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Showing papers on "Creep published in 2013"


Journal ArticleDOI
TL;DR: In this article, a general survey of engineering γ-TiAl based alloys is given, but concentrates on β-solidifying alloys which show excellent hot-workability and balanced mechanical properties when subjected to adapted heat treatments.
Abstract: After almost three decades of intensive fundamental research and development activities, intermetallic titanium aluminides based on the ordered γ-TiAl phase have found applications in automotive and aircraft engine industry. The advantages of this class of innovative high-temperature materials are their low density and their good strength and creep properties up to 750 °C as well as their good oxidation and burn resistance. Advanced TiAl alloys are complex multi-phase alloys which can be processed by ingot or powder metallurgy as well as precision casting methods. Each process leads to specific microstructures which can be altered and optimized by thermo-mechanical processing and/or subsequent heat treatments. The background of these heat treatments is at least twofold, i.e., concurrent increase of ductility at room temperature and creep strength at elevated temperature. This review gives a general survey of engineering γ-TiAl based alloys, but concentrates on β-solidifying γ-TiAl based alloys which show excellent hot-workability and balanced mechanical properties when subjected to adapted heat treatments. The content of this paper comprises alloy design strategies, progress in processing, evolution of microstructure, mechanical properties as well as application-oriented aspects, but also shows how sophisticated ex situ and in situ methods can be employed to establish phase diagrams and to investigate the evolution of the micro- and nanostructure during hot-working and subsequent heat treatments.

791 citations


Book
13 Nov 2013
TL;DR: In this article, a model for kink band formation in Crystalline Solids is proposed to quantify the effect of temperature on Elastic properties. But the model is limited to the case of polycrystalline solids.
Abstract: INTRODUCTION Introduction History of the MAX Phases STRUCTURE, BONDING, AND DEFECTS Introduction Atom Coordinates, Stacking Sequences, and Polymorphic Transformations Lattice Parameters, Bond Lengths, and Interlayer Thicknesses Theoretical Considerations To Be or Not to Be Distortion of Octahedra and Trigonal Prisms Solid Solutions Defects Summary and Conclusions ELASTIC PROPERTIES, RAMAN AND INFRARED SPECTROSCOPY Introduction Elastic Constants Young's Modulus and Shear Modulus Poisson's Ratios Bulk Moduli Extrema in Elastic Properties Effect of Temperature on Elastic Properties Raman Spectroscopy Infrared Spectroscopy Summary and Conclusions THERMAL PROPERTIES Introduction Thermal Conductivities Atomic Displacement Parameters Heat Capacities Thermal Expansion Thermal Stability Summary and Conclusions ELECTRONIC, OPTICAL, AND MAGNETIC PROPERTIES Introduction Electrical Resistivities, Hall Coefficients, and Magnetoresistances Seebeck Coefficients, Theta Optical Properties Magnetic Properties Superconducting Properties Summary and Conclusions OXIDATION AND REACTIVITY WITH OTHER GASES Introduction Ti3SiC2 Tin+1AlXn Solid Solutions between Ti3AlC2 and Ti3SiC2 Cr2AlC Nb2AlC and (Ti0.5,Nb0.5)2AlC Ti2SC V2AlC and (Ti0.5,V0.5)2AlC Ti3GeC2 and Ti3(Si,Ge)C2 Ta2AlC Ti2SnC, Nb2SnC, and Hf2SnC Ti2InC, Zr2InC, (Ti0.5, Hf0.5)2InC, and (Ti0.5,Zr0.5)2InC Sulfur Dioxide, SO2 Anhydrous Hydrofluoric, HF, Gas Chlorine Gas Summary and Conclusions Appendix CHEMICAL REACTIVITY Introduction Diffusivitiy of M and A Atoms Reactions with Si, C, Metals, and Intermetallics Reactions with Molten Salts Reactions with Common Acids and Bases Summary and Conclusions DISLOCATIONS, KINKING NONLINEAR ELASTICITY, AND DAMPING Introduction Dislocations and Their Arrangements Kink Band Formation in Crystalline Solids Incipient Kink Bands Microscale Model for Kinking Nonlinear Elasticity Experimental Verification of the IKB Model Effect of Porosity Experimental Evidence for IKBs Why Microcracking Cannot Explain Kinking Nonlinear Elasticity The Preisach - Mayergoyz Model Damping Nonlinear Dynamic Effects Summary and Conclusions MECHANICAL PROPERTIES: AMBIENT TEMPERATURE Introduction Response of Quasi-Single Crystals to Compressive Loads Response of Polycrystalline Samples to Compressive Stresses Response of Polycrystalline Samples to Shear Stresses Response of Polycrystalline Samples to Flexure Stresses Response of Polycrystalline Samples to Tensile Stresses Hardness Fracture Toughness and R-Curve Behavior Fatigue Resistance Damage Tolerance Micromechanisms Responsible for High K1c, R-Curve Behavior, and Fatigue Response Thermal Sock Resistance Strain Rate Effects Solid Solution Hardening and Softeing Machinability Summary and Conclusions MECHANICAL PROPERTIES: HIGH TEMPERATURES Introduction Plastic Anisotropy, Internal Stresses, and Deformation Mechanisms Creep Response to Other Stress States Summary and Conclusions EPILOGUE Outstanding Scientific Questions MAX Phase Potential Applications Forming Processes and Sintering Outstanding Technological Issues Some Final Comments INDEX

