Phase equilibria in the Mg-rich corner of the Mg-Zn-La system at 350℃

The phase equilibria in the Mg-rich comer of the Mg-Zn-La system at 350℃ have been investigated by scanning electron microscopy, X-ray diffraction, and electron probe microanalysis. It has been shown that the linear compound （Mg,Zn）17La2 existed in the Mg-Zn-La system at 350℃. The linear cornpound （so-called Tphase） was with the C-centred orthorhombic crystal structure induced by the solution of significant quantities of the third element. The three-phase region α（Mg） ＋ MgZn（La） ＋ T and the two-phase region composed of the α（Mg） and the linear-compound T phase existed in the Mg-rich comer of the Mg-Zn-La system at 350℃.     

Isothermal section at 927℃ of Cr-Ni-Ti system

The isothermal section at 927℃ of the Cr-Ni-Ti system was established using a high-efficiency diffusion couple approach, supplemented with eight equilibrated alloys. The alloy compositions were selected on the basis of the experimental results from the diffusion couple. Both the diffusion couple specimens and the alloys were examined by means of optical microscopy, scanning electron microscopy, and electron probe microanalysis. No ternary compound is found at 927℃. The following five three-phase equilibria are well determined： TiNi3＋（Cr）＋（Ni）, TiNia＋（Cr）＋TiNi, TiNi＋（Cr）＋Cr2Ti, Ti2Ni＋Cr2Ti＋TiNi and Ti2Ni＋Cr2Ti＋（Ti）. The solubilities of Cr in NiTi2, NiTi, and Ni3Ti are determined to be 7.5%, 14.5% and 11.4% （molar percent）, respectively, α-Cr2Ti and β-Cr2Ti dissolve about 9.2% and 13.9% Ni （molar percent）, respectively.     

Determination of isothermal section of Fe-Ti-Zr ternary system at 1173 K

Phase relations in the Fe-Ti-Zr ternary system at 1173 K were investigated by means of diffusion-triple approach together with electron probe microanalysis（EPMA） technique. A series of tie lines and tie-triangles were determined and the isothermal section at 1 173 K was established, which consists of four three-phase fields： β（Ti, Zr）＋FeZr2＋FeTi, FeZr2＋FeTi＋Fe2Zr, FeTi ＋Fe2Zr ＋Fe2Ti and Fe2Zr ＋Fe2Ti ＋Fe. The results show that the largest solubility of Ti in Fe2Zr is about 11.3 %（mole fraction） and the solid solubility of Ti in FeZr2 is about 26.9%, the solid solubility of Zr in Fe2Ti is about 8.1% and the solid solubility of Zr in FeTi is 7.2%. The binary compound FeZr2 is nearly a linear compound. No ternary compound is found.     

Phase equilibria in the Mg-rich corner of the Mg-Zn-La system at 350°C

1. Introduction Mg-based alloys are attractive for applications because of the light weight and a high specific strength. Among the common alloying elements, the addition of zinc could make the magnesium alloys strengthen by precipitation [1-2]. The further addi- tion of the rare-earth elements to the Mg-Zn alloys is more effective on the precipitation-strengthening [3-4]. But phase diagrams of the Mg-Zn-RE system, as the basis of the alloying, have hardly been built up [5-6]. The phase equ…     

Partial phase relationships of Mg-Zn-Ce system at 350℃

The alloys were prepared in Mg-rich corner of Mg-Zn-Ce system. Partial phase equilibrium relationships of these alloys at 350 ℃ were identified by using scanning electron microscopy(SEM), electron probe microanalysis(EPMA), X-ray diffraction(XRD) analysis and selected area electron diffraction(SAED) pattern analysis of transmission electron microscopy(TEM). Partial isothermal section of Mg-Zn-Ce system in Mg-rich corner was identified. The results show that there is one ternary compound (T-phase) in Mg-Zn-Ce system. The T-phase is a linear ternary compound in which the content of Ce is about 7.7% (molar fraction); while the content of Zn is changed from 19.3% to 43.6% (molar fraction). The crystal structure of T-phase is C-centered orthorhombic. In addition, one two-phase region of Mg+T-phase and one three-phase region of Mg+T-phase+MgZn(Ce) exist in the Mg-rich corner of Mg-Zn-Ce system at 350 ℃.     

