Solid Solution Strengthening of Mo, Re, Ta and W in Ni during High-Temperature Creep

Solid solution strengthening of the unordered γ matrix phase by alloying elements is of great importance during creep of Ni-based superalloys, particularly at high temperatures above 1000 °C. To study the role of different potent solutes, we have conducted creep experiments on binary Ni-2X alloys (X = Mo, Re, Ta, W) at 1000 °C, 1050 °C, and 1100 °C at a constant stress of 20 MPa. Compared to mechanical tests below 800 °C, where the size of the elements mostly determines the solid solution hardening contribution, the strengthening contribution of the different alloying elements above 1000 °C directly correlates with their diffusivity. Therefore, elements such as Ta that lead to strong solid solution hardening at low temperatures become less effective at higher temperatures and are exceeded by slower diffusing elements, such as Re.

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Nanoindentation investigations to study solid solution hardening in Ni-based diffusion couples

Journal of Materials Research ◽

10.1557/jmr.2009.0135 ◽

2009 ◽

Vol 24 (3) ◽

pp. 1127-1134 ◽

Cited By ~ 16

Author(s):

Oliver Franke ◽

Karsten Durst ◽

Mathias Göken

Keyword(s):

Solid Solution ◽

Solid Solution Hardening ◽

Diffusion Couples ◽

Indentation Size ◽

Careful Evaluation ◽

Solution Hardening ◽

Solid Solution Strengthening ◽

Acta Mater ◽

Solution Strengthening

In this work the hardening effect of Ta and Mo in Ni-base alloys was investigated using a combinatorial approach with diffusion couples. Furthermore, the Ni-Fe system was used as a reference system taking advantage of the full miscibility at high temperatures. Ta was chosen, as aside from having a technical relevance in the Ni-base superalloys, it also has a high miscibility in Ni. The main focus of this paper will be solid solution hardening. It will be shown that even though the determination of hardness is subject to varying indentation size effects (ISE) [Durst et al., Acta Mater.55(20), 6825 (2007)], only a few modifications are necessary to describe solid solution strengthening measured by nanoindentations using the Labusch theory [Labusch, Acta Metall.20(7), 917 (1972)]. Moreover, after a careful evaluation of the results, the data can be used to investigate solid solution hardening effects quickly and efficiently with small amounts of material.

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Deformation Mechanisms and Solid-Solution Strengthening in Ordered Alloys

MRS Proceedings ◽

10.1557/proc-213-499 ◽

1990 ◽

Vol 213 ◽

Cited By ~ 3

Author(s):

Dennis M. Dimiduk ◽

Satish Rao

Keyword(s):

Solid Solution ◽

Flow Behavior ◽

Stoichiometric Composition ◽

Dislocation Core ◽

Deformation Mechanisms ◽

Solid Solution Hardening ◽

Solid Solution Strengthening ◽

Ordered Alloys ◽

Solute Hardening

ABSTRACTFundamental to understanding the results of alloy design studies, is the need for understanding the intrinsic role of solutes in a particular compound. For many compounds such an understanding must be built from a systematic exploration of the role of deviations from the stoichiometric composition as well as the role of ternary solute additions on the variation of flow behavior. Within most intermetallic systems the problem is complicated since the fundamental mechanisms of flow are not well established and, in those systems where these mechanisms are known, thermal activation can lead to dislocation-core transformations and changes in the operative slip systems with temperature. In general, flow may be governed by more than one dislocation process at a given temperature and deformation twinning may be a major contributing deformation mechanism. The problem of isolating the mechanisms of solid-solution hardening may, therefore, require treatment as a problem of combined strengthening mechanisms operating in parallel. This paper reviews the key aspects of deformation mechanisms and solute strengthening in intermetallic alloys. Classical elastic theories of solute hardening serve as an origin, from which, the progress made to date in isolating the mechanisms of solute hardening in ordered alloys is discussed.

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The Importance of Diffusivity and Partitioning Behavior of Solid Solution Strengthening Elements for the High Temperature Creep Strength of Ni-Base Superalloys

Metallurgical and Materials Transactions A ◽

10.1007/s11661-020-06028-0 ◽

2020 ◽

Vol 51 (12) ◽

pp. 6195-6206 ◽

Cited By ~ 1

Author(s):

S. Giese ◽

A. Bezold ◽

M. Pröbstle ◽

A. Heckl ◽

S. Neumeier ◽

...

