Influence Of Gd Addition Research Articles

Influence of Gd Addition on the Microstructure and Superconducting Properties of YBCO Bulk Superconductors

Influence of Gd Addition on the Microstructure and Superconducting Properties of YBCO Bulk Superconductors

Phase separation in Zr56-xGdxCo28Al16 metallic glasses (0 ⩽ x ⩽ 20)

The influence of Gd addition on the microstructure of Zr56Co28Al16 metallic glasses was investigated for the exchange of Zr by up to 20 at.% Gd. Due to the large positive enthalpy of mixing between Zr and Gd, liquid–liquid phase separation occurs during rapid quenching of the melt. For a low concentration of Gd (x=2 at.%), a homogeneous amorphous structure is obtained for the as-quenched state. Early stages of spinodal decomposition are observed in the as-quenched state of the glasses with x=5 and 10 at.% Gd. Gd-enriched clusters 4–7nm in size are formed, as shown by atom probe tomography (APT). Annealing below the crystallization temperature Tx leads to an increase in the amplitude of compositional fluctuations and the analysis of the spatial atomic distribution by APT provides direct evidence of the spinodal character of the decomposition by uphill diffusion of Gd into the clusters. For higher Gd content (x=15 and 20 at.%), a coarsened microstructure of the phase-separated glass is obtained due to growth and coalescence while quenching the melt. The microstructure formation is essentially determined by the thermodynamic properties of the metastable undercooled liquid.

Influence of Gd Addition on the Structure and Capability of Ni-Mn-In Metamagnetic Shape Memory Alloys

The influences of Gd concentration on martensitic transformation and magnetic properties of NiMnIn alloys were investigated by differential scanning calorimetry (DSC) , vibrating sample magnetometry (VSM), X-ray diffraction (XRD) and etc. It is Observed through the experiment: the addition of Gd enhances martensite transition temperature;X-ray diffraction analysis of experimental alloys is revealed that to the mixture is martensite and austenite at room temperature; content of Gd is not proportional to the improvement of magnetic property.

Phase separation in Cu 46Zr 47− xAl 7Gd x metallic glasses

The influence of Gd addition on phase separation of rapidly quenched Cu 46Zr 47− x Al 7Gd x metallic glasses ( x = 2,5,7) was studied. For low Gd content ( x = 2), a homogeneous glass is obtained for the as-quenched state. Annealing leads to cluster formation by nucleation and growth prior to crystallization. For the Gd contents x = 5 and 7, early stages of spinodal decomposition are observed in the as-quenched glasses. Further annealing increases the amplitude of the compositional fluctuations prior to crystallization. Atom probe tomography gives evidence of the presence of Gd-enriched clusters of 2–5 nm size for the Cu 46Zr 42Al 7Gd 5 glass. The structure formation as a function of the Gd content is essentially determined by the composition dependence of the miscibility gap of the metastable undercooled melt. Early stages of spinodal decomposition or almost homogeneous glassy states are obtained if the critical temperature of liquid–liquid phase separation is close or below to the glass transition temperature.

The influence of Gd addition on microstructure and transport properties of Bi-2223

We have investigated the effect of addition of Gd in Bi 1.8Pb 0.35Sr 1.9Ca 2.1Cu 3Gd x O y superconductor with x=0, 0.1, 0.2, 0.3, 0.4 and 0.5. The samples were prepared by standard solid-state reaction methods. The investigation consisted of X-ray diffraction (XRD), scanning electron microscopy (SEM), dc electrical resistivity, hole concentration and transport critical current density measurements. Transport measurements indicated that the superconducting transition temperature, transport critical current density and hole concentration values of the samples strongly depend on the Gd addition. The values of T c, and J c of the samples decreased with the increase in Gd addition. When Gd addition ratio was increased, surface morphology and grain connectivity of the samples were observed to degrade from SEM investigations and phase ratio of the high- T c (Bi-2223) phase to the low- T c (Bi-2212) phase decreased (XRD measurements). The possible reasons for the observed degradation in superconducting and microstructure properties of Bi-2223 due to Gd addition were discussed.

