GlidCop Al-15 Research Articles

Material Plasma Exposure eXperiment High Heat Flux Microwave Absorber Design, Manufacture, and Articles Test

The Material Plasma Exposure eXperiment (MPEX) at Oak Ridge National Laboratory is in the final design phase. MPEX will be capable of exposing neutron-irradiated materials to plasmas for the study of plasma-material interaction. This facility will provide information about the complex effects of plasmas on materials and contribute to examining new materials that can withstand high heat fluxes and high ion fluences for future fusion devices. MPEX plasma is heated by 70-GHz or 105-GHz electron Bernstein wave/electron cyclotron heating (ECH), and the high-frequency microwaves are prone to scattering microwave power, which can have detrimental effects, especially on diagnostic components. A large portion of the injected ECH power is expected to be absorbed by plasma, but the remainder requires that microwave absorbers be placed immediately upstream and downstream of the ECH launcher to minimize stray microwaves leaving the ECH region. These microwaves can inadvertently heat components that cannot be shielded or otherwise protected. The microwave absorber design is based on an array of pyramid-shaped ceramic tiles brazed to a water-cooled explosion-bonded heat sink and a stainless steel plate to produce one tile module. Computational fluid dynamics and structural analyses were performed to optimize and validate the design. Multiple test coupons were produced to validate the process for brazing the two different tile materials to the Glidcop AL-15 baseplate. The articles were tested to evaluate the reliability and thermal performance through exposure to an electron beam with a heat flux of up to 1.5 MW/m2. Nondestructive testing was performed before and after testing to identify voids or separations that may have been introduced by the high heat flux. This paper discusses the details of high heat flux microwave absorber design, manufacturing details and associated challenges, and test results, demonstrating the effectiveness of the proposed design.

Material Plasma Exposure eXperiment (MPEX) High Heat Flux Bellows for Component Alignment in High Microwave Environment

The Material Plasma Exposure eXperiment (MPEX) device is a linear plasma device developed to perform plasma material interaction experiments under the conditions prototypic of a fusion reactor divertor. MPEX has multiple systems that must be precisely aligned to the plasma axis, including an electron cyclotron heating system that emits up to 400 kW of microwave power into the vacuum vessel. Five distinct systems require precise alignment on the MPEX device, thus requiring four bellows, all of which are adjacent to the plasma at a relatively high heat flux of approximately 47 kW/m2 and microwave power regions. The MPEX high heat flux bellows (HHFB) is designed to deliver 6 degrees of freedom positioning. The HHFB includes titanium–zirconium–molybdenum (TZM) inserts that are brazed into a Glidcop AL-15 body using a high-temperature braze alloy, thus blocking direct line of sight to an edge-welded bellows from the plasma and microwave screen to block microwaves from the bellows. A custom ConFlat knife edge is machined into the Glidcop AL-15, so the vacuum flanges do not need a braze or weld joint on the vacuum interface. Fingerstock or copper mesh is used to restrict microwave power from entering the interstitial space between the water-cooled Glidcop AL-15 body and edge-welded bellows. Glidcop AL-15 was selected as the material of choice for the water-cooled body because it can maintain mechanical integrity at elevated temperatures, and it also allows for a high-temperature braze. TZM was selected for its machinability and compatibility with vacuum and plasma requirements. A test article is also being considered for a similarly shaped component, the MPEX limiter, that will demonstrate the integrity of the braze joint under high thermal load. Results from this testing will be extrapolated to deduce the lifetime and integrity of the HHFB design.