676 citations


Journal ArticleDOI
TL;DR: A review of the available experimental evidence for brittle creep in crustal rocks, and various models developed to explain the observations can be found in this paper, where three main classes of brittle creep model have been proposed to explain these observations: phenomenological, statistical, and micromechanical.

463 citations


Journal ArticleDOI
TL;DR: In this paper, the authors studied the elastic moduli, ductile creep behavior, and brittle strength of shale-gas reservoir rocks from Barnett, Haynesville, Eagle Ford, and FortSt. John shale in a series of triaxial laboratory experiments.
Abstract: We studied the elastic moduli, ductile creep behavior, and brittle strength of shale-gas reservoir rocks from Barnett, Haynesville, Eagle Ford, and FortSt. John shale in a series of triaxial laboratory experiments. We found a strong correlation between the shale compositions, in particular, the volume of clay plus kerogen and intact rock strength, frictional strength, and viscoplastic creep. Viscoplastic creep strain was approximately linear with the applied differential stress. The reduction in sample volume during creep suggested that the creep was accommodated by slight pore compaction. In a manner similar to instantaneous strain, there was more viscoplastic creep in samples deformed perpendicular to the bedding than parallel to the bedding. The tendency to creep also correlated well with the static Young’s modulus. We explained this apparent correlation between creep behavior and elastic modulus by appealing to the stress partitioning that occurs between the soft components of the shales (clay and kerogen) and the stiff components (quartz, feldspar, pyrite, and carbonates). Through a simple 1D analysis, we found that a unique relation between the creep compliance and elastic modulus, independent of composition and orientation, can be established by considering the individual creep behavior of the soft and stiff components that arises from the stress partitioning within the rock. This appears to provide a mechanical explanation for why long-term ductile deformational properties can appear to correlate with short-term elastic properties in shale-gas reservoir rocks.

290 citations


Book
01 Oct 2013
TL;DR: In this paper, an examination of the engineering mechanics of creep is presented for those engineers involved in technologies involving high stresses and temperatures where the effect of creep cannot be ignored in the design stage, and where traditional elastic analysis is inadequate.
Abstract: This book is an examination of the engineering mechanics of creep. It will be welcomed by those engineers involved in technologies involving high stresses and temperatures where the effect of creep cannot be ignored in the design stage, and where traditional elastic analysis is inadequate. The opening chapters provide a basis for understanding the more complex topics discussed later in the book. The analysis of shells and plates leads on to the less idealized analysis of frameworks, piping and shell structures.