Keyword(s):

Solid Solution ◽

High Temperature ◽

Creep Resistance ◽

Elevated Temperatures ◽

Solid Solution Hardening ◽

Stress Regime ◽

Solid Solution Strengthening ◽

Solution Strengthening ◽

The Individual ◽

Partitioning Behavior

AbstractThe creep resistance of single-crystalline Ni-base superalloys at elevated temperatures depends among others on solid solution strengthening of the γ-matrix. To study the influence of various solid solution strengtheners on the mechanical properties, a series of Ni-base superalloys with the same content of different alloying elements (Ir, Mo, Re, Rh, Ru, W) or element combinations (MoW, ReMo, ReW) was investigated. Nanoindentation measurements were performed to correlate the partitioning behavior of the solid solution strengtheners with the hardness of the individual phases. The lowest γ′/γ-hardness ratio was observed for the Re-containing alloy with the strongest partitioning of Re to the γ-matrix. As a result of the creep experiments in the high-temperature/low-stress regime (1373 K (1100 °C)/140 MPa), it can be concluded that solid solution hardening in the γ-phase plays an essential role. The stronger the partitioning to the γ-phase and the lower the interdiffusion coefficient of the alloying element, the better the creep resistance. Therefore, the best creep behavior is found for alloys containing high contents of slow-diffusing elements that partition preferably to the γ-phase, particularly Re followed by W and Mo.

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Effect of Oxygen on Phase Precipitation and Mechanical Functionality in Ti-29Nb-13Ta-4.6Zr

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.436.179 ◽

2010 ◽

Vol 436 ◽

pp. 179-184 ◽

Cited By ~ 1

Author(s):

Mitsuo Niinomi ◽

Masaaki Nakai ◽

Toshikazu Akahori ◽

Harumi Tsutsumi

Keyword(s):

Solid Solution ◽

Titanium Alloys ◽

Young’S Modulus ◽

Martensite Phase ◽

Phase Precipitation ◽

Solid Solution Strengthening ◽

Orthorhombic Martensite ◽

Solution Strengthening ◽

Effect Of Oxygen

Oxygen plays very important roles in titanium and its alloys. Solute oxygen in titanium alloys leads to solid solution strengthening, suppressing the precipitation of the athermal omegaor orthorhombic martensite phase, enhancing the formation of the -case, etc. The proper using oxygen is effective to improve the mechanical functionalities of titanium alloys. However, the role of oxygen in titanium alloys is still not well understood. Therefore, the effect of oxygen on the mechanical functionalities such as strength-ductility balance, hardness, and Young’s modulus in Ti-29nb-13Ta-4.6Zr was investigated.

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Mechanisms of Solid-Solution Hardening of Single-Phase Cu-Al and Cu-Mn Alloys with a Mesh Dislocation Substructure

Izvestiya of Altai State University ◽

10.14258/izvasu(2021)4-09 ◽

2021 ◽

pp. 59-65

Author(s):

L.I. Trishkina ◽

T.V. Cherkasova ◽

A.A. Klopotov ◽

A.I. Potekaev

Keyword(s):

