Cu concentration dependence of the mechanical behaviour of Al-Cu alloys

1999 ◽  
Vol 564 ◽  
Author(s):  
J. P. Lokker ◽  
R. S. A. van Winden ◽  
A. M. Janssen ◽  
S. Radelaar
Keyword(s):  
Thin Films ◽  
Tensile Stress ◽  
Mechanical Behaviour ◽  
Precipitation Hardening ◽  
Solid Solution Hardening ◽  
Isothermal Hold ◽  
Solution Hardening ◽  
Stress Increase ◽  
Si Substrates ◽  
Cu Alloys

AbstractThis paper reports on the influence of the copper concentration on the mechanical behaviour during thermal cycling and during isothermal holds of Al-Cu thin films on Si substrates. The Cu concentration has been varied in the range between 0 to 1 at.%Upon heating, the films with the larger amount of Cu showed a clear maximum in compressive stress. Moreover, during cooling these samples show a tensile stress increase at the onset precipitation temperature. Further cooling below 200 °C leads to the characteristic tensile stress increase often observed for Al-Cu thin films. An isothermal hold during cooling at 250 °C leads to temporary strengthening of all Al-Cu. The extent of the strengthening is dependent on the Cu concentration and is clearly dependent on the duration of the isothermal hold. Upon further cooling the strengthening disappears and the stress develops according to the original stress temperature dependence. The observations are discussed in terms of solid solution hardening and precipitation hardening.

scholarly journals Solid Solution Hardening and Precipitation Hardening of α2-Ti3Al in Ti-Al-Nb Alloys

2017 ◽  
Vol 58 (10) ◽  
pp. 1404-1410 ◽  
Author(s):  
Kei Shimagami ◽  
Sae Matsunaga ◽  
Atsushi Yumoto ◽  
Tsutomu Ito ◽  
Yoko Yamabe-Mitarai
Keyword(s):  
Solid Solution ◽  
Precipitation Hardening ◽  
Solid Solution Hardening ◽  
Solution Hardening

Effects of Zr and Sc additions on precipitation of α-Al(FeMn)Si dispersoids under various heat treatments in Al–Mg–Si AA6082 alloys

2021 ◽  
Vol 112 (9) ◽  
pp. 706-716
Author(s):  
Kun Liu ◽  
Emad Elgallad ◽  
Chen Li ◽  
X.-Grant. Chen
Keyword(s):  
Solid Solution ◽  
Precipitation Hardening ◽  
Base Alloy ◽  
Heat Treatments ◽  
Solid Solution Hardening ◽  
Number Density ◽  
Solution Hardening ◽  
Heat Treated ◽  
The Individual

Abstract The present work investigated the influence of Zr and Sc on the evolution of α-Al(FeMn)Si dispersoids (“α-dispersoids") in Al–Mg–Si alloys. Both the individual addition of Zr and the combined additions of Sc and Zr increased the size but decreased the number density of the α-dispersoids, indicating the reduction in the formation of α-dispersoids. However, the reduction levels were the most significant when heat-treated at 350 °C in the alloy with both Sc and Zr and at 400 °C in the alloy with only Zr, which were likely related to the different interactions between intermediate B’ precipitates and α-dispersoids with the addition of Zr and Sc. Although the α-dispersoids were suppressed in the Zr/Sc-containing alloys, their microhardness was generally higher than the base alloy, which can be attributed to the strengthening contribution induced by Zr and Sc either from their solid solution hardening or the precipitation hardening of Al3Zr/Al3(Sc, Zr) dispersoids.

Progress in Creep-Resistant Steels for High Efficiency Coal-Fired Power Plants

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Fujio Abe
Keyword(s):  
Solid Solution ◽  
Creep Strength ◽  
Power Plants ◽  
Precipitation Hardening ◽  
High Efficiency ◽  
Austenitic Steels ◽  
Solid Solution Hardening ◽  
Solution Hardening ◽  
Creep Resistant Steels ◽  
Grade 91