MPEX High Heat Flux Plasma Dump Design, Manufacture, and Articles Test

The Material Plasma Exposure eXperiment (MPEX) device is a steady-state linear plasma device currently in the final design phase at the Oak Ridge National Laboratory. This device will reach ion fluences up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{31}\,\,\text{m}^{-2}$ </tex-math></inline-formula> and will be used to expose neutron-irradiated materials to divertor-relevant plasmas and to study the effects of plasma-material interactions. These studies will elucidate the complex effects of plasmas with divertor candidate materials capable of withstanding high heat flux and high fluences for next-generation fusion devices. Bidirectional plasma will be generated using a high-power (200 kW) helicon source. Plasma will be confined by superconducting magnets. The last plasma-facing component on the upstream side of the MPEX device is the dump, which has been designed to intercept plasma and energetic particles. The dump will have a total heat load of 9.2 kW. A copper alloy (Glidcop AL-15) was selected for use in the water-cooled flange design because of its high thermal conductivity, its retaining strength at elevated temperatures, and its ability to be used in the high-temperature braze joints used in this application. Titanium-zirconium-molybdenum (TZM) tiles are brazed to the Glidcop AL-15 flange using high-temperature braze alloy. External water-cooling channels are used on the dump flange to prevent water leakage inside the vacuum space. This article discusses the details of the high heat flux dump design, including the computational fluid dynamics (CFD) and structural analyses performed to validate the design to meet the operational requirements of the MPEX device.

Copper-based alloys for structural high-heat-flux applications: a review of development, properties, and performance of Cu-rich Cu–Cr–Nb alloys

ABSTRACT This review examines the development and current state of Cu-rich Cu–Cr–Nb alloys commonly referred to as GRCop or Glenn Research copper alloys with emphasis on Cu–8Cr–4Nb (at%), or GRCop-84, and Cu–4Cr–2Nb, or GRCop-42. Recent additive manufacturing efforts have increased interest in GRCop alloys, and full-scale hardware has been fabricated using AM techniques and practical hot-fire tests have been conducted, but structure–property relationships are still under development. The development, processing, and current microstructure-property relationships of GRCop alloys are reviewed along with comparisons to similar high-heat-flux Cu alloys including NARloy-Z, GlidCop Al-15, AMZIRC, Cu–1Cr–0.1Zr, and Cu–0.9Cr. The review concludes with an assessment of future prospects for GRCop alloys and overview of advantages provided by additive manufacturing.

An improved description of creep in dispersion-strengthened metals

An improved model based on thermally activated dislocation glide is proposed to describe the dislocation detachment-controlled creep of extruded and annealed GlidCop Al-15 and extruded GlidCop Al-60 at 973 K as well as the threshold behavior observed at lower stresses. Unlike the customary analysis using the Rösler-Arzt approach, both steady-state and strain-transient stress reduction creep tests were performed to obtain the activation energies and the obstacle strengths for creep. In contrast to pure copper, the constant-structure creep rates of GlidCop were greater than the subsequent steady-state creep rates in all tests. This result supports the concept that dislocation detachment from particles, rather than dislocation-dislocation interactions, is rate-controlling. In addition, the constant-structure creep rates at the same reduced stresses were found to be greater at higher initial stresses. This observation is interpreted as evidence that a forward internal stress arising from inter-dislocation interactions near the particles acts on the ready-to-detach dislocations and scales with the initial stress. This forward stress and an explicit treatment of the stress dependence of mobile dislocation density were incorporated in the improved model. Furthermore, the operational activation area for dislocation glide was determined at constant temperature and structure, and the values are consistent with the interparticle distances multiplied by the Burgers vector, which further supports the interpretation of detachment controlled glide. Finally, the true threshold stress for creep is modeled as originating from thermodynamic back jumps of just-detached dislocations due to the attractive nature of the particle/matrix interface.

Influence of annealing on the creep behavior of GlidCop Al-15

The steady-state creep behavior of annealed GlidCop Al-15 (100 h, 1273 K) was studied at 973 K and compared to the extruded version. The Rösler-Arzt model applies well to both extruded and annealed alloys, suggesting the major deformation mechanism to be dislocation detachment from particles. However, threshold behavior was also observed at low stresses for both material conditions, which can be phenomenologically described by the threshold stress model. The annealed GlidCop samples exhibited better creep resistance than their extruded counterparts, the reason behind which was carefully examined in terms of the annealing effects on grain size, texture, dislocation density, and particle size and distribution. This investigation reveals that none of the above are the primary factors affecting the difference in the creep behavior of the two forms of GlidCop. Instead, the transformation of Al2O3 particles to 9Al2O3–B2O3 after long-term annealing is considered to be the major cause of the difference in steady-state creep rates, as the resulting less-coherent particle/matrix interface increases the energy required for the dislocation detachment process.

