scholarly journals Mechanical Properties and Microstructure of a NiCrFeCoMn High-Entropy Alloy Deformed at High Strain Rates

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 892 ◽  
Author(s):  
Bingfeng Wang ◽  
Xianrui Yao ◽  
Chu Wang ◽  
Xiaoyong Zhang ◽  
Xiaoxia Huang
Keyword(s):  
Mechanical Properties ◽  
Flow Stress ◽  
High Strain ◽  
High Entropy Alloy ◽  
Crystallographic Structure ◽  
Strain Rates ◽  
Deformation Bands ◽  
High Strain Rates ◽  
High Entropy ◽  
Arc Melting

The equiatomic NiCrFeCoMn high-entropy alloy prepared by arc melting has a single crystallographic structure. Mechanical properties and microstructure of the NiCrFeCoMn high-entropy alloy deformed at high strain rates (900 s−1 to 4600 s−1) were investigated. The yield strength of the NiCrFeCoMn high-entropy alloy is sensitive to the change of high strain rates. Serration behaviors were also observed on the flow stress curves of the alloy deformed at the strain rates ranging from 900 s−1 to 4600 s−1. The Zerilli–Armstrong constitutive equation can be used to predict the flow stress curves of the NiCrFeCoMn high-entropy alloy. Large amounts of deformation bands led to obvious serration behaviors of the NiCrFeCoMn high-entropy alloy under dynamic loading.

scholarly journals Mechanical Properties and Serration Behavior of a NiCrFeCoMn High-Entropy Alloy at High Strain Rates

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3722
Author(s):  
Ruoyu Liu ◽  
Xianrui Yao ◽  
Bingfeng Wang
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
High Strain ◽  
True Strain ◽  
Strain Curve ◽  
True Stress ◽  
High Entropy Alloy ◽  
Strain Rates ◽  
High Entropy ◽  
Serration Behavior

Serration behavior is a kind of plastic instability phenomenon of materials, which widely exists in the high-entropy alloys and has influence on microstructure and mechanical properties. In this work, the microstructure and mechanical properties of a NiCrFeCoMn high-entropy alloy (HEA) were studied under high-speed impact. The microstructure of a NiCrFeCoMn HEA were investigated by optical microscope (OM), scanning electron microscope (SEM), electron backscatter diffraction (EBSD), and transmission electron microscope (TEM). The dislocation density increased with the true strain at high-strain-rate deformation, and the dislocations can be hindered and released continually by the twin layers, resulting in serration on the true stress—true strain curve. When values of the strain rates are 1250, 2000 and 4800 s−1, the yield strength of the deformed NiCrFeCoMn HEA are 510, 525 and 680 MPa, respectively. Moreover, the fluctuation of the serration became more serious with the increasing of the strain rate. Compared with the as-cast NiCrFeCoMn HEA, the true stress—true strain curve of the deformed NiCrFeCoMn HEAwas smoother.

A method for determining the main mechanical properties of soft soils at high strain rates (103–105 s−1) and load amplitudes up to several gigapascals

2005 ◽  
Vol 31 (6) ◽  
pp. 530-531 ◽  
Author(s):  
A. M. Bragov ◽  
A. K. Lomunov ◽  
I. V. Sergeichev ◽  
W. Proud ◽  
K. Tsembelis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Strain ◽  
Strain Rates ◽  
High Strain Rates ◽  
Soft Soils

INVESTIGATING THE INFLUENCE OF ENVIRONMENTAL CONDITIONING ON EPOXY RESINS AT QUASISTATIC AND HIGH STRAIN RATES FOR MATERIAL OPERATING LIMIT

2021 ◽  
Author(s):  
SAGAR M. DOSHI, SAGAR M. DOSHI, ◽  
NITHINKUMAR MANOHARAN ◽  
BAZLE Z. (GAMA) HAQUE, ◽  
JOSEPH DEITZEL ◽  
JOHN W. GILLESPIE, JR.
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Yield Stress ◽  
High Strain ◽  
Operating Conditions ◽  
Strain Rates ◽  
High Strain Rates ◽  
Stress Strain ◽  
Wide Range ◽  
Environmental Aging

