Phase relationships of the Pr-Co-Fe system at 773 K

The Phase equilibrium of the ternary Pr-Co-Fe system at 773 K was investigated by means of X-ray powder diffraction (XRD), Rietveld method and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy. Nine binary compounds, i.e., Pr₂Co₁₇, PrCo₅, Pr₂Co₇, PrCo₃, PrCo₂, Pr₄Co₃, Pr₅Co₂, Pr₃Co and Pr₂Fe₁₇ was confirmed to exist, The maximum solubility of Fe in binary compounds Pr₂Co_17, PrCo₅, Pr₂Co₇, PrCo₃, PrCo₂, Pr₄Co₃ and Pr₃Co was determined to be 76.3, 14.1, 15.5, 20.7, 37.5, 2.3 and 2.9 at.%, respectively. No ternary compound was found.     

Phenomenological model for the formation of heterogeneous tracks in pyrochlores irradiated with swift heavy ions

Zirconate and titanate pyrochlores were irradiated with swift heavy ions in order to investigate the effects of the chemical composition on the structural changes induced by high electronic excitation. Both transmission electron microscopy and X-ray diffraction results show that the structural modifications induced by irradiation with 120-MeV U ions are strongly dependent on the sample composition: Gd₂Ti₂O₇ is readily amorphized, whereas Gd₂Zr₂O₇ is transformed into a radiation-resistant anion-deficient fluorite structure. For Sm₂Zr₂O₇, Eu₂Zr₂O₇ and Nd₂Zr₂O₇, more complex behavior is observed, since both pyrochlore-fluorite phase transformation and amorphization occur. A new phenomenological model (the heterogeneous track overlap model, HTOM), which assumes a direct impact mechanism coupled with a single track overlap process, is proposed to describe the formation of heterogeneous track structures consisting of mixed anion-deficient fluorite and amorphous domains. The pyrochlore composition mainly influences the structure of ion tracks (and weakly their diameter), and essentially concerns the amount of amorphous phase vs the amount of fluorite counterpart.     

Phase transformation in a dental Pd---Cu---Ga alloy

Phase transformation behavior in a dental Pd---Cu---Ga alloy was studied by means of hardness tests, electrical resistivity measurements, X-ray diffraction and transmission electron microscopy. Annealing at 673 K produces two hardness peaks which correspond to the formation of a metastable phase with ordered fet structure and the precipitation of the equilibrium phases, ₁(fcc) + ₂(fcc) + Pd₂Ga (orthorhombic), respectively. On the other hand, annealing at 873 K exhibits only one peak due to the precipitation of the equilibrium phases. The difference of the phase transformation between both annealings is interpreted in terms of the free energy.     

Phase diagram of the quasi-binary system TlInSe2-SnSe2

The TlInSe₂-SnSe₂ quasibinary system was investigated using differential thermal and X-ray phase analysis methods. The phase diagram is of eutectic type (V type of the Rozeboom classification). The solid solution range of the ternary compound in the TlInSe₂-SnSe₂ system extends to 28 mol.% SnSe₂ at 670 K. The eutectic point coordinates are 63 mol.% SnSe₂ and 788 K.     

Synthesis, structural and microwave dielectric properties of Al2W3−xMoxO12 (x = 0-3) ceramics

Low dielectric ceramics in the Al₂W_3−xMo_xO₁₂ (x = 0-3) system have been prepared through solid state ceramic route. The phase purity of the ceramic compositions has been studied using powder X-ray diffraction (XRD) studies. The microstructure of the sintered ceramics was evaluated by Scanning Electron Microscopy (SEM). The crystal structure of the ceramic compositions as a result of Mo substitution has been studied using Laser Raman spectroscopy. The microwave dielectric properties of the ceramics were studied by Hakki and Coleman post resonator and cavity perturbation techniques. Al₂Mo_xW_3−xO₁₂ (x = 0-3) ceramics exhibited low dielectric constant and relatively high unloaded quality factor. The temperature coefficient of resonant frequency of the compositions is found to be in the range −41 to −72 ppm/°C.     

Phase transformation and microstructural changes during ageing process of an Ag–Pd–Cu–Au alloy

Age-hardening behaviour and the related phase transformation and microstructural changes during isothermal ageing process were studied to elucidate the age-hardening mechanism of an Ag-based dental casting alloy composed of Ag–Pd–Cu–Au–Zn, Ir and In by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) observations and energy dispersive spectroscopic microanalysis (EDS). In the hardness test at 350 and 400 °C, the hardness of the solution-treated specimen began to increase and reached a maximum value with increasing ageing time, and subsequently the hardness decreased gradually. By considering XRD results and SEM observations together, the solution-treated specimen consisted of three phases, the Ag-rich α₁ phase as a matrix, the Cu–Pd α₂ phase and the CuPd β phase with a CsCl-type as particle-like structures. By ageing the solution-treated specimen, the Ag-rich α₁ and Cu–Pd α₂ phases were transformed into the Ag-rich α^′₁ and Cu₃Pd α^′₂ phases, respectively. The CuPd β phase with a CsCl-type was not changed apparently during the ageing process. From the results of the hardness test, XRD study, SEM observations and EDS analysis, it could be derived that the hardness increased by the diffusion and precipitation of the Cu-rich phase from the Ag-rich matrix during the early stage of phase transformation of α₁ into α^′₁ and that the progress of coarsening of the Cu-rich precipitates with an entanglement structure caused the hardness decrease during the later stage of phase transformation of α₁ into α^′₁. The particle-like structures composed of the Cu–Pd α₂ and the CuPd β phase with a CsCl-type contributed little to the hardness increase which occurred in the early stage of aging process.     

