Enhanced tensile ductility in an electrodeposited nanocrystalline copper

2008 ◽  
Vol 23 (8) ◽  
pp. 2238-2244 ◽  
Author(s):  
Guoyong Wang ◽  
Zhonghao Jiang ◽  
Hanzhuo Zhang ◽  
Jianshe Lian
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Activation Volume ◽  
Large Strain ◽  
Rate Sensitivity ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Strain Rate Change ◽  
Perfect Plasticity

A fully dense nanocrystalline (nc) Cu with mean grain size of 72 nm and a broad grain size distribution was synthesized by electrodeposition. Uniaxial tensile tests were done at different strain rates and room temperature. A very high strength of 1.04 G was obtained at strain rate of 0.1 s−1. The nearly perfect plasticity with a large strain of close to 20% was displayed at specific low strain rates of 4 × 10−5 to 10−4 s−1. With increasing strain rate, the nearly perfect plasticity disappeared. Strain rate sensitivity and activation volume of the nc Cu were estimated from the flow stress at a fixed strain of 1% and a strain rate change (jump) test. It was deduced from the high strain rate sensitivity exponent of 0.08 and small activation volume of 12b3 that both dislocation and grain boundary activities would take place in this nc Cu, which explained the nearly perfect plasticity observed in the tensile test.

scholarly journals A Modified Eyring Equation for Modeling Yield and Flow Stresses of Metals at Strain Rates Ranging from 10−5to 5 × 104 s−1

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Ramzi Othman
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Large Strain ◽  
Rate Sensitivity ◽  
Industrial Applications ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Wide Range ◽  
Large Strain Rate

In several industrial applications, metallic structures are facing impact loads. Therefore, there is an important need for developing constitutive equations which take into account the strain rate sensitivity of their mechanical properties. The Johnson-Cook equation was widely used to model the strain rate sensitivity of metals. However, it implies that the yield and flow stresses are linearly increasing in terms of the logarithm of strain rate. This is only true up to a threshold strain rate. In this work, a three-constant constitutive equation, assuming an apparent activation volume which decreases as the strain rate increases, is applied here for some metals. It is shown that this equation fits well the experimental yield and flow stresses for a very wide range of strain rates, including quasi-static, high, and very high strain rates (from 10−5to 5 × 104 s−1). This is the first time that a constitutive equation is showed to be able to fit the yield stress over a so large strain rate range while using only three material constants.

Grain Refinement during Superplastic Deformation of Coarse-Grained Al-Mg-Cu Alloys

2006 ◽  
Vol 509 ◽  
pp. 75-80 ◽  
Author(s):  
M.I. Cruz-Palacios ◽  
D. Hernández-Silva ◽  
L.A. Barrales-Mora ◽  
M.A. García-Bernal
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Grain Refinement ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Mg Alloy ◽  
Coarse Grained ◽  
Dislocation Creep ◽  
Rolled Plate ◽  
Strain Rates

In the present study the superplastic behavior of Al-6%Mg–0.5%Cu and Al–8%Mg– 0.5%Cu in a coarse grain size condition has been studied. The alloys are melted in an electrical furnace under argon atmosphere. The ingots (25 mm thick) are homogenized at 400 °C during 72 h and then rolled at 430 °C to a thickness of 5 mm. The mean grain size after rolling is 55 µm for the 6%Mg alloy and 61 µm for the 8%Mg alloy. Tensile test specimens are machined from the rolled plate in the rolling direction. Strain-rate-change tests at temperatures between 300 and 450 °C and strain rates between 1x10-4 and 1x10-1 s-1 are carried out to determine the strain rate sensitivity of the flow stress. Finally, elongation to failure tests are conducted at temperatures and strain rates where the alloys show a high strain rate sensitivity. Elongations higher than 390 % are obtained for the 8%Mg alloy. It is observed that the grip regions of the deformed samples show coarser grains than the regions near to the fracture surface. This means that grain refinement takes place during deformation, suggesting that the principal deformation mechanism is dislocation creep.