Recent progress in creep-resistant bainitic, martensitic, and austenitic steels for high efficiency coal-fired power plants is comprehensively reviewed with emphasis on long-term creep strength and microstructure stability at grain boundaries (GBs). The creep strength enhanced ferritic (CSEF) steels, such as Grade 91 (9Cr–1Mo–0.2V–0.05Nb), Grade 92 (9Cr–0.5Mo–1.8W–VNb), and Grade 122 (11Cr–0.4Mo–2W–1CuVNb), can offer the highest potential to meet the required flexibility for ultra-supercritical (USC) power plants operating at around 600 °C, because of their smaller thermal expansion and larger thermal conductivity than austenitic steels and Ni base alloys. Further improvement of creep strength of martensitic 9 to 12Cr steels has been achieved by substituting a part or all of Mo with W and also by the addition of Co, V, Nb, and boron. A martensitic 9Cr–3W–3Co–VNb steel strengthened by boron and MX nitrides, designated MARBN, exhibits not only much higher creep strength of base metal than Grade 91, Grade 92, and Grade 122 but also substantially no degradation in creep strength due to type IV fracture in welded joints at 650 °C. High-strength bainitic 2.25 to 3Cr steels have been developed by enhancing solid solution hardening due to W and precipitation hardening due to (V,Nb)C carbides in bainitic microstructure. The improvement of creep strength of austenitic steels has been achieved by solid solution hardening due to the addition of Mo, W, and nitrogen and by precipitation hardening due to the formation of fine MX (M = Ti, Nb, X = C, N), NbCrN, M23C6, Cu phase, and Fe2(Mo,W) Laves phase. The boundary and sub-boundary hardening are shown to be the most important strengthening mechanism in creep of creep-resistant steels and is enhanced by fine dispersions of precipitates along boundaries.

Influence of W in Solid Solution on the Creep Rate of Nickel

2018 ◽  
Author(s):  
Jing Zhang ◽  
Rolf Sandström
Keyword(s):  
Solid Solution ◽  
Creep Rate ◽  
Precipitation Hardening ◽  
Solid Solution Hardening ◽  
Solution Hardening ◽  
Solute Content ◽  
High Temperature Alloys ◽  
Cottrell Atmosphere ◽  
Vital Element ◽  
Wide Usage

Ni and Ni-W binary alloys are basis for nickel based superalloys. For most nickel based superalloys, strengthening mechanisms include both solid solution hardening and precipitation hardening. W is a vital element to create solid solution hardening and to improve the creep strength. In spite of its wide usage to strengthening of high temperature alloys, the mechanisms for solid solution hardening are not fully quantified. From the assumption that it is due to the attraction of solute atoms to dislocations and formation of Cottrell atmosphere to slow down the motion of dislocations, a fundamental model has been formulated previously. In the present paper, the model is expanded by taking the stacking fault energy and strain induced vacancies into account. Important parameters in the model are the variation of the lattice constant and the shear modulus with alloying content. Models for these variations have been formulated as a function of solute content. Another important parameter is the maximum interaction energy between the dislocations and the solutes. The model can satisfactorily predict both the large difference in creep rate between pure Ni and Ni-W alloys and the comparatively smaller differences between the three investigated Ni-2W, Ni-4W and Ni-6W alloys.

Mechanical Properties of Al-Cu Films with Various Heat Treatments

1997 ◽  
Vol 473 ◽  
Author(s):  
Young-Chang Joo ◽  
Peter Müllner ◽  
Shefford P. Baker ◽  
Eduard Arzt
Keyword(s):  
Precipitation Hardening ◽  
Heat Treatments ◽  
Temperature Cycling ◽  
Solid Solution Hardening ◽  
Solution Hardening ◽  
Cu Films ◽  
Cu Content ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Compressive Flow

ABSTRACTPrecipitation and solid solution hardening have been studied in Al-Cu thin films with Cu content ranging from 0 to 2 wt%. We have changed the precipitate and dislocation structures of films having different Cu concentrations by varying the heat treatments prior to mechanical testing. Pure Al films showed the same values of tensile and compressive yield stresses at a given temperature during stress-temperature cycling. Al-Cu alloy films, however, showed larger stresses in tension than in compression. The compressive flow stress during heating could be changed by a factor of five by the initial heat treatment, but the differences disappeared above 250°C. Upon cooling from 480°C, solution hardening as well as precipitation hardening was observed in the Al-Cu films. Solution hardening is independent of Cu concentration, but for precipitation hardening, both the magnitude and the temperature range in which the mechanism is effective are sensitive to the Cu concentration. The microstructure was observed using transmission electron microscopy. The mechanical behavior is consistent with interactions between dislocations and precipitates which arise due to constraints on the film by the substrate.

The Influence of Thermal History and Alloying Elements on Temporary Strengthening of Thin Al-Cu Films

1999 ◽  
Vol 594 ◽  
Author(s):  
J. P. Lokker ◽  
G. C. A. M. Janssen ◽  
S. Radelaar
Keyword(s):  
Thin Films ◽  
Copper Concentration ◽  
Isothermal Hold ◽  
Thermally Induced ◽  
Stress Increase ◽  
Cu Films ◽  
Hold Period ◽  
Hold Temperature ◽  
Induced Stress ◽  
Large Tensile Stress

AbstractThe influence of Cu on the response of Al-Cu thin films to thermally induced stress is studied. The copper concentration is varied between 0 and 1.15 at. %. It is proposed that copper atoms which have not formed precipitates, largely affect the mechanical behaviour. This idea is supported by the following observations. An isothermal hold results in temporary strengthening of the films. The extent of this strengthening increases with copper concentration, increases with decreasing isothermal hold temperature and saturates with increasing isothermal hold period. Based on these observations the large tensile stress increase below 200 °C is ascribed to the formation of Cottrell atmospheres.