Isothermal section of the Al-Dy-Zr ternary system at 773 K

The phase relations in the Al-Dy-Zr ternary system at 773 K have been investigated by X-ray powder diffraction (XRD) and scanning electron microscope (SEM) with energy disperse X-ray spectroscopy (EDX) in backscattered electron imaging (BSE) modes. The isothermal section at this temperature is featured with 17 single-phase regions, 32 two-phase regions and 16 three-phase regions. Besides, the ternary compound Al₃₀Dy₇Zr₃ has been confirmed to be existed. The maximum solid solubility of Zr in AlDy₂, Al₂Dy₃, AlDy, Al₂Dy and Al₃Dy at 773 K is determined to be 11.5 at.%, 7.8 at.%, 2.4 at.%, 22.5 at.% and 2.5 at.%, respectively.     

Phase transformations in the Zn–Cd–Sb system

Phase equilibria of the Cd–Sb–Zn system have been investigated by metallographic examinations, DSC, XRD and WDS measurements. At 250 °C, the ternary diagram shows two three-phase fields, (Zn)+(Cd)+Zn₄Sb₃ and (Cd)+ Zn₄Sb₃+(Zn,Cd)Sb. Continuous solid solution has been found between ZnSb and CdSb. Solubility of Cd in Sb₃Zn₄ was determined to be about 43 at.%. A variant of the reaction scheme is proposed for the Cd–Sb–Zn system to understand phase relations observed at 250 °C.     

XRD中扫描速度对物相分析的影响

在XRD中,一般认为扫描速度必须选择合适的值,物相定性分析时,扫描速度不能超过4°/min;物相定量分析时,扫描速度不超过1°/min。笔者利用最新型的D/max2200PC型X射线衍射仪对扫描速度的选择进行了系统研究,认为:物相定性分析时,扫描速度可达16°/min;而物相定量分析时,扫描速度亦可达4°/min。     

Experimental phase diagram of the Ti-Si-Sn ternary system at 473 K

The phase diagram of the ternary system Ti-Si-Sn system at 473 K was investigated by means of powder X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscope (SEM) with energy dispersive analysis (EDX). The isothermal section consists of 14 single phase regions, 26 binary phase regions and 13 ternary phase regions. The 10 binary compounds, namely Ti₃Si, Ti₅Si₃, Ti₅Si₄, TiSi, TiSi₂, Ti₃Sn, Ti₂Sn, Ti₅Sn₃, Ti₆Sn₅, Ti₂Sn₃, have been confirmed at 473 K. Moreover, a ternary phase with the crystal structure of tetragonal W₅Si₃ structure type and I4/mcm space group is confirmed in the Ti-Si-Sn system. The combined results of both EDX and XRD show that the composition of this ternary phase is 60.25-61.03 at.% Ti, 15.01-21.77 at.% Si and balance Sn.     

石灰添加量对平果铝土矿赤泥相变的影响

本文采用X射线分析方法对平果铝土矿溶出赤泥的物相进行了系统分析,得出随着石灰添加量的变化,赤泥的物相也作相应的变化.在赤泥的分析中还发现了一个新相,即含铁水化石榴石.     

Phase constitution near the interface zone of diffusion bonding for Fe3Al/Q235 dissimilar materials

The characteristics of phase constitution near the interface of Fe₃Al/Q235 diffusion bonding are researched by means of scanning electron microscope, X-ray diffraction and transmission electron microscope, etc. The test results indicated that an obvious diffusion transition zone forms near the Fe₃Al/Q235 interface as a result of vacuum diffusion bonding (heating temperature 1050–1080 °C, holding time 60 min and pressure 9.8 MPa). The maximum value of the Al content in the transition zone was 16.6 wt.% (about 28.5 at.%). The micro-hardness in the diffusion transition zone was HM 200–400. The transition zone consists of Fe₃Al and α-Fe(Al) solid solution. There was no brittle phase of high hardness near the diffusion interface. This is favorable to the enhancing of the toughness of Fe₃Al/Q235 diffusion joint.     

