Glass-Forming Ability and Crystallization of High Purity Pd-Cu-Ni-P Alloy

2000 ◽  
Vol 644 ◽  
Author(s):  
Nobuyuki Nishiyama ◽  
Mitsuhide Matsushita ◽  
Akihisa Inoue
Keyword(s):  
High Purity ◽  
Isothermal Annealing ◽  
Glass Forming Ability ◽  
In Situ Tem ◽  
Nucleation Behavior ◽  
Spherical Region ◽  
Glass Forming ◽  
High Purity Alloy ◽  
Nose Temperature

AbstractGlass-forming ability, thermal stability and nucleation behavior of a Pd40Cu30Ni10P20 alloy prepared using a high purity polycrystalline phosphorus are investigated. The critical cooling rate for glass formation for the high purity alloy is the same as that for the previous result, but the improvement of undercooling reaches about 80 K as compared with the fluxed ordinary alloy. In comparison with the non-fluxed alloy, the solidified structure of the present highly purified alloy is significantly different. The non-fluxed sample shows the characteristic “island-like” structure consisted of acicular fcc-Pd2Ni2P solid solution and Cu3Pd intermetallic compound. These acicular phases appear to be caused by the growth of quenched-in nuclei. In the isothermal experiment, nucleus density exhibits time dependence even at 683 K near the nose temperature. It is assumed that the crystallization behavior for the highly purified alloy is closer to homogeneous nucleation from quenched-in nuclei dominant behavior. In order to investigate the nucleation behavior, in-situ TEM observation was carried out. Spherical Pd15P2 particle with a diameter about 15 nm is observed, and this spherical region repeats generation and annihilation during isothermal annealing. The reason for the high glass-forming ability is discussed on the basis of the obtained results.

scholarly journals In situ TEM thermal annealing of high purity Fe10wt%Cr alloy thin foils implanted with Ti and O ions

2019 ◽  
Vol 461 ◽  
pp. 219-225
Author(s):  
Martin Owusu-Mensah ◽  
Stéphanie Jublot-Leclerc ◽  
Aurélie Gentils ◽  
Cédric Baumier ◽  
Joël Ribis ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
High Purity ◽  
In Situ Tem ◽  
Thin Foils

In-Situ TEM Deformation Studies of Dislocation Generation and Motion in High-Purity MO Single Crystals

1999 ◽  
Vol 578 ◽  
Author(s):  
M. Jouiad ◽  
B. W. Lagow ◽  
I. M. Robertson ◽  
D. H. Lassila
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
High Purity ◽  
In Situ Tem ◽  
Dislocation Source ◽  
Dislocation Generation ◽  
Transmission Electron ◽  
Dislocation Tangle ◽  
Source Operation

AbstractThe generation and motion of dislocations in high-purity single crystals of Mo have been observed in real time by deforming electron-transparent samples in-situ in a transmission electron microscope. At 300 K and at low levels of stress, a novel dislocation source was observed that generated a long, straight screw dislocation. The source was a dislocation tangle that existed in the annealed material. An edge dislocation emerged from the tangle, trailing behind it the screw dislocation. These screw dislocations were immobile at this stress level. At higher stresses, the same dislocation tangle generated many dislocations, but now by a pole mechanism. The nature of these tangles and the source operation mechanisms will be described.

TEM Studies of Shear Bands in a Bulk Metallic Glass Based Composite

2001 ◽  
Vol 7 (S2) ◽  
pp. 1120-1121
Author(s):  
E. Pekarskaya ◽  
C.P. Kim ◽  
W.L. Johnson
Keyword(s):  
Metallic Glasses ◽  
Shear Bands ◽  
High Yield ◽  
In Situ Tem ◽  
Two Phase ◽  
University Of Illinois ◽  
Glass Forming ◽  
The University ◽  
Very High