Evaluation of tensile properties of fiber metal laminates under different strain rates

2021 ◽  
pp. 095440892110530
Author(s):  
Muhammad Yasir Khalid ◽  
Zia Ullah Arif ◽  
Waqas Ahmed ◽  
Hassan Arshad
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Operating Conditions ◽  
Material Behavior ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Fiber Metal Laminates ◽  
Fiber Metal

There has been an ever-going need for materials containing excellent mechanical properties, lower density, and improved fuel efficiency in the aerospace industry. To date, Fiber Metal Laminates (FMLs) are a prime choice for aerospace applications. The components of aircraft are subjected to various mechanical loadings under operating conditions; therefore, an in-depth understanding of material behavior under expected loading conditions is imperative for the meticulous design and manufacturing of these components. To evaluate the tensile behavior of the FMLs containing Aluminum 7075-T6 sheets as a metallic phase was the primary aim of this study. Furthermore, the manufactured composites were treated with the processes including surface de-greasing, mechanical abrasion, and anodizing. In order to perform mechanical characterization, uniaxial tensile tests were conducted at various strain rates 2×10−4 s−1, 5×10−4 s−1 and 8×10−4 s−1. The FMLs were fabricated through vacuum-assisted resin transfer molding (VARTM) process. The results revealed that FMLs based different combinations of the fiber and metal constituents exhibited a low degree of strain rate-sensitivity. In the case of CARALL, 1.7% increase in tensile strength was observed, and, its tensile strength was increased from 741 MPa to 754 MPa. Whereas, ARALL and GLARE laminates exhibited high degree of strain rate-sensitivity. When the strain rate is increased from 2×10−4 s−1, 5×10−4 s−1 and 8×10−4 s−1 the values are increased in the following patterns: 389 MPa, 411 MPa, and 475 MPa for GLARE laminates, and 253 MPa, 298 MPa 352 MPa for ARALL laminates. Thus, 39% and 22% increase in the tensile strengths were noted for ARALL and GLARE laminates, respectively.

Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations

2006 ◽  
Vol 503-504 ◽  
pp. 31-36 ◽  
Author(s):  
Johannes Mueller ◽  
Karsten Durst ◽  
Dorothea Amberger ◽  
Matthias Göken
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Fcc Metals ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Indentation Strain

The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.

Strain Rate Sensitivity of Mixed SAC-SnBi Solder Joints

2019 ◽  
Vol 2019 (1) ◽  
pp. 000480-000487
Author(s):  
Luke A. Wentlent ◽  
James Wilcox ◽  
Xuanyi Ding
Keyword(s):  
Melting Point ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Solder Joints ◽  
Volume Ratio ◽  
Rate Sensitivity ◽  
Thermal Exposure ◽  
Fracture Mechanisms ◽  
Eutectic System ◽  
Strain Rates