热循环对 Cu Zn Al Mn Ni记忆合金中双可逆相变的影响

通过差示扫描量热技术 ,研究了热循环对 Cu- 2 3.6 Zn- 4 .4 7Al- 0 .2 3Mn- 0 .17Ni形状记忆合金中双可逆相变的影响。结果表明 ,X→ M转变温度随热循环的进行而降低 ,而马氏体逆转变的温度几乎不发生变化。     

Physicochemical studies of galvanized steel corrosion in urban,industrial, and marine environments,and corrosion mapping of Karachi city: An important coastal city of the 21st-century modern maritime silk route

The coastal city of Karachi is an imperative part of China–Pakistan Economic Corridor, which is integrated with the modern maritime silk route of the 21st century. This paper presents the corrosion mapping and physicochemical studies of galvanized steel corrosion exposed at the urban, industrial, and marine test sites located in the Karachi coastal city from July 2018 to June 2019. Tests have been performed to determine chloride, sulfur dioxide, time of wetness (TOW), and corrosion rates as per ISO protocols 9223 and 9225, and ASTM standards G1, G50, G140-02, D4458-94, and D2010. All test sites have been assigned the C5+ corrosivity category, based on corrosion rates of the galvanized steel, which is not completely in line with the corrosivity category derived from atmospheric pollutants and TOW values for these test sites. SEM/EDS, XRD, and FTIR have characterized the presence of simonkolleite, hydrozincite, and zincite at nearly all the test sites, whereas gordaite is only detected at the marine test sites. Zinc(I) chlorohydroxysulfate is also observed at an urban test site. This study has furnished a novel product of a galvanized steel corrosion map for Karachi, Pakistan.     

The 473 K isothermal section of the Cu–Ti–Sn ternary system

The phase relationships of the Cu–Ti–Sn ternary system at 473 K have been investigated mainly by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), optical microscopy (OM) and differential thermal analysis (DTA). The isothermal section consists of 17 single-phase regions, 33 two-phase regions and 17 three-phase regions. The existence of 12 binary compounds and 2 ternary compounds, namely Cu₄Ti, Cu₃Ti₂, Cu₄Ti₃, CuTi, CuTi₂, Cu₃Sn, Cu₆Sn₅, Ti₃Sn, Ti₂Sn, Ti₅Sn₃, Ti₆Sn₅, Ti₂Sn₃, CuTi₅Sn₃ and CuTiSn, are confirmed in the Cu–Ti–Sn ternary system at 473 K. No new ternary compound is found. The maximum solid solubility of Cu in Ti₆Sn₅ was approximately 10 at.% Cu.     

The isothermal section of the Ti–Co–Zr ternary system at 773 K

The phase equilibria of the Ti–Co–Zr ternary system at 773 K have been investigated mainly by powder X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive analysis (EDX). The isothermal section consists of 16 single-phase regions, 31 two-phase regions and 16 three-phase regions. There are 11 binary compounds, i.e. CoZr₃, CoZr₂, CoZr, Co₂Zr, Co₂₃Zr₆, Co₁₁Zr₂, TiCo₃, h-TiCo₂, c-TiCo₂, TiCo, Ti₂Co in the system. The existence of two ternary compounds Co₁₀Ti₇Zr₃ and Co₆₆Ti₁₇Zr₁₇ has been confirmed at 773 K. Co₂Zr, CoZr₃ and TiCo have a range of homogeneity. The solubilities of Ti in CoZr was determined to be up to 8.1 at.% Ti.     

Synthesis and luminescence studies of CdSrS nanostructures

Cadmium strontium sulfide nanostructures were synthesized by solid state diffusion method in the presence of sodium thiosulfate. XRD confirmed the presence of CdS and SrS structures in the synthesized samples. TEM micrographs revealed the formation of nearly spherical nanoparticles with grain size in the range 30-40 nm. The PL emission was centred around 532 nm with a shoulder at 468 nm. The PL emission of CdSrS shows a blue shift in comparison to that of CdS. Substantially enhanced photoluminescence emission was observed with the addition of Bi³⁺ as a dopant. The effects of different excitation wavelengths on the PL spectra have also been investigated. It is suggested that the emission processes are linked to divalent Cd ions with broadening resulting due to these ions in being differing ion environments.     

Modification of the Kolmogorov–Johnson–Mehl–Avrami rate equation for non-isothermal experiments and its analytical solution

Avrami’s model describes the kinetics of phase transformation under the assumption of spatially random nucleation. In this paper we provide a quasi-exact analytical solution of Avrami’s model when the transformation takes place under continuous heating. This solution has been obtained with different activation energies for both nucleation and growth rates. The relation obtained is also a solution of the so-called Kolmogorov–Johnson–Mehl–Avrami transformation rate equation. The corresponding non-isothermal Kolmogorov–Johnson–Mehl–Avrami transformation rate equation differs from the one obtained under isothermal conditions only by a constant parameter, which depends only on the ratio between nucleation and growth rate activation energies. Consequently, a minor correction allows us to extend the Kolmogorov–Johnson–Mehl–Avrami transformation rate equation to continuous heating conditions.