279 citations


Journal ArticleDOI
TL;DR: In this paper, the creep properties of calcium silicate hydrates (C-S-H) are assessed by means of nanoindentation creep experiments on a wide range of substoichiometric cement pastes.

231 citations


Journal ArticleDOI
27 Sep 2013-Science
TL;DR: A crystal growth method that employs only a cyclic heat treatment to obtain a single crystal of more than several centimeters in a copper-based shape-memory alloy is reported, providing a method of fabricating a single-crystal or large-grain structure important for shape- memory properties, magnetic properties, and creep properties, among others.
Abstract: In polycrystalline materials, grain growth occurs at elevated temperatures to reduce the total area of grain boundaries with high energy. The grain growth rate usually slows down with annealing time, making it hard to obtain grains larger than a millimeter in size. We report a crystal growth method that employs only a cyclic heat treatment to obtain a single crystal of more than several centimeters in a copper-based shape-memory alloy. This abnormal grain growth phenomenon results from the formation of a subgrain structure introduced through phase transformation. These findings provide a method of fabricating a single-crystal or large-grain structure important for shape-memory properties, magnetic properties, and creep properties, among others.

210 citations


Book ChapterDOI
TL;DR: A review of the role of pressure solution creep in the ductility of the Earth's upper crust and how this creep mechanism competes and interacts with other deformation mechanisms is presented in this article.
Abstract: The aim of this review is to characterize the role of pressure solution creep in the ductility of the Earth’s upper crust and to describe how this creep mechanism competes and interacts with other deformation mechanisms. Pressure solution creep is a major mechanism of ductile deformation of the upper crust, accommodating basin compaction, folding, shear zone development, and fault creep and interseismic healing. However, its kinetics is strongly dependent on the composition of the rocks (mainly the presence of phyllosilicates minerals that activate pressure solution) and on its interaction with fracturing and healing processes (that activate and slow down pressure solution, respectively). The present review combines three approaches: natural observations, theoretical developments, and laboratory experiments. Natural observations can be used to identify the pressure solution markers necessary to evaluate creep law parameters, such as the nature of the material, the temperature and stress conditions, or the geometry of mass transfer domains. Theoretical developments help to investigate the thermodynamics and kinetics of the processes and to build theoretical creep laws. Laboratory experiments are implemented in order to test the models and to measure creep law parameters such as driving forces and kinetic coefficients. Finally, applications are discussed for the modeling of sedimentary basin compaction and fault creep. The sensitivity of the models to time is given particular attention: viscous versus plastic rheology during sediment compaction; steady state versus non-steady state behavior of fault and shear zones. The conclusions discuss recent advances for modeling pressure solution creep and the main questions that remain to be solved.

202 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of strain rate upon the uniaxial response of UHMWPE fibres, yarns and laminates of lay-up [0/90] 48 has been measured in both the 0/90° and ±45° configurations.

173 citations


Journal ArticleDOI
TL;DR: In this article, the evolution of primary carbides, grain size, volume fraction, size and inter particle spacing of precipitates from center to edge were investigated in both as-forged and heat treated Inconel-718 disks.

151 citations


Journal ArticleDOI
TL;DR: In this article, the authors proposed the development of the martensitic-ferritic 9-12%Cr creep-resistant steels, which are being used particularly in the wrought form as tubes and pipes for fossil fuelled power stations.
Abstract: The improvement of thermal efficiency of power plants has provided the incentive for the development of the martensitic–ferritic 9–12%Cr creep-resistant steels. Good progress has been made in developing such steels, which are being used particularly in the wrought form as tubes and pipes for fossil fuelled power stations. They are also finding use in high temperature process plant within the oil and gas sector, and are being considered for use in generation IV nuclear designs. The high temperature conditions that these steels operate under in fossil fuelled power stations induce type IV cracking. This type of cracking occurs in the intercritical or fine grain region of the heated affected zone via a creep mechanism, and results in fractures with relatively little total cross-weld strain. Despite the occurrence of type IV cracking experienced in lower alloy predecessors, successor alloys have been introduced and widely used with insufficient consideration given to the consequences of welding them. ...