In 1980’s the discovery of multicomponent systems with exceptional glass forming ability enabled the synthesis of metallic glasses at relatively low cooling rates, 10−1 — 102 K/s and at a larger thicknesses. Bulk metallic glasses normally have very high yield stress, σy = 0.02 · Y (Y is Young’s modulus), high elastic limit of about 2%, but fail with very little global plasticity, typically along a localized shear band at a 45 degree angle with respect to the applied stress.The material studied in the present work is a two-phase Zr56.3Ti13.8Cu6.9Ni5.6Nb5.0Be12.5 alloy,prepared by in-situ processing. The alloy consists of amorphous and crystalline phases. In-situ TEM straining (tensile) experiments were performed at room temperature in JEOL 4000EX operating at 300kV. The experiments were carried out in the Center for Microanalysis of Materials in the University of Illinois at Urbana-Champaign. The goal of the study was to understand the deformation mechanisms of such composite material.

Deformation-Induced Nanocrystallization in Al-Rich Metallic Glasses

2006 ◽  
Vol 114 ◽  
pp. 123-132 ◽  
Author(s):  
Nancy Boucharat ◽  
Rainer J. Hebert ◽  
Harald Rösner ◽  
Gerhard Wilde
Keyword(s):  
Metallic Glasses ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
In Situ Tem ◽  
Number Density ◽  
High Number Density ◽  
Glass Forming ◽  
Processing Strategies ◽  
Improved Performance

Deformation-induced nanocrystallization has been investigated in a marginally Al88Y7Fe5 glass forming alloy. Conventional calorimetry and microstructural analyses of materials that have been subjected to high pressure torsion straining (HPT) at room temperature indicate the development of an extremely high number density of small Al nanocrystals. The nanocrystals appear to be distributed homogeneously throughout the sample without any evidence of strong coarsening. Moreover, the comparison between nanocrystallization caused by the application of either HPT, cold-rolling or in-situ TEM tensile straining yielded the identification of the probable mechanisms underlying the formation of nanocrystals. These results form the basis for the development of advanced processing strategies for producing new nanostructures with high nanocrystal number densities which allow increased stability and improved performance.

Glass Forming Ability and Thermal Properties of a Cu-Based Bulk Metallic Glass Microalloyed with Silicon

2007 ◽  
Vol 561-565 ◽  
pp. 1341-1344 ◽  
Author(s):  
Jason S.C. Jang ◽  
Y.C. Huang ◽  
C.H. Lee ◽  
I.S. Lee ◽  
L.J. Chang
Keyword(s):  
Activation Energy ◽  
Thermal Properties ◽  
Isothermal Annealing ◽  
Alloy System ◽  
Glass Forming Ability ◽  
Casting Method ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Glass Forming ◽  
Activation Energy Of Crystallization

The (Cu42Zr42Al8Ag8)100-xSix amorphous alloy rods, x =0 to 1, with 3 mm in diameter were prepared by Cu-mold drop casting method. The glass forming ability, thermal properties and microstructure evolution was studied by differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). The XRD result reveals that these as-quenched (Cu42Zr42Al8Ag8)100-xSix alloy rods exhibit a broaden diffraction pattern of amorphous phase. The crystallization temperature and GFA (glass forming ability) of (Cu42Zr42Al8Ag8)100-xSix alloys increase with the silicon additions. The highest Trg (0.59) and γ value (0.405) occurred at the (Cu42Zr42Al8Ag8)99.75Si0.25 and (Cu42Zr42Al8Ag8)99.5Si0.5 alloy. In addition, both of the activation energy of crystallization and the incubation time of isothermal annealing for these (Cu42Zr42Al8Ag8)100-xSix alloys indicates that the (Cu42Zr42Al8Ag8)99.25Si0.75 alloy posses the best thermal stability among the (Cu42Zr42Al8Ag8)100-xSix alloy system.