1100℃ isothermal section of Nb-W-Zr-C quaternary system

An isothermal section of the Nb-W-Zr-C system at 1100℃ was established by means of multiphase diffusion couples along with electron microprobe analysis and X-ray diffraction analysis. The isothermal section consists of two single-phase regions, a(Nb, W, Zr) and (W, Nb)2Zr and one double-phase region, a(Nb, W, Zr) (W, Nb)2Zr. It is concluded that (W, Nb)2Zr is an interstitial intermediate phase with the face-centered eubie (Cu2Mg) lattices. The maximum solid solubility of carbon in (W, Nb)2Zr phase is determined as about 4.18%C (mole fraction). The composition ranges of tungsten in the (W, Nb)2Zr phase are 55.41% to 65.98% and the maximum solid solubility of niobium in (W, Nb)2Zr is determined as 7.78%.     

Primary study of the isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ in air

The isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ was reported for the samples which were prepared from sol-gel method and quenched by water after being heated at 1150℃ for 12 h. Based on the conventional X-ray powder diffraction （XRD） and in situ high-temperature XRD quantitative analysis,in addition to scanning electron microscopy measurement,the phase identification was achieved. Combining the deduction from the component phase diagrams of the binary systems using the phase equilibrium theorem,the primary isothermal phase diagram was plotted over the composition area Cu2O-mullite-SiO2. In this area,the approximate composition areas of two two-phase regions and one three-phase region,（L2＋Cr）,（L2＋M）,and （L1＋L2＋Tr）,were determined. Moreover,the precise composition areas of both of the three-phase regions （L2＋Cr＋M） and （L2＋M＋A） were determined according to the results of conventional and in situ high-temperature XRD quantitative analysis by Rietveld method.     

Isothermal section (500 ℃) of phase diagram of Nd-Al-Si ternary system

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＡｌ Ｓｉｅｑｕｉｌｉｂｒｉｕｍ ｐｈａｓｅｄｉａｇｒａｍｈａｓｂｅｅｎｓｔｕｄｉｅｄｂｙｍａｎｙｒｅｓｅａｒｃｈｅｒｓ[1～5] .ＮｏｉｎｔｅｒｍｅｔａｌｌｉｃｃｏｍｐｏｕｎｄｗａｓｄｉｓｃｏｖｅｒｅｄｉｎＡｌ Ｓｉｂｉｎａｒｙｓｙｓｔｅｍ .ＴｈｅｓｏｌｕｂｉｌｉｔｙｏｆＳｉｉｎＡｌｉｓ0 .80 % ( 0 .77% ,ｍｏｌｅｆｒａｃｔｉｏｎ) ,ＡｌｉｓｉｎｓｏｌｕｂｌｅｉｎＳｉａｔ 50 0℃[1 ] .Ｈｏｗｅｖ ｅｒ ,Ｅｌｌｉｏｔｔ[2 ] ｒｅｐｏｒｔｅｄｔｈａｔｔｈｅｓｏｌｕｂｉｌｉｔｙｏ…     

Phase equilibria of low-Y side in Mg-Zn-Y system at 400℃

Phase equilibrium relations of the Mg-Zn-Y system in the low-Y side at 400℃were investigated by alloy-equilibrated method,combined with thermal analysis.The results show that there is a liquid phase which could be in equilibrium with an a-Mg solid solution and an icosahedral quasicrystal I phase in the low-Y side of the Mg-Zn-Y system at 400℃.The liquid phase region originates from the binary Mg-Zn system and extends to 0.4 at%Y in the Mg-Zn-Y system.Besides,the hexagonal structure H phase,fee W...     

Isothermal section of Al–Ti–Zr ternary system at 1073 K

Through alloy sampling combined with diffusion triple technique, phase equilibria in Al–Ti–Zr ternary system at 1073 K were experimentally determined with electron probe microanalysis (EPMA). Experimental results show that there is a solid solution β(Ti,Zr) which dissolves Al up to 16.3% (mole fraction). Ti and Zr can substitute each other in most Ti–Al and Al–Zr binary intermediate phases to a certain degree while the maximum solubility of Zr in Ti₃Al and TiAl reaches up to 17.9% and 4.0% (mole fraction), respectively. The isothermal section consists of 16 single-phased regions, 27 two-phased regions and 14 three-phased regions. No ternary phase was detected.     