200 MeV proton irradiation of the oxide-dispersion-strengthened copper alloy (GlidCop-Al15)

In search to identify extremely stable materials to perform the collimation function of the 7-TeV proton beam halo at the Large Hadron Collider (LHC), oxide dispersion strengthened (DS) copper alloys were explored. These internally oxidized copper alloys known as GlidCop are also leading candidates for high heat flux applications in fusion reactors and as divertor and first wall structure in ITER. These considerations have led to an extensive body of research on neutron-induced changes in the microstructure and physio-mechanical properties. This study focused primarily on the damage induced by 200 MeV protons on as wrought and cold-worked GlidCop Al15 DS copper ally selected as a candidate material of the LHC beam collimation structure to damage levels up to ∼10 displacements-per-atom (dpa) and irradiation temperatures up to ∼600 °C. For reference, low dose spallation neutron damage at sub-zero irradiation temperature was included in the study. Proton irradiation effects on dimensional stability, mechanical behavior, electrical resistivity and X-ray diffraction-based microstructural changes are presented in the paper. GlidCop Al15 exhibited excellent thermal stability and superior to pure Cu resistance to conductivity loss. Proton irradiation-induced hardening and embrittlement at distinct irradiation temperature regimes were shown to follow similar trends to what was reported under neutron exposure to even higher dpa damage. At Tirr ∼600 ± 20 °C the cold-worked DS copper alloy exhibited softening accompanied by elongation reduction while at Tirr ∼200 ± 10 °C the as-wrought experienced hardening with elongation increase. High resolution X-ray diffraction revealed that even low-dose neutron irradiation has a strong influence on the size and distribution of dispersed Al2O3 particles.

An Experimental Study for Low-Cycle Fatigue Crack Propagation of Glidcop Al-15

Experiments have been conducted on an oxide dispersion strengthened (ODS) copper Glidcop Al-15 under a range of cyclic stress-amplitudes at room temperature. Special specimens containing an artificial small hole of various diameters, i.e. 150, 200 and 300 μm, were used. Propagation process of surface cracks in the various holed specimens was recorded to investigate the fatigue crack growth rate. Scanning electron microscope (SEM) was used for the observation of the fracture surface after failure specimens. The well-known Coffin-Manson low-cycle fatigue relationship was substantially shown through the results. An equation between the growth rate of the surface crack and the stress amplitude for Gidcop Al-15 was carried out. The experiment proved that prior fatigue history makes little influence on the subsequent crack propagation property under low-cycle condition.

Mechanical Behavior of Glidcop Al-15 at High Temperature and Strain Rate

Strain rate and temperature are variables of fundamental importance for the definition of the mechanical behavior of materials. In some elastic-plastic models, the effects, coming from these two quantities, are considered to act independently. This approach should, in some cases, allow to greatly simplify the experimental phase correlated to the parameter identification of the material model. Nevertheless, in several applications, the material is subjected to dynamic load at very high temperature, as, for example, in case of machining operation or high energy deposition on metals. In these cases, to consider the effect of strain rate and temperature decoupled could not be acceptable. In this perspective, in this work, a methodology for testing materials varying both strain rate and temperature was described and applied for the mechanical characterization of Glidcop Al-15, a copper-based composite reinforced with alumina dispersion, often used in nuclear applications. The tests at high strain rate were performed using the Hopkinson Bar setup for the direct tensile tests. The heating of the specimen was performed using an induction coil system and the temperature was controlled on the basis of signals from thermocouples directly welded on the specimen surface. Varying the strain rate, Glidcop Al-15 shows a moderate strain-rate sensitivity at room temperature, while it considerably increases at high temperature: material thermal softening and strain-rate hardening are strongly coupled. The experimental data were fitted using a modified formulation of the Zerilli-Armstrong model able to reproduce this kind of behavior with a good level of accuracy.

Fatigue Life Prediction Strategies for High-Heat-Load Components

High-heat-load components such as photon shutters and masks made of Glidcop Al-15 are subjected to intense thermal cycles from the X-ray beams at the third generation light sources. This paper presents thermal fatigue life prediction results of high-heat-load components at the beam line front end of Shanghai Synchrotron Radiation Facility (SSRF) under different power conditions. Used in this analysis are four typical multiaxial fatigue life prediction models, i.e. the maximum principal strain model, equivalent vonMises strain model, maximum shear strain model and critical plane approach. Detailed comparisons among them were implemented from various aspects including applicable conditions, physical meanings and resultant veracities. Critical plane approach was finally determined to be more appropriate method for dealing with multiaxial fatigue of high-heat-load components. To obtain the multiaxial stress-strain fields, nonlinear finite element analysis (FEA) was performed with commercial software ANSYS.