Journal ArticleDOI
TL;DR: In this article, a constitutive model for elasto-viscoplastic thixotropic materials is proposed, consisting of two differential equations, one for the stress and the other for the structure parameter, a scalar quantity that indicates the structuring level of the microstructure.
Abstract: A constitutive model for elasto-viscoplastic thixotropic materials is proposed. It consists of two differential equations, one for the stress and the other for the structure parameter, a scalar quantity that indicates the structuring level of the microstructure. In contrast to previous models of this kind, the structure parameter varies from zero to a positive and typically large number. The lower limit corresponds to a fully unstructured material, whereas the upper limit corresponds to a fully structured material. When the upper limit is finite, the model represents a highly shear-thinning, thixotropic, and viscoelastic liquid that possesses an apparent yield stress. When it tends to infinity, the behavior of a true yield-stress material is achieved. Predictions for rheometric flows such as constant shear rate tests, creep tests, SAOS, and large-amplitude oscillatory shear (LAOS) are presented, and it is shown that, in all cases, the trends observed experimentally are faithfully reproduced by the model. Within the framework of the model, simple explanations are given for the avalanche effect and the shear banding phenomenon. The LAOS results obtained are of particular importance because they provide a piece of information that so far is absent in the literature, namely a quantitative link between the Lissajous–Bowditch curve shapes and rheological effects such as elasticity, thixotropy, and yielding.

Journal ArticleDOI
TL;DR: In this paper, the effects of 0.06Ni and 0.5Sb additives on the microstructure and solidification behavior as well as the creep properties of Sn-1.0Ag-0.5Cu (SAC105) alloys were investigated.

Journal ArticleDOI
TL;DR: In this article, the authors used 20 years of Synthetic aperture radar acquisitions by the ERS and Envisat satellites to investigate the spatial and temporal variations of strain rates along the 35-km long creeping section of the Haiyuan fault, at the north eastern boundary of the Tibetan plateau.

07 Apr 2013
TL;DR: In this paper, the authors classified micromechanisms of damage, and developed a methodology of analysis to identify the dominant damage mechanism (or class of mechanism) from the shape of the tensile creep curve.
Abstract: Creep fracture is the end result of the accumulation of damage during creep. In this paper, micromechanisms of damage are classified, and a methodology of analysis is developed. For each mechanism, a damage-evolution law and a creep-law is derived. The result is a pair of differential equations, with the same form as that of the continuum treatment of Kachanov and Rabotnov. The equations can be integrated to give the shape of the creep curve, the time and strain to fracture, residual life, and so forth. Each mechanism exhibits a characteristic shape of creep curve, with an associated Monkman-Grant constant and creep ductility; these give guidance in selecting and using the appropriate equations. Progress is made in unifying the continuum and micromechanistic approaches to creep fracture, and a method is presented for identifying the dominant damage mechanism (or class of mechanism) from the shape of the tensile creep curve. An overview of the contents of this paper can be obtained by reading Sections 1, 2, 3 and 5.

Journal ArticleDOI
TL;DR: In this article, the authors studied the strain-rate sensitivity of ultrafine-grained aluminum (Al) and nanocrystalline nickel (Ni) with an improved nanoindentation creep method.
Abstract: The strain-rate sensitivity of ultrafine-grained aluminum (Al) and nanocrystalline nickel (Ni) is studied with an improved nanoindentation creep method. Using the dynamic contact stiffness thermal drift influences can be minimized and reliable creep data can be obtained from nanoindentation creep experiments even at enhanced temperatures and up to 10 h. For face-centered cubic (fcc) metals it was found that the creep behavior is strongly influenced by the microstructure, as nanocrystalline (nc) as well as ultrafine-grained (ufg) samples show lower stress exponents when compared with their coarse-grained (cg) counterparts. The indentation creep behavior resembles a power-law behavior with stress exponents n being ∼ 20 at room temperature. For higher temperatures the stress exponents of ufg-Al and nc-Ni decrease down to n ∼ 5. These locally determined stress exponents are similar to the macroscopic exponents, indicating that similar deformation mechanisms are acting during indentation and macroscopic deformation. Grain boundary sliding found around the residual indentations is related to the motion of unconstrained surface grains.

