or equal to03, but becomes doubly split when 04less than or equal toxless than or equal to07 because of a large spontaneous magnetostriction along its easy magnetization direction Composition anisotropy compensation is realized in Tb02Dy08-xPrx(Fe09B01)(193) alloys Tb02Dy04Pr04(Fe09B01)(193) alloy with the single Laves phase has a large magnetostriction (lambda(111)approximate to1200 ppm) and a low anisotropy, which may be a good candidate material for magnetostriction application (C) 2003 American Institute of Physics
TL;DR: In this article, the effect of matrix substructures on the Laves phase precipitation in Fe-Cr-Nb-Ni system was examined during isothermal aging up to 1 000 h at 873 and 973 K.
Abstract: In order to make clear the effect of matrix substructures on the Laves phase precipitation in Fe-Cr-Nb-Ni system, age hardening behavior was examined during isothermal aging up to 1 000 h at 873 and 973 K and the precipitation morphology of the Laves phase was investigated by transmission electron microscopy (TEM). The microstructures of Fe-10Cr-1Nb and Fe-15Cr-1Nb (mol%) alloys with ferrite matrix contain high density of rod-shaped Laves phase which precipitates within the ferrite grains during aging. On the other hand, in the Fe-10Cr-1Nb-1Ni alloy with massive ferrite matrix, most of the Laves phase precipitates in subgrain boundaries. Additionally the deformed ferrite matrix has been prepared for examining the effect of dislocation density on morphology of the Laves phase. It is found that the difference of matrix substructures between the ferrite and deformed ferrite provides the different number and distribution of nucleation sites for precipitation of the Laves phase. Mechanical properties were evaluated by tensile tests conducted at room temperature, 873 and 973 K.
TL;DR: In this paper, the effects of titanium on the crystalline structure and electrochemical properties of Zr-based AB 2 electrode alloys were investigated using scanning electron microscopy (SEM) and XRD and Rietveld analysis.
TL;DR: In this paper, the normalized pressure dependence method (NPDM) was applied to interpret the experimental data and compare with each other for commercial hydride forming alloys C2, C51 and C52 with Laves phase structure.
TL;DR: In this paper, a fine, three-phase structured coating layer was suggested to suppress degradation due to both mutual diffusion and cracking in a Ti-50at.% alloy, which consisted of a three layer structure: an outermost TiAl 2 (τ phase), outer TiAl (Al-rich γ-phase), and intermediate γ, β, and Laves phase layers.
TL;DR: The phase fields of the Laves phase in the Cr-Zr-Nb and Cr-zr-Hf alloy systems were investigated at 1573 K in this article.
TL;DR: In this article, the effects of additional elements to the Ti-Cr alloys on their protium absorption-desorption properties were investigated, and it was found that the addition of V, Mo, W, Nb, Ta, Ru, Rh, Re, Os, Ir etc.
TL;DR: A broad bulk quasicrystal-forming region was identified in the Ti-Zr-Ni system as discussed by the authors, which can be obtained by using a conventional suction-casting method.
Abstract: A broad bulk-quasicrystal-forming region, (Ti x Zr100− x )100− y Ni y (43.75 ≤ x ≤ 81.25, 17 ≤ y ≤ 23), has been identified in the Ti-Zr-Ni system, and quasicrystals can be obtained by using a conventional suction-casting method. The quasilattice constant of the icosahedral (i) phase is within the range 0.505-0.530 nm. Ti40Zr40Ni20 is the optimal composition, where nearly pure bulk quasicrystals can be obtained. With a slight deviation from this composition, Ti-Zr solid-solution phases and/or C14-type Laves phase, although minority phases, coexist with the majority i phase. Differential thermal analysis reveals that the i phase in the bulk as-cast Ti40Zr40Ni20 alloy is stable below 953 K and transforms to the C14-type Laves phase and β-Ti-Zr solid solution at higher temperatures.
TL;DR: In this article, it was shown that particles of M6C in CrMoV low alloy steels can influence phosphorus grain boundary segregation in a similar manner to Laves phase particles in 12CrMoV steel.