Effect of temperature on the low cycle fatigue behavior of Glidcop Al-15

Glidcop Al-15 is an Oxide Dispersion Strengthened (ODS) copper which has been widely used throughout the world in high-heat-loaded components because of its high strength especially at higher temperatures. At the European Synchrotron Research Facility (ESRF, Grenoble, France) the Glidcop Al-15 is used for manufacturing photon absorbers. It consists in two segments of OFHC (Oxygen-Free High Conductivity) copper brazed with another segment of Glidcop Al-15. This absorber is subjected to intense thermal stress cycles due to the high intensity X-ray beams.This work aims at studying the fatigue behavior of the Glidcop Al-15 at high temperature (300 °C). This study is divided into two parts: First the effect of heat treatment cycles which simulate brazing operation on Glidcop Al-15 will be analyzed. Then the effect of temperature on low cycle fatigue (LCF) behavior and failure mechanisms will be discussed.

Comparison of GRCop-84 to Other Cu Alloys with High Thermal Conductivities

The mechanical properties of six highly conductive copper alloys, GRCop-84, AMZIRC, GlidCop Al-15, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z were compared. Tests were done on as-received hard drawn material, and after a heat treatment designed to simulate a brazing operation at 935 °C. In the as-received condition AMZIRC, GlidCop Al-15, Cu-1Cr-0.1Zr, and Cu-0.9Cr had excellent strengths at temperatures below 500 °C. However, the brazing heat treatment substantially decreased the mechanical properties of AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z. The properties of GlidCop Al-15 and GRCop-84 were not significantly affected by the heat treatment. Thus there appear to be advantages to GRCop-84 over AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z if use or processing temperatures greater than 500 °C are expected. Ductility was the lowest in GlidCop Al-15 and Cu-0.9Cr; reduction in area was particularly low in GlidCop Al-15 above 500 °C, and as-received Cu-0.9Cr was brittle between 500 and 650 °C. Tensile creep tests were done at 500 and 650 °C; the creep properties of GRCop-84 were superior to those of brazed AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z. In the brazed condition, GRCop-84 was superior to the other alloys due to its greater strength and creep resistance (compared to AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z) and ductility (compared to GlidCop Al-15).

The Oxidation Behavior of an ODS Copper Alloy Cu?Al2O3

The oxidation behavior of Glidcop AL-15 (Cu-O.3 wt.% Al2O3), an ODS copper alloy of interest for aerospace structural application, was investigated by oxidation and two-step oxidation in a TGA. The results were compared with the oxidation kinetics of pure Cu and two other aerospace Cu alloys, GRCop-84 (Cu-8Cr-4Nb) and NARloy-Z (Cu-3Ag-O.5Zr). AL-15 exhibited the lowest oxidation rate from 500 to 650°C. The superiority in oxidation resistance is thought to result from the Al2O3, and the two-step oxidation results suggest the Al2O3 dissolves in the oxide scale, perhaps creating charge and stress fields that suppress oxidation by retarding the Cu diffusion rate.

Development and applications of rectangular box-type explosively bonded structures for high-heat-load beamline components

Explosive bonding technology is a good choice to join dissimilar materials, such as 304L stainless steel and GlidCop AL-15, and is used extensively in making the advanced photon source (APS) high-heat-load beamline and front-end components. It is a bonding method in which the controlled energy of a detonating explosive is used to create a metallurgical bond between two or more similar or dissimilar materials. In recent years, special explosive bonding units with rectangular box-type joints were developed for the APS new high-heat-load beamline components. Based on this new technique, the box form of the component could be built in two halves first, then welded together. Therefore, beamline designers have more freedom to optimize the cooling surface geometry.