Journal ArticleDOI
TL;DR: In this article, the effects of the external stress and aging temperature on the hardness and precipitation process in a typical Al-Cu-Mg alloy (2024-T3 aluminum alloy) were studied by uniaxial tensile creep experiments.
Abstract: Exposure of Al–Cu–Mg alloys to an elastic loading, either for “creep age forming” or other manufacturing processes at relatively high temperature, will lead to microstructural changes in materials. Effects of the external stress and creep aging temperature on the hardness and precipitation process in a typical Al–Cu–Mg alloy (2024-T3 aluminum alloy) were studied by uniaxial tensile creep experiments. Also, the effects of aging temperature on the age-hardening curves of 2024-T3 aluminum alloy were studied by stress-free-aged experiments. It is found that the precipitation process is very sensitive to the external stress and aging temperature. Temperatures of 423, 448, and 473 K are validated as the “under aging”, “peak aging” and “over aging” temperatures, respectively. An external stress can accelerate the precipitation hardening (also called age hardening) of 2024-T3 aluminum alloy. The large external stress and high aging temperature easily make the preferential precipitation process as SSS →GPB→ S ″ → S ′ → S , and S phase (Al 2 CuMg) is the main precipitate under the experimental conditions. With the increase of the external stress and creep aging temperature, S phase easily grows up and coarsens. Meanwhile, the creep aging treatment results in the discontinuous distribution of precipitation phases on grain boundaries, which can improve the corrosion-resistance of 2024-T3 aluminum alloy.

Journal ArticleDOI
TL;DR: In this paper, a 3D dislocation dynamics model is used to study the evolution of the dislocation substructure in a single-crystal superalloy for different climb rates and loading conditions.

Journal ArticleDOI
TL;DR: In this article, a new creep element, referred to as the variable-viscosity Abel dashpot, is proposed to characterize damage growth in salt rock samples during creep tests.
Abstract: Based on the definition of the constant-viscosity Abel dashpot, a new creep element, referred to as the variable-viscosity Abel dashpot, is proposed to characterize damage growth in salt rock samples during creep tests. Ultrasonic testing is employed to determine a formula of the variable viscosity coefficient, indicating that the change of the variable viscosity coefficient with the time meets a negative exponent law. In addition, by replacing the Newtonian dashpot in the classical Nishihara model with the variable-viscosity Abel dashpot, a damage-mechanism-based creep constitutive model is proposed on the basis of time-based fractional derivative. The analytic solution for the fractional-derivative creep constitutive model is presented. The parameters of the fractional derivative creep model are determined by the Levenberg–Marquardt method on the basis of the experimental results of creep tests on salt rock. Furthermore, a sensitivity study is carried out, showing the effects of stress level, fractional derivative order and viscosity coefficient exponent on creep strain of salt rock. It is indicated that the fractional derivative creep model proposed in the paper provides a precise description of full creep regions in salt rock, i.e., the transient creep region (the primary region), the steady-state creep region (the secondary region) and the accelerated creep region (the tertiary region).

Journal ArticleDOI
TL;DR: The high-temperature and low-stress creep of the Ni-based superalloy LEK 94 is investigated in this article, comparing the tensile creep behavior of miniature creep specimens in [0, 0, 1] and [1, 1, 0] directions.