Isothermal section of the Er–Fe–Al ternary system at 800 °C

Physico-chemical analysis techniques, including X-ray diffraction and Scanning Electron Microscope–Energy Dispersive X-ray Spectroscopy, were employed to construct the isothermal section of the Er–Fe–Al system at 800 °C. At this temperature, the phase diagram is characterized by the formation of five intermediate phases, ErFe_12?xAl_x with 5 ≤ x ≤ 8 (ThMn₁₂-type), ErFe_1+xAl_1?x with ?0.2 ≤ x ≤ 0.75 (MgZn₂-type), ErFe_3?xAl_x with 0.5 < x ≤ 1 (DyFe₂Al-type), Er₂Fe_17?xAl_x with 4.74 ≤ x ≤ 5.7 (TbCu₇-type) and Er₂Fe_17?xAl_x with 5.7 < x ≤ 9.5 (Th₂Zn₁₇-type), seven extensions of binaries into the ternary system; ErFe_xAl_3?x with x < 0.5 (Au₃Cu-type), ErFe_xAl_2?x with x ≤ 0.68 (MgCu₂-type), Er₂Fe_xAl_1?x with x ≤ 0.25 (Co₂Si-type), ErFe_2?xAl_x with x ≤ 0.5 (MgCu₂-type), ErFe_3?xAl_x with x ≤ 0.5 (Be₃Nb-type), Er₆Fe_23?xAl_x with x ≤ 8 (Th₆Mn₂₃-type), and Er₂Fe_17?xAl_x with x ≤ 4.75 (Th₂Ni₁₇-type) and one intermetallic compound; the ErFe₂Al₁₀ (YbFe₂Al₁₀-type).     

Phase equilibria of low-Ni side in Nb-Ni-Ti system at 1100℃

The phase equilibria related to liquid phase in low-Ni side of Nb-Ni-Ti system at 1100℃ were investigated through scanning electron microscope(SEM),electron probe micro-analyzer(EPMA),X-ray diffraction(XRD) and differential scanning calorimetry(DSC).The results show that there exists liquid phase in equilibrium with continuous solid solution(Nb,βTi) and compound TiNi in low-Ni side of Nb-Ni-Ti system at 1100℃.The liquid phase region originates from low-Ni side of binary TiNi system and extends t...     

Isothermal oxidation behavior of Ti3Al-based alloy at 700-1000℃ in air

The isothermal oxidation behavior of a Ti3Al-based alloy (Ti-24Al-14Nb-3V-0.5Mo-0.3Si, molar fraction, %) at 700- 1 000 ℃ in air was investigated. The oxidation kinetics of tested alloy approximately obeys the parabolic law, which shows that the oxidation process is dominated by the diffusion of ions. The oxidation diffusion activity energy is 241.32 kJ/mol. The tested alloy exhibits good oxidation resistance at 700 ℃. However, when the temperature is higher than 900 ℃, the oxidation resistance becomes poor. The XRD results reveal that the oxide product consists of a mixture of TiO2 and Al2O3. Serious crack and spallation of oxide scale occur during cooling procedure after being exposed at 1 000 ℃ in air for 16 h. According to the analysis of SEM/EDS and XRD, it is concluded that the Al2O3 oxide forms at the initially transient oxidation stage and most of it keeps in the outer oxide layer during the subsequent oxidation procedure.     

The isothermal section at 400°C of the Nd–Cu–Sn ternary system

The Nd–Cu–Sn isothermal section at 400°C has been investigated by means of X-ray diffraction, optical and scanning electron microscopy and electron probe microanalysis. The following compounds have been identified or confirmed: NdCu₅Sn, Nd₇Cu₃₅Sn₁₁, NdCu₉Sn₄, NdCuSn, Nd₃Cu₄Sn₄, NdCu₂Sn₂, Nd₂Cu₃Sn₆ and NdCu_1−ySn₂, and their crystal structure have been determined or revised. Single crystal structure determination of the phases Nd₇Cu₃₅Sn₁₁ and Nd₃Cu₄Sn₄ and full profile powder refinement of the compound Nd₂Cu₃Sn₆, previously suggested as Nd₂Cu₄Sn₅, are also given. The subdivision of the composition triangle in tie triangles has been nearly completed. Of the predicted 36 three-phase equilibria, thirty have been defined. The general characteristics of the section have been discussed in comparison with those of other R–Cu–Sn systems formed by light rare earths (R= Ce, Pr).     

