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.

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.

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.

Solid solution hardening and softening in MoSi2 alloys

2001 ◽  
Vol 44 (6) ◽  
pp. 879-884 ◽  
Author(s):  
A.A Sharif ◽  
A Misra ◽  
J.J Petrovic ◽  
T.E Mitchell
Keyword(s):  
Solid Solution ◽  
Solid Solution Hardening ◽  
Solution Hardening ◽  
Hardening And Softening

Solid-solution hardening in b c c metals

1980 ◽  
Vol 15 (1) ◽  
pp. 253-254 ◽  
Author(s):  
M. Z. Butt ◽  
P. Feltham
Keyword(s):  
Solid Solution ◽  
Solid Solution Hardening ◽  
Solution Hardening

scholarly journals Solid Solubility and Solid Solution Hardening of Boron in NiAl

1993 ◽  
Vol 57 (3) ◽  
pp. 356-361 ◽  
Author(s):  
Yi Tan ◽  
Tetsumori Shinoda ◽  
Yoshinao Mishima ◽  
Tomoo Suzuki
Keyword(s):  
Solid Solution ◽  
Solid Solubility ◽  
Solid Solution Hardening ◽  
Solution Hardening

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.

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