Journal ArticleDOI
TL;DR: In this paper, Bower et al. used finite element simulations to establish the influences of finite indenter geometry and transients caused by elasticity, and explored experimentally using amorphous selenium as a model material.
Abstract: New experimental methods are developed to measure the uniaxial power-law creep parameters α and n in the relation e = α σ n ( e is the creep strain rate and σ is the creep stress) from indentation data obtained with a conical or pyramidal indenter. The methods are based on an analysis of Bower et al., which relates the indentation creep rate to the uniaxial creep parameters based on simple assumptions about the constitutive behavior ( Bower et al., 1993 ). Using finite element simulations to establish the influences of finite indenter geometry and transients caused by elasticity, the proposed methods are explored experimentally using amorphous selenium as a model material. This material is well suited for the study because it creeps at temperatures slightly above ambient in a load-history independent fashion with a stress exponent close to unity. Indentation creep tests were conducted with a Berkovich indenter using three different loading methods. With a few notable exceptions, the values of both α and n derived from the indentation data are generally in good agreement with those measured in uniaxial compression tests, thus demonstrating the validity of the approach.

Book
08 May 2013
TL;DR: The failure theory for isotropic materials failure behavior for fiber composite laminates is described in this article, where the authors define yield stress and failure stress (strength) for fiber composites.
Abstract: 1 The perspective on failure and direction of approach 2 History, conditions, and requirements 3 Isotropic baselines 4 The failure theory for isotropic materials 5 Isotropic materials failure behavior 6 Experimental and theoretical evaluation 7 Isotropic materials failure examples 8 The ductile/brittle transition for isotropic materials 9 Defining yield stress and failure stress (strength) 10 Fracture mechanics 11 Anisotropic, unidirectional fiber composites failure 12 Anisotropic, fiber composite laminates failure 13 Micromechanics failure analysis 14 Nanomechanics failure analysis 15 Damage, cumulative damage, creep, and fatigue failure 16 Probabilistic failure and probabilistic life prediction

Journal ArticleDOI
TL;DR: In this paper, the authors presented a new constitutive model describing the mechanical behavior of concrete at early age and beyond, which amalgamates the microplane model and the solidification-microprestress theory and takes into account all the most significant aspects of concrete behavior, such as creep, shrinkage, thermal deformation, and cracking starting from the initial stages of curing up to several years of age.

Journal ArticleDOI
TL;DR: In this paper, the authors used several theoretical models to establish the relations between CNT dispersion and final creep and creep-recovery behaviors of nanocomposites and showed that the presence of CNTs leads to a significant improvement of creep resistance of PU.
Abstract: The polyurethane (PU) nanocomposites containing carbon nanotubes (CNTs) were prepared through in situ polymerization for the creep study. The results show that the presence of CNTs leads to a significant improvement of creep resistance of PU. However, this creep resistance does not increase monotonously with increase of CNT contents because it is highly dependent on the dispersion of CNTs. Several theoretical models were then used to establish the relations between CNT dispersion and final creep and creep–recovery behaviors of nanocomposites. The as-obtained viscoelastic and viscoplastic parameters of PU matrix and structural parameters of CNTs further confirmed the retardation effect by CNTs during creep of the nanocomposite systems. Besides, the time–temperature superposition (TTS) principle was also employed in this work to make a further evaluation on the creep of PU/CNT nanocomposites with long-term time scale.

Journal ArticleDOI
TL;DR: In this paper, numerical simulations show that stable fault slip on faults in California also require the presence of a shallow, unstable layer of rock, the thickness of which influences the duration of the creep event.
Abstract: Stable fault slip, or creep, is thought to occur in unconsolidated sediments that form shallow parts of continental strike-slip faults. Numerical simulations show that creep events observed on faults in California also require the presence of a shallow, unstable layer of rock, the thickness of which influences the duration of the creep event.