The isothermal section at 400 °C of the Pr–Ag–Sn ternary system

The phases and equilibria involved in the isothermal section at 400 °C of the Pr–Ag–Sn ternary system have been here investigated after different annealing times by X-ray diffraction, optical and scanning electron microscopy and electron probe microanalysis. Three ternary compounds have been confirmed: PrAgSn hP6 LiGaGe type, Pr₃Ag₄Sn₄ oI22 Gd₃Cu₄Ge₄ type and Pr₅AgSn₃ hP18 Hf₅CuSn₃ type. The solid solubility ranges of the binary compounds have been considered and trends of their lattice parameters studied. The tie-triangles of the ternary system have been defined. The general features of the section are discussed and compared to those of the other R–Ag–Sn ternary systems.     

Isothermal Sections in the Mg-Corner of Mg-Er-Sn Ternary System at 300, 400 and 500 °C

The phase equilibria in the magnesium (Mg) rich corner of the Mg-Er-Sn ternary system at 300, 400 and 500 °C have been determined through key alloy method by means of x-ray diffraction and scanning electron microscopy with assistance of energy dispersive spectroscopy. The results show that in the composition range of our studied, each isothermal section consists of five single-phase regions, seven two-phase regions, and three three-phase regions, four compounds, i.e. Mg₂Sn, ErMgSn, Er₅Sn₃ and Er₅Mg₂₄ are found in equilibrium with the Mg solid solution. The homogeneity ranges of Mg solid solution as well as the solid solubilities of the intermediate phases at different temperatures are reported.     

Phase equilibria in Mg-rich corner of Mg–Ca–RE (RE=Gd,Nd) systems at 400 °C

The phase equilibria in Mg-rich corner of Mg–Ca–Gd and Mg–Ca–Nd ternary systems at 400 °C were determined through the equilibrated alloy method by using XRD, SEM, EPMA and DSC. Partial isothermal sections in Mg-rich corner of Mg–Ca–Gd and Mg–Ca–Nd ternary systems at 400 °C were constructed from 13 alloys. A three-phase region of α–Mg, Mg₄₁RE₅ and Mg₂Ca was determined in both ternary systems. It is formed by a similar ternary eutectic reaction L→α-Mg+Mg₂Ca+Mg₄₁RE₅ at 499.6 °C and 505.6 °C, respectively. It is found that the maximum solubility of Ca in Mg₅Gd is 3.68% (molar fraction) and 3% of Gd can be dissolved in Mg₂Ca in the Mg–Ca–Gd system at 400 °C. While in the Mg–Ca–Nd system the maximum solubility of Ca in Mg₄₁Nd₅ is 3.57% and 1.24% of Nd can be dissolved in Mg₂Ca at 400 °C. Other three-phase equilibria existing in Mg-rich corner of Mg–Ca–Gd system are α-Mg+Mg₅Gd+T and Mg₅Gd+Mg₂Ca+T and the three-phase equilibrium in Mg-rich corner of Mg–Ca–Nd system is Mg₃Nd+Mg₂Ca+ Mg₄₁Nd₅.     

The Y–Cu–Mg system in the 0–66.7 at.% Cu concentration range: The isothermal section at 400 °C

Synthesis and characterization of about fifty alloys were performed in order to construct the isothermal section of the Y–Cu–Mg ternary system at 400 °C in the 0–66.7 at.% Cu concentration range. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS) and X-ray powder diffraction (XRPD) techniques were used to examine microstructures, identify phases and define their compositions and crystal structures. Phase equilibria in the investigated compositional region are characterized by the absence of extended ternary solid solutions and by the presence of at least ten ternary phases. Crystal structures of the previously reported Y₂Cu₂Mg, Y₅Cu₅Mg₈, Y₅Cu₅Mg₁₃, Y₅Cu₅Mg₁₆ and YCuMg₄ phases were confirmed. A ternary phase with homogeneity range around the YCu₄Mg stoichiometry was found, crystallizing in the cF24--MgCu₄Sn structure type; at 400 °C this phase coexists with a ternary solid solution based on the binary Laves phase Cu₂Mg, which dissolves about 5 at.% Y. The equiatomic YCuMg phase was also found to exist: from the analysis of X-ray powder patterns it is suggested to crystallize in the hP9--ZrNiAl structure type (a = 0.74449(4) nm, c = 0.39953(2) nm). Two other stoichiometric ternary phases were detected, of approximate compositions Y₂₅Cu₁₈Mg₅₇ and Y₁₃Cu₉Mg₇₈, whose crystal structures are still unknown. In the Mg-rich region, a ternary phase forms characterized by a large homogeneity region.