Influence of gd addition on the structure and properties of Au-Ni and Au−Ni−Cr alloys

The influence of Gd additions on the microstructure and properties of Au-Ni and Au-Ni-Cr alloys are reported. The alloys remain single phase solid solution at Gd contents of −0.1wt%, but at contents τ 0.1%, two phases structures are formed, consisting of (Au) and a low melting point intermetallic compound containing Gd. Trace additions of Gd refine the grain size, increase strength and the recrystallization temperature, but without detriment to the good electric conductivity of these alloys. The wear life of potentiometer windings made of gold alloys containing Gd are at least one order of magnitude higher than those made in the Gd-free gold alloys. The design of gold alloys for precise electrical contact and resistance materials by conventional and microalloying is discussed.

Influence of Gd addition on the magnetism and structure of Finemet-type nanocrystalline alloys

Influence of Gd addition on the magnetism and structure of Finemet-type nanocrystalline alloys

Influence of Gd addition on the magnetism and structure of Finemet-type nanocrystalline alloys

Abstract The effect of rare earth addition in the structure and magnetism of melt spun nanocrystalline Finemet-type alloys devitrified from amorphous precursor ribbons is discussed. Starting with the initial composition Fe73.5Cu1Nb3Si13.5B9 an amount of 5 at% Gd is introduced into the primary alloy. The purpose is to enable after appropriate recrystallization the occurrence of hard and soft magnetic, suitably dispersed, exchange-coupled nanograins and to determine the transformation sequences of the crystallization process and the obtained crystallization products.

Development of Gd-Enriched Alloys for Spent Nuclear Fuel Applications - Part 1: Preliminary Characterization of Small Scale Gd-Enriched Stainless Steels

The influence of Gd additions on the microstructure and hardness of type 316L stainless steel was investigated by various microstructural characterization techniques. This work was conducted as a first step toward the development of Gd-enriched alloys for spent nuclear fuel applications. Small (∼10 g) gas tungsten arc melt buttons were prepared to produce 316L stainless steel with Gd levels from 0.1–10 wt.% Gd. Electron microprobe measurements showed that Gd is essentially insoluble in the austenite/ferrite matrix. All of the alloys formed an interdendritic (Fe, Ni, Cr)3Gd intermetallic, and the amount of the (Fe, Ni, Cr)3Gd phase increased with increasing Gd concentration. Depending on the P and O levels, various amounts of Gd phosphides and oxides were also observed. The relatively high Ni concentration (∼28 wt.% Ni) and low Cr concentration (∼3 wt.% Cr) of the (Fe, Ni, Cr)3Gd phase led to Ni depletion and Cr enrichment in the matrix which, in turn, affected the matrix stability. Alloys with 0.1−6 wt.% Gd exhibited a two-phase ferrite/austenite matrix. Alloys containing 8 and 10 wt.% Gd exhibited a fully ferritic matrix due to extensive Ni depletion/Cr enrichment and concomitant stabilization of ferrite. Hardness increased with increasing Gd concentration due to the formation of the (Fe, Ni, Cr)3Gd intermetallic and the change in matrix structure from austenite to ferrite. A mass balance procedure is presented that accounts for changes to the matrix composition with Gd concentration. This procedure can be used to determine the nominal alloy composition required to produce a 316L-type matrix composition for any Gd level.

Influence of Gd addition on the magnetic properties of Fe-Cu-Nb-Si-B ribbons

The magnetic properties of the amorphous and nanocrystallized Fe-Cu-Nb-Si-B and Fe-Gd-Cu- Nb-Si-B ribbons are studied using temperature dependence of the specific magnetization. A two-phase ferromagnetic behaviour is obtained for the magnetization curves. Gd addition tends to stabilize the interfacial (grain boundary) phase by forming a metastable Gd-Fe-B phase, leading to the coexistence of two phases up to thermal treatments as high as 993K.

Structural properties of amorphous and nanocrystallized FeCuNbSiB and FeGdCuNbSiB ribbons

The influence of Gd addition on the structural properties of FeCuNbSiB nanocrystallized and amorphous alloys is studied. The crystallization temperature increases and the microstructure of the annealed samples changes. Gd addition induces the formation of GdFeB phases. In fully crystallized FeGdCuNbSiB alloys the α-Fe(Si), FeNbB, Gd 3Fe 62B 14 and Gd 1.1Fe 4B 4 phases are observed. The evolution of the microstructure is followed as a function of the cumulative effects of annealing time and temperature. The results suggest the transformation of the metastable Gd 3Fe 62B 14 phase into Gd 1.1Fe 4B 4 and α-Fe. The hyperfine parameters of the Gd 3Fe 62B 14 Mössbauer contribution are reported.