Abstract As the electronics industry continues to evolve a concerted effort has developed to implement lower melting point solders. The ability to minimize the thermal exposure that an assembly is subjected to affords significant benefits with respect to both the reliability and the materials that can be used. One of the most popular low melt solder alloys currently being investigated by the industry is the Bi-Sn eutectic system, which has a melting point of 139°C. The BiSn system itself is not particularly novel as it was posited as a SAC alternative during the initial shift from Pb based solders. While a body of knowledge currently exists regarding this system, and the near eutectic variant BiSnAg, there are still concerns regarding its ductility, especially as a function of thermal exposure and strain rate. Bismuth is widely acknowledged as a brittle element and its presence in such quantities raises concerns of not just Cu6Sn5 embrittlement but also solder fragility in high strain rate types of environments. A challenge with regards to near term implementation is that most packages are not available with BiSn solder bumps. Therefore, it will be necessary to use components already balled with SAC 305 solder. This means that the resulting solder interconnect, reflowed below conventional SAC reflow temperatures, will form a type of mixed hybrid microstructure. This non-equilibrium microstructure will be composed of two regions, one Bi-rich region which is well past saturation and a second region which is Bi-deficient. It is of specific industrial interest then to not just investigate the BiSn solder system but also within the context of a realistic mixed interconnect. Recent work by several researchers has shown that this hybrid microstructure is unstable and quite active with respect to the movement and localized concentration of the Bismuth. The degree of mixing of these two regions has been shown to be highly dependent upon reflow temperature and the paste to ball volume ratio. Mixed SAC-BiSn solder joints were formed by placing SAC 305 spheres on BiSn paste deposits for a paste to ball volume ratio of .18. These samples were then reflowed at either 175°C or 200°C. SAC 305 control samples were also made using a conventional Pb-free reflow profile with a peak temperature of 247°C. A 22 mil Cu-OSP pad on a 1.0 mm thick FR4 substrate was used for all samples. A selection of the solder joints were then isothermally aged at 90°C for 200 hours. Using a joint level micromechanical tester, ball shear tests were conducted at a range of strain rates for samples in the as-reflowed and aged state. Using this information, the strain rate sensitivity of the interconnects was mapped and correlated with the observed failure modes. Investigations into the fracture mechanisms were conducted by examining the shear fracture surface with optical and scanning electron microscopy. Additionally, the evolution of the microstructure was characterized. Results showed a clear transition from ductile solder failure to a brittle separation failure at the higher strain rates.

scholarly journals Strain-Rate-Dependent Deformation Behavior and Mechanical Properties of a Multi-Phase Medium-Manganese Steel

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 344 ◽  
Author(s):  
Simon Sevsek ◽  
Christian Haase ◽  
Wolfgang Bleck
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Deformation Behavior ◽  
Rate Sensitivity ◽  
Manganese Steel ◽  
Strain Rates ◽  
Rate Dependent ◽  
Medium Manganese Steel ◽  
Multi Phase

The strain-rate-dependent deformation behavior of an intercritically annealed X6MnAl12-3 medium-manganese steel was analyzed with respect to the mechanical properties, activation of deformation-induced martensitic phase transformation, and strain localization behavior. Intercritical annealing at 675 °C for 2 h led to an ultrafine-grained multi-phase microstructure with 45% of mostly equiaxed, recrystallized austenite and 55% ferrite or recovered, lamellar martensite. In-situ digital image correlation methods during tensile tests revealed strain localization behavior during the discontinuous elastic-plastic transition, which was due to the localization of strain in the softer austenite in the early stages of plastic deformation. The dependence of the macroscopic mechanical properties on the strain rate is due to the strain-rate sensitivity of the microscopic deformation behavior. On the one hand, the deformation-induced phase transformation of austenite to martensite showed a clear strain-rate dependency and was partially suppressed at very low and very high strain rates. On the other hand, the strain-rate-dependent relative strength of ferrite and martensite compared to austenite influenced the strain partitioning during plastic deformation, and subsequently, the work-hardening rate. As a result, the tested X6MnAl12-3 medium-manganese steel showed a negative strain-rate sensitivity at very low to medium strain rates and a positive strain-rate sensitivity at medium to high strain rates.

Temperature Effects in Al 5083 with a Bimodal Grain Size

2013 ◽  
Vol 1513 ◽  
Author(s):  
Andrew C. Magee ◽  
Leila J. Ladani
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Cold Isostatic Pressing ◽  
Milling Process ◽  
Dynamic Strain ◽  
Plastic Properties ◽  
Al 5083 Alloy ◽  
Bimodal Grain Size

ABSTRACTAn Al 5083 alloy with a bimodal grain size has been previously synthesized using a low-temperature milling process and consolidation via cold isostatic pressing (CIP). This material has been shown to exhibit greatly improved strength when compared to conventional aluminum alloys. Additionally, this material has shown sensitivity to test conditions. In this work, we studied the effects of temperature on the strain rate sensitivity of this material by examining its elastic and plastic properties though uniaxial tension tests conducted under a variety of conditions at temperatures up to 473 K. Serrated stress-strain curves were observed, indicating dynamic strain aging. Strain rate sensitivity was found to depend non-monotonically on the test temperature.

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