Interactions Between Al and Cr Thin Films

1976 ◽  
Vol 34 ◽  
pp. 638-639
Author(s):  
R. M. Anderson ◽  
T. M. Reith ◽  
M. J. Sullivan ◽  
E. K. Brandis
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Vacuum System ◽  
Processing Temperature ◽  
Diffusion Couples ◽  
Electronic Circuits ◽  
Intermetallic Formation ◽  
Si Substrates ◽  
Aluminum Silicon

Thin films of aluminum or aluminum-silicon can be used in conjunction with thin films of chromium in integrated electronic circuits. For some applications, these films exhibit undesirable reactions; in particular, intermetallic formation below 500 C must be inhibited or prevented. The Al films, being the principal current carriers in interconnective metal applications, are usually much thicker than the Cr; so one might expect Al-rich intermetallics to form when the processing temperature goes out of control. Unfortunately, the JCPDS and the literature do not contain enough data on the Al-rich phases CrAl7 and Cr2Al11, and the determination of these data was a secondary aim of this work.To define a matrix of Cr-Al diffusion couples, Cr-Al films were deposited with two sets of variables: Al or Al-Si, and broken vacuum or single pumpdown. All films were deposited on 2-1/4-inch thermally oxidized Si substrates. A 500-Å layer of Cr was deposited at 120 Å/min on substrates at room temperature, in a vacuum system that had been pumped to 2 x 10-6 Torr. Then, with or without vacuum break, a 1000-Å layer of Al or Al-Si was deposited at 35 Å/s, with the substrates still at room temperature.

Defects in β-SiC thin films grown on α-SiC substrates

1988 ◽  
Vol 46 ◽  
pp. 568-569
Author(s):  
Karren L. More
Keyword(s):  
Thin Films ◽  
Semiconductor Device ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Substrate Material ◽  
Growth Interface ◽  
Si Substrates ◽  
Thermal Expansion Coefficients ◽  
Device Applications ◽  
Expansion Coefficients

Beta-SiC is an ideal candidate material for use in semiconductor device applications. Currently, monocrystalline β-SiC thin films are epitaxially grown on {100} Si substrates by chemical vapor deposition (CVD). These films, however, contain a high density of defects such as stacking faults, microtwins, and antiphase boundaries (APBs) as a result of the 20% lattice mismatch across the growth interface and an 8% difference in thermal expansion coefficients between Si and SiC. An ideal substrate material for the growth of β-SiC is α-SiC. Unfortunately, high purity, bulk α-SiC single crystals are very difficult to grow. The major source of SiC suitable for use as a substrate material is the random growth of {0001} 6H α-SiC crystals in an Acheson furnace used to make SiC grit for abrasive applications. To prepare clean, atomically smooth surfaces, the substrates are oxidized at 1473 K in flowing 02 for 1.5 h which removes ∽50 nm of the as-grown surface. The natural {0001} surface can terminate as either a Si (0001) layer or as a C (0001) layer.

A Tem Study of Slip Systems in MoSi2/WSi2 Alloys

1991 ◽  
Vol 49 ◽  
pp. 942-943
Author(s):  
Stuart A. Maloy
Keyword(s):  
Solid Solution ◽  
Solid Solution Hardening ◽  
Slip Systems ◽  
High Melting ◽  
Group 14 ◽  
Solution Hardening ◽  
Brittle To Ductile Transition ◽  
High Melting Temperature ◽  
Tetragonal Unit Cell ◽  
Structural Applications

MoSi2 has recently been investigated as a potential material for high temperature structural applications. It has excellent oxidation resistance up to 1700°C, a high melting temperature, 2030°C, and a brittle-to-ductile transition temperature at 900-1000°C. WSi2 is isomorphous with MoSi2 and has a body-centered tetragonal unit cell of the space group 14/mmm. The lattice parameters are a=3.20 Å and c=7.84 Å for MoSi2 and a=3.21 Å and c=7.88 Å for WSi2. Therefore, WSi2 was added to MoSi2 to improve its strength via solid solution hardening. The purpose of this study was to investigate the slip systems in polycrystalline MoSi2/WSi2 alloys.

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