Miscibility of NiSi2, FeSi2 and Cu3Si

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2008

Magnetic permeability of Si-rich (FeCoNi)-based nanocrystalline alloy: Thermal stability in a wide temperature range J. Appl. Phys. 113, 17A310 (2013); 10.1063/1.4794718

Journal of Solid State Chemistry, 2001

The reported wide-range nonstoichiometric Ni 1؉x Te 2 , 04 4 x4 40.83, and Ni 1؉x Se 2 , 0.574 4x4 40.92, CdI 2 /NiAs structure type solid solution 5elds have been carefully reinvestigated via electron and X-ray powder di4raction to search for evidence of Ni/vacancy ordering and superstructure phases. In the case of telluride, evidence is thereby found for a Ni 3 Te 4 superstructure phase attempting to condense out at x&0.5 while, in the case of selenide, three quite distinct phases have been identi5ed within the Ni 1؉x Se 2 solid solution 5eld. An intriguing characteristic honeycomb di4use-intensity distribution has also been observed across the solid solution 5eld in the case of the Ni 1؉x Te 2 system. Its presence has been attributed to low frequency phonon modes along certain very speci5c directions of reciprocal space.

Metallurgical and Materials Transactions A, 1998

Ternary alloying of MoSi 2 with adding a series of transition elements was investigated by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). Iron, Co, Ni, Cr, V, Ti, and Nb were chosen as alloying elements according to the AB 2 structure map or the atomic size factor. The studied MoSi 2 base alloys were prepared by the arc melting process from high-purity metals. The EDS analysis showed that Fe, Co, and Ni have no solid solubility in as-cast MoSi 2 , while Cr, V, Ti, and Nb exhibit limited solid solubilities, which were determined to be 1.4 ‫ע‬ 0.7, 1.4 ‫ע‬ 0.4, 0.4 ‫ע‬ 0.1, and 0.8 ‫ע‬ 0.1. Microstructural characterization indicated that Mo-Si-M VIII (M VIII ϭ Fe, Co, Ni) and Mo-Si-Cr alloys have a two-phase as-cast microstructure, i.e., MoSi 2 matrix and the second-phase FeSi 2 , CoSi, NiSi 2 , and CrSi 2 , respectively. In as-cast Mo-Si-V, Mo-Si-Ti, and Mo-Si-Nb alloys, besides MoSi 2 and C40 phases, the third phases were observed, which have been identified to be (

Journal of Electronic Materials, 2011

The distribution of Si, Fe, and Cu in FeSi 2 alloys, with or without the addition of Cu, were studied by electron probe microanalysis (EPMA). Alloys were prepared by slow solidification from the melt. Without Cu addition, both e-and a-phases were clearly observed, and a b-phase surrounding the e-phase was additionally observed after in situ annealing at 950°C for 12 h. With inclusion of 0.5 at.% Cu, the eutectoid reaction (a fi b + Si) was enhanced greatly. Only 0.01 at.% Cu was dissolved into the e-phase, with the excess Cu atoms being largely found at the outer edge of the e-phase. Ex situ annealing at 950°C for 12 h greatly changed the distribution of Si, Fe, and Cu. The e-phase changed its Si/Fe atomic ratio from 1.470 to 1.907, indicating an early stage of the peritectoid reaction (e + a fi b) and/or the subsequent reaction (e + Si fi b), with an increase in the Cu content up to 0.04 at.%. The size of this new phase was smaller than the original e-phase, and this new phase was surrounded by a shell of Si/Fe with an atomic ratio of 0.727 to 1.788 and a Cu content of 0.01 at.% to 0.11 at.%. In situ annealing under the same condition yielded different results: a large amount of Si segregates from the a-phase matrix, leaving a Si/Fe atomic ratio of only 0.506 to 0.530. The peritectoid reaction of the e-phase was found to depend on the Cu content. For the e-phase with undetectable levels of Cu, the Si/Fe atomic ratio remained at 0.954 to 0.998, but this ratio decreased with increasing Cu content to 0.55 at 2.20 at.% Cu. A plot of at.% Cu versus Si/Fe atomic ratio revealed a local minimum at the e-phase and expectedly at both the b-and a-phases. Nonstoichiometric structures (neither a-, b-nor e-phases) seemed to have higher at.% Cu compared with those with the closest Si/Fe composition.

Materials Science and …, 1992

A review of the literature reveals ternary phase diagram data for a number of systems involving MoSi 2. Although incomplete, this literature provides the initial basis for a rational approach to alloy design. For example, one can assess the high temperature stability of various artificially introduced reinforcements, such as niobium or SiC in an MoSi 2 matrix and the possibilities for the development of stable two-phase microstructures in quasibinary alloys in the MoSi2-TiSi 2 and MoSi2-TaSi 2 systems. Revised phase diagrams for these latter systems are presented that indicate the absence of the C 11 b-tO-C40 high temperature polymorphic transformation in pure MoSi 2.