Properties of copper-silver and dispersion strengthened copper

The tensile and fatigue properties of cold-worked copper and a commercial Cu-Al2O3 dispersion-strengthened alloy were measured at temperatures between 25 and 600°C. The GLIDCOP Al-15 alloy, which contains 0.15 wt% Al in the form of Al2O3 particles, exhibited a significantly higher tensile and fatigue strength than copper under all test conditions. The mechanical properties of this alloy appear to be suitable for high-strength, high-conductivity alloy applications in fusion reactors.

GLIDCOP AL-60

Abstract GlidCop AL-60 is copper strengthened by adding a second phase (aluminum oxide) to the matrix by internal oxidation. The process produces a product with resistance to thermal softening, high strength, and creep resistance, combined with high electrical and thermal conductivity. (See also GlidCop AL-15, Alloy Digest Cu-603, May 1996, and GlidCop AL-25, Alloy Digest Cu-604, June 1996.) This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming and joining. Filing Code: CU-608. Producer or source: SCM Metal Products Inc.

GLIDCOP AL-25

Abstract GlidCop AL-25 is copper strengthened by adding a second phase (aluminum oxide) to the matrix by internal oxidation. The process produces a product with resistance to thermal softening, high strength, and creep resistance, combined with high electrical and thermal conductivity. (See also GlidCop AL-15, Alloy Digest Cu-603, May 1996, and GlidCop AL-60, Alloy Digest Cu-608, August 1996.) This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming and joining. Filing Code: CU-604. Producer or source: SCM Metal Products Inc.

Creep Deformation of Dispersion-Strengthened Copper

The creep behavior of an internally oxidized, A12O3 dispersion-strengthened copper alloy, GlidCop Al-15, has been investigated in the temperature range of 745 to 994 K. The results exhibit a high apparent stress exponent (10 to 21) and a high apparent activation energy for creep (253.3 kJ/mole). To describe the creep behavior of this alloy, the Rosler-Arzt model for attractive particle/dislocation interaction is applied. The results are in good agreement with the model when account is taken of the effects of the fine elongated grains and heavily dislocated structures revealed through transmission electron microscopy. The analysis demonstrates that the dislocation/particle interaction is of moderate strength in this alloy, consistent with the observation that the particle/matrix interface is partially coherent. In addition, the analysis reveals that the choice of mechanism and corresponding activation energy for vacancy diffusion has only a small effect on the calculated model parameters. It is argued that the weak dependence of subgrain size on stress demonstrates that creep deformation is particle controlled, rather than subgrain size controlled. In addition, the poorly developed subgrain structure and high dislocation densities are attributed to the presence of the fine oxide particles. Finally, the dependence of rupture time on stress is shown to be consistent with a description of creep fracture based on diffusive cavity growth with continuous nucleation.

GLIDCOP AL-15

Abstract GlidCop AL-15 is copper strengthened by adding a second phase, aluminum oxide, to the matrix by internal oxidation. The process produces a product with resistance to thermal softening, high strength, and creep, combined with high electrical and thermal conductivity. (See also GlidCop AL-25, Alloy Digest Cu-604, June 1996, and GlidCop AL-60, Alloy Digest Cu-608, August 1996.) This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming and joining. Filing Code: CU-603. Producer or source: SCM Metal Products Inc.

Low-Cycle fatigue of dispersion-strengthened copper

The cyclic deformation behavior of a dispersion-strengthened copper alloy, GlidCop Al-15, has been studied at plastic strain amplitudes in the range 0.1 pct [<=] [Delta][var epsilon][sub p]/2 [<=] 0.8 pct. Compared to pure polycrystalline copper, the dispersion-strengthened material exhibits a relatively stable cyclic response as a consequence of the dislocation substructures inherited from prior processing and stabilized by the Al[sub 2]O[sub 3] particles. These dislocation structures remain largely unaltered during the course of deformation; hence, they do not reveal any of the features classically associated with copper tested in fatigue. At low amplitudes, the fatigue lifetimes of the dispersion-strengthened copper and the base alloy are similar; however, the former is more susceptible to cracking at stress concentrations because of its substantially greater strength. This similarity in fatigue life-times is a consequence of the dispersal of both deformation and damage accumulation by the fine grain size and dislocation/particle interactions in the GlidCop alloy. The operation of these mechanisms is reflected in the fine surface slip markings and rough fracture surface features for this material.