In situ TEM observation of tensile deformation in high-purity titanium after a single compression stroke

1989 ◽  
Vol 23 (4) ◽  
pp. 553-556 ◽  
Author(s):  
Zhang Jieping ◽  
Gu Haicheng ◽  
Zhou Huiju ◽  
Campbell Laird
Keyword(s):  
High Purity ◽  
Tensile Deformation ◽  
In Situ Tem ◽  
Compression Stroke ◽  
Purity Titanium

Zr-Cu-Ni-Al-Ta glassy matrix composites with enhanced plasticity

2006 ◽  
Vol 21 (6) ◽  
pp. 1490-1499 ◽  
Author(s):  
Wenbo Dong ◽  
Haifeng Zhang ◽  
Wensheng Sun ◽  
Aimin Wang ◽  
Hong Li ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Volume Fraction ◽  
Shear Bands ◽  
Glass Forming Ability ◽  
Glassy Matrix ◽  
Matrix Composites ◽  
Glass Forming ◽  
Mould Casting ◽  
Copper Mould

(Zr62Cu15.4Ni12.6) (x = 6–12) in situ glassy composites containing uniformly distributed Ta-rich particles were prepared by arc-melting and copper mould casting. The results show that addition of 6–10 at.% Ta to Zr62Cu15.4Ni12.6Al10 results in dissolution of 2.4 to 4.6 at.% Ta in the glassy matrix, which promotes glass-forming ability, and the remaining Ta precipitates out as body-centered cubic (BCC) Ta-rich particles dispersed on the glassy matrix. The critical diameters for the composites with 6, 8, and 10 at.% Ta are 7, 7, and 6 mm, respectively. At 12 at.% Ta addition, the glass-forming ability is dramatically reduced because of the precipitation of secondary dendritic Ta-rich particles and other nanocrystallites from melts during copper mould casting. Also, owing to the solid-liquid reaction during induction heating, some Ta-rich particles formed in the master alloys will redissolve into the glassy matrix, resulting in a smaller volume fraction of Ta-rich particles in the as-cast glassy rods than that of the corresponding ingots. The glassy matrix composites exhibit enhanced plastic strain of about 7.5 to 22.5% at room temperature. The optimum Ta content in the glassy alloys is determined to be 10 at.%, which corresponds to the highest ultimate stress of 2220 MPa and the largest plastic strain of 22.5%. The plastic strain increases with increasing volume fraction of in situ BCC Ta-rich particles. This is apparently ascribed to the impedance of Ta-rich particles to shear bands. Ta-rich particles seed the initiation of multiple shear bands and block the shear band propagation, leading to intensive multiplication and bifurcation of shear bands.

In situ TEM studies of irradiation effects for materials improvement

1991 ◽  
Vol 49 ◽  
pp. 452-453
Author(s):  
Charles W. Allen
Keyword(s):  
Nuclear Reactor ◽  
Austenitic Stainless Steels ◽  
High Energy ◽  
Point Of View ◽  
In Situ Tem ◽  
Irradiation Effects ◽  
Tem Analysis ◽  
Radiation Induced ◽  
Analytical Tools

Irradiation effects studies employing TEMs as analytical tools have been conducted for almost as many years as materials people have done TEM, motivated largely by materials needs for nuclear reactor development. Such studies have focussed on the behavior both of nuclear fuels and of materials for other reactor components which are subjected to radiation-induced degradation. Especially in the 1950s and 60s, post-irradiation TEM analysis may have been coupled to in situ (in reactor or in pile) experiments (e.g., irradiation-induced creep experiments of austenitic stainless steels). Although necessary from a technological point of view, such experiments are difficult to instrument (measure strain dynamically, e.g.) and control (temperature, e.g.) and require months or even years to perform in a nuclear reactor or in a spallation neutron source. Consequently, methods were sought for simulation of neutroninduced radiation damage of materials, the simulations employing other forms of radiation; in the case of metals and alloys, high energy electrons and high energy ions.

Sign in / Sign up

Export Citation Format

Share Document