Journal ArticleDOI
TL;DR: In this article, the deformation behavior of grade 91 steel was studied in the temperature range of 600-700°C and at stresses of 35-350 MPa, and the data were analyzed in terms of Monkman-Grant relation and Larson-Miller parameter.
Abstract: Grade 91 steel is considered a potential structural material for advanced nuclear reactors. The creep deformation behavior of Grade 91 steel was studied in the temperature range of 600–700 °C and at stresses of 35–350 MPa. The data were analyzed in terms of Monkman-Grant relation and Larson–Miller parameter. Creep damage tolerance factor and stress exponent were used to identify the cause of creep damage. The fracture surface morphology of the ruptured specimens was studied by scanning electron microscopy to elucidate the failure mechanisms. Fracture mechanism map for Grade 91 steel was developed based on the available material parameters and experimental observations.

01 Jan 2013
TL;DR: In this article, the authors examined the creep behavior of aluminized Ni-based single crystal superalloy TMS-75 with {100} and {110} side-surfaces.
Abstract: We examined the creep behavior of aluminized Ni-based single crystal superalloy TMS-75 with {100} and {110} side-surfaces. The specimens were aluminized by pack aluminizing treatment at 1000 1C for 5 h under argon flow. The creep rupture tests were performed at 900 1C under a stress of 392 MPa. The stress orientation of all of the specimens was within 41 of /001S. It was evident that the {100} specimens exhibited higher creep rupture lives compared to the {110} specimens, indicating that anisotropy of the secondary orientation—which is normal in the primary orientation—occurred. The anisotropic creep behavior of the aluminized specimens was induced primarily by the different arrangements of {111} /101S slip systems between the two side-surface orientations. The gradient of hardness values in the coating-to-substrate regions and depth of TCP penetration were additional degradation factors.

Journal ArticleDOI
TL;DR: In this paper, the authors presented a complete theoretical accounting of the thermomechanical coupling within a viscoplastic model to predict the time, temperature, and stress state dependent mechanical behavior of amorphous glassy polymers.

Journal ArticleDOI
TL;DR: In this paper, the role of intermetallic compounds on mechanical and creep behavior of Bi-Sn-based alloys has been investigated by dynamic resonance technique and Vickers indentation testing at room temperature and compared to the traditional Pb-Sn eutectic alloy.
Abstract: Mechanical properties and indentation creep of the melt-spun process Bi–42 wt%Sn, Bi–40 wt%Sn–2 wt%In, Bi–40 wt%Sn–2 wt%Ag and Bi–38 wt%Sn–2 wt%In–2 wt%Ag were studied by dynamic resonance technique and Vickers indentation testing at room temperature and compared to that of the traditional Sn–37 wt%Pb eutectic alloy. The results show that the structure of Bi–42 wt%Sn alloy is characterized by the presence of rhombohedral Bi and body centered tetragonal β-Sn. The two ternary alloys exhibit additional constituent phases of intermetallic compounds SnIn19 for Bi–40 wt%Sn–2 wt%In and e-Ag3Sn for Bi–40 wt%Sn–2 wt%Ag alloys. Attention has been paid to the role of intermetallic compounds on mechanical and creep behavior. The In and Ag containing solder alloy exhibited a good combination of higher creep resistance, good mechanical properties and lower melting temperature as compared with Pb–Sn eutectic solder alloy. This was attributed to the strengthening effect of Bi as a strong solid solution element in the Sn matrix and formation of intermetallic compounds β-SnBi, e-Ag3Sn and InSn19 which act as both strengthening agent and grain refiner in the matrix of the material. Addition of In and Ag decreased the melting temperature of Bi–Sn lead-free solder from 143 °C to 133 °C which was possible mainly due to the existence of InSn19 and Ag3Sn intermetallic compounds. Elastic constants, internal friction and thermal properties of Bi–Sn based alloys have been studied and analyzed.

Journal ArticleDOI
TL;DR: In this article, the effects of tungsten and tantalum contents on impact, tensile, low cycle fatigue and creep properties of reduced activation Ferritic-Martensitic (RAFM) steel were studied to develop India-specific RAFM steel.