Solid Solution ◽

Dislocation Density ◽

Solid Solution Hardening ◽

Relative Role ◽

Solution Hardening ◽

Defective Structure ◽

Grain Sizes ◽

Electron Microscopes ◽

Scalar Dislocation Density

The dislocation structure and dislocation accumulation during deformation of polycrystalline FCC solid solutions of Cu-Al and Cu-Mn systems are studied by transmission diffraction electron microscopy. The Al content in Cu-Al alloys varies from 0.5 to 14 at.%. The Mn content in Cu-Mn alloys varies in the range of 0.4 ÷ 25 at.%. Alloys with a grain size in the range of 20 ÷ 240 µm are studied. The alloy samples are deformed by stretching at a rate of 2×10-2c-1 to failure at 293 K. The structure of samples deformed to various degrees of deformation is studied on foils using electron microscopes at an accelerating voltage of 125 kV. For each degree of deformation, the scalar dislocation density and its components are measured: statistically stored dislocations ρS and geometrically necessary dislocations ρG and some other parameters of the defective structure. The mechanisms and their contributions due to mesh and mesh-mesh dislocation substructures (DSS) are determined using the example of substructural and solid-solution hardening in polycrystalline Cu-Al and Cu-Mn alloys. The relative role of various mechanisms in the formation of the resistance to deformation of alloys at different grain sizes is determined. The role of the packaging defect energy on the value of solid-solution hardening for different grain sizes is revealed. The average scalar dislocation density is considered and determined along with its components: statistically stored dislocations ρS and geometrically necessary dislocations ρG. The dependences of the flow stress on the square root of the densities of geometrically necessary dislocations and the densities of statistically stored dislocations are found.

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Mechanical Properties and Microstructure of Strip Casted Ag-27%Cu-25%Zn-3%Sn Brazing Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.26-28.485 ◽

2007 ◽

Vol 26-28 ◽

pp. 485-488 ◽

Cited By ~ 2

Author(s):

Kee Ahn Lee ◽

Sung Jun Kim ◽

Moon Chul Kim

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Solid Solution ◽

Microstructural Analysis ◽

Mechanical Tests ◽

Rich Phase ◽

Aging Heat Treatment ◽

Solid Solution Strengthening ◽

Solution Strengthening ◽

Twin Roll

This work sought to examine the suitability of twin roll strip casting for Ag-27%Cu- 25%Zn-3%Sn brazing alloy (BAg-7A) and to investigate the mechanical properties and microstructure of the strip. The effect of aging heat treatment on the properties was also studied. This new manufacturing process has applications in the production of the brazing alloy. XRD and microstructural analysis of the Ag-27%Cu-25%Zn-3%Sn strip represented eutectic microstructure of a Cu-rich phase and a Ag-rich matrix regardless of heat treatment. The results of mechanical tests showed tensile strength of 470MPa, a significant enhancement; and an 18% elongation of the twin roll casted strip, due mainly to the solid solution strengthening of Zn atoms (~20%) in the Cu-rich phases. Tensile results showed gradually decreasing strengths and increasing elongation with aging heat treatment. Microstructural evolution and fractography were also investigated and related to the mechanical properties.

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First-principles evaluation of the effect of alloying elements on the lattice parameter of a 23Cr25NiWCuCo austenitic stainless steel to model solid solution hardening contribution to the creep strength

Materials Science and Engineering A ◽

10.1016/j.msea.2014.12.057 ◽

2015 ◽

Vol 626 ◽

pp. 213-219 ◽

Cited By ~ 29

Author(s):

P.A. Korzhavyi ◽

R. Sandström

Keyword(s):

Solid Solution ◽

Stainless Steel ◽

Austenitic Stainless Steel ◽

Creep Strength ◽

First Principles ◽

Lattice Parameter ◽

Alloying Elements ◽

Solid Solution Hardening ◽

Solution Hardening ◽

Effect Of Alloying

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Modelling of the Influence of Laves Phase on the Creep Properties in 9% Cr Steels

Volume 9: Eighth International Conference on Creep and Fatigue at Elevated Temperatures ◽

10.1115/creep2007-26417 ◽

2007 ◽

Cited By ~ 2

Author(s):

Hans Magnusson ◽

Rolf Sandstro¨m

Keyword(s):

Solid Solution ◽

Creep Strength ◽

Solute Drag ◽

Laves Phase ◽

Solid Solution Hardening ◽

Moving Frame ◽

Creep Properties ◽

Solid Solution Strengthening ◽

Solution Strengthening ◽

Multi Component System

Nucleation and growth of Laves phase are calculated for a multi-component system. Coarsening of MX, M23C6 and Laves are also determined. The influence on creep strength is discussed by analysing particle hardening and solid solution strengthening. A model for particle size distribution is presented in order to determine the amount of dislocations that can climb across particles or generate Orowan loops. The model for solid solution hardening is based on a solution of Fick’s second law with a moving frame of reference for the concentration profiles around a climbing dislocation. This is done in order to determine the slowdown in dislocations velocity due to solute drag. The results show a loss in creep strength as the Laves phase grows.

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