Acta Materialia

The existence of the miscibility gap in the Cu-Ni system has been an issue in both computational and experimental discussions for half a century [Chakrabarti et al., Phase diagrams of binary nickel alloys, ASM, 1991]. Here we propose a new miscibility gap in the Cu-Ni system measured in nano-layered thin films by Secondary Neutral Mass Spectrometry. The maximum of the symmetrical miscibility curve is around 800 K at Cu 50% Ni 50% . To our best knowledge, this is the first experiment determining the miscibility from the measurement of the atomic fraction of Copper and Nickel in the whole composition range. Needless to say that Ni, Cu and its alloys are important in various fields, accordingly this result affects different areas to understand materials sciences.

Single crystal X-Ray Diffraction analysis (XRD) and Total reflection X-Ray Fluorescence (TXRF) analysis of the metallic phase -FeSi 2 reveals evidences of the existence of a new monoclinic P12/m1 deformation of the up to now reported tetragonal P4/mmm structure probably due to the existence of Fe and Si vacancies in the lattice of the studied material. The deformation is only due to the anisotropy of the atomic thermal vibrations, remaining the unit cell as tetragonal. The direct analysis of the diffraction intensities and the refinement by least squares give a fitted formula of Fe 0.86(1) Si 2.00(1). In parallel, the analysis by TXRF shows a stoichiometry of Fe 0.84(1) Si 2.00(2) , in agreement with the XRD results. The experimental measured density of 4.49(4) g/cm 3 also suggests the existence of Si vacancies. In this way, the new stoichiometry proposal for this phase is Fe 0.83(1) Si 1.92(2).

Journal of Alloys and Compounds, 1997

The mechanical alloying (MA) of Fe and Si powder with ball milling conditions LWI-espo ding to an injected shock power of 1.3 g '. leads to an expansion OS the A2 crystalline disor.kred solid solution phase region up to 27.5 at.96 Si (the ~~ui~i~~i~ Si). In this composition range, an amorphous phase is also detected. In the mrchittG~ally alloyed states, that for a Si content less than 15 at.%, the Fe and Si atoms a jmiy distributed according to it binon structure. For higher Si content. even the X-ray dit'l'r;lctiotI show thilt the rimdon distribution ot' the ;md Si ihlt~tllh in lhc crystirllitle lattice c;111 110 S.A. statistically distributed Ils. Their analysis I "Corresponding author. 'New adress: CNRS-LCMSTR-I Place aristide briand. 92195 Meudon cedex. France. 09258388/97/$17.0( 8 1997 Usevier Science S.A. All rights resmed. P/I SO925-8388(97)00102-3

Physica Status Solidi (a), 1988

Physikalisch-Technisches Institut, Jenal) (a) and Institut fur Festkorperphysik und Elektronennbikroskopie, Halle2) (b) der Akademie der Wissenschaften der DDR A Reinvestigation of Ni,Si Thin Film Growth on Si(ll1) by TEM and RBS Evidence of the Presence of an Interfacial Nisi Layer prior to Ni Consumption BY R. MATTIIEIS (a) and D. HESSE: (b) Dedicated t o Professor WILFRIED ANDRA on the occasion of his 65th birthday The formation of Ni,Si films on Si(11 1) substrates at temperatures below 700 K is investigated by transmission electron microscopy and Rutherford backscattering spectrometry. The structure and morphology of the growing Ni,Si phase are analysed. A thin, epitaxial, interfacial Nisi layer of constant thickness of about 15 nm is detected a t the Ni2Si/Si(lll) interface, which is probably present from the very beginning of Ni,Si growth. I t s structure and morphology are investigated, and its unexpected presence with respect t o the generally accepted phase formation sequence is discussed. Mit Hilfe der Transmissionselektronenmikroskopie und der Rutherford-Riickstreuspektrometrie wird die Bildung dunner Ni,Si-Schichten auf Si(ll1)-Substraten bei Temperaturen unter 700 K untersucht. Struktur und Morphologie der wachsenden Ni,Si-Phase werden analysiert. An der Ni,Si/Si(111)-Grenzfl&che wird eine diinne epitaxiale Nisi-Grenzschicht mit einer konstant bleibenden Dicke von ca. 15 nm gefunden, die wahrscheinlich vom Beginn des Ni,Si-Wachstuma a n vorhanden ist. Struktur und Morphologie dieser Grenzschicht werden untersucht, und es wird ihr im HinbIick auf die allgemein akzeptierte Phasenbildungsseqnenzunerwartetes Auftreten diskutiert.

Zeitschrift Fur Anorganische Und Allgemeine Chemie, 2010

The constitution of the ternary system Ni/Si/Ti is investigated over the entire composition range using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), differential thermal analysis (DTA), and metallography. The solid state phase equilibria are determined for 900 °C. Eight ternary phases are found to be stable. The crystal structures for the phases τ1NiSiTi, τ2Ni4Si7Ti4, τ3Ni40Si31Ti13, τ4Ni17Si7Ti6, and τ5Ni3SiTi2 are corroborated. For the remaining phases the compositions are determined as Ni6Si41Ti53 (τ6), Ni16Si42Ti42(τ7), and Ni12Si45Ti43 (τ8). The reaction scheme linking the solid state equilibria with the liquidus surface is amended to account for these newly observed phases. The discrepancies between previous experimental conclusions and modeling results are addressed. The liquidus surface is dominated by the primary crystallisation field of τ1NiSiTi, the only congruently melting phase.