Epoxy resin-based composite panels used for armors may be subjected to a wide range of operating temperatures (-55°C to 76°C) and high strain rates on the order of 103-104 s-1. Over the life cycle, various environmental factors also affect the resin properties and hence influence the performance of the composites. Therefore, it is critical to determine the stress-strain behavior of the epoxy resin over a wide range of strain rates and temperatures for accurate multi-scale modeling of composites and to investigate the influence of environmental aging on the resin properties. Additionally, the characterization of key mechanical properties such as yield stress, modulus, and energy absorption (i.e. area under the stress-strain curve) at varying temperatures and moisture can provide critical data to calculate the material operating limits. In this study, we characterize mechanical properties of neat epoxy resin, SC-15 (currently used in structural armor) and RDL-RDC using uniaxial compression testing. RDL-RDC, developed by Huntsman Corporation, has a glass transition temperature of ~ 120°C, compared to ~ 85°C of SC-15. A split Hopkinson pressure bar is used for high strain rate testing. Quasistatic testing is conducted using a screw-driven testing machine (Instron 4484) at 10-3 s-1 and 10-1 s-1 strain rates and varying temperatures. The yield stress is fit to a modified Eyring model over the varying strain rates at room temperature. For rapid investigation of resistance to environmental aging, accelerated aging tests are conducted by immersing the specimens in 100°C water for 48 hours. Specimens are conditioned in an environmental chamber at 76 °C and 88% RH until they reach equilibrium. Tests are then conducted at five different temperatures from 0°C to 95°C, and key mechanical properties are then plotted vs. temperature. The results presented are an important step towards developing a methodology to identify environmental operating conditions for composite ground vehicle applications.

scholarly journals Dynamic Mechanical Properties and Microstructure of an (Al0.5CoCrFeNi)0.95Mo0.025C0.025 High Entropy Alloy

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1154
Author(s):  
Bingfeng Wang ◽  
Chu Wang ◽  
Bin Liu ◽  
Xiaoyong Zhang
Keyword(s):  
Mechanical Properties ◽  
Shear Band ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Dynamic Mechanical Properties ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Dynamic Mechanical

The dynamic mechanical properties and microstructure of the (Al0.5CoCrFeNi)0.95Mo0.025C0.025 high entropy alloy (HEA) prepared by powder extrusion were investigated by a split Hopkinson pressure bar and electron probe microanalyzer and scanning electron microscope. The (Al0.5CoCrFeNi)0.95Mo0.025C0.025 HEA has a uniform face-centered cubic plus body-centered cubic solid solution structure and a fine grain-sized microstructure with a size of about 2 microns. The HEA possesses an excellent strain hardening rate and high strain rate sensitivity at a high strain rate. The Johnson–Cook plastic model was used to describe the dynamic flow behavior. Hat-shaped specimens with different nominal strain levels were used to investigate forced shear localization. After dynamic deformation, a thin and short shear band was generated in the designed shear zone and then the specimen quickly fractured along the shear band.

Microstructural and Dynamic Mechanical Characterization of Biodegradable Magnesium-Calcium Alloy for Orthopedic Implants

2014 ◽  
Author(s):  
V. S. Brooks ◽  
Y. B. Guo
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Orthopedic Implants ◽  
Strain Rates ◽  
High Strain Rates ◽  
Static Compression ◽  
Metallic Biomaterial

Magnesium-Calcium (Mg-Ca) alloy is an emerging metallic biomaterial for manufacturing biodegradable orthopedic implants. However, very few studies have been conducted on mechanical properties of the bi-phase Mg-Ca alloy, especially at the high strain rates often encountered in manufacturing processes. The mechanical properties are critical to design and manufacturing of Mg-Ca implants. The objective of this study is to study the microstructural and mechanical properties of Mg-Ca0.8 (wt %) alloy. Both elastic and plastic behaviors of the Mg-Ca0.8 alloy were characterized at different strains and strain rates in quasi-static tension and compression testing as well as dynamic split-Hopkinson pressure bar (SHPB) testing. It has been shown that Young’s modulus of Mg-Ca0.8 alloy in quasi-static compression is much higher than those at high strain rates. Yield strength and ultimate strength of the material are very sensitive to strain rates and increase with strain rate in compression. Strain softening also occurs at large strains in dynamic compression. Furthermore, quasi-static mechanical behavior of the material in tension is very different from that in compression. The stress-strain data was repeatable with reasonable accuracy in both deformation modes. In addition, a set of material constants for the internal state variable plasticity model has been obtained to model the dynamical mechanical behavior of the novel metallic biomaterial.

Comparative Study of the Dynamic Behavior of AA2519 Aluminum Alloy in T6 and T8 Temper Conditions

2019 ◽  
Author(s):  
Adewale Olasumboye ◽  
Gbadebo Owolabi ◽  
Olufemi Koya ◽  
Horace Whitworth ◽  
Nadir Yilmaz
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Stress Response ◽  
Flow Stress ◽  
Yield Strength ◽  
Strain Rate ◽  
High Strain ◽  
Second Phase ◽  
Strain Rates ◽  
High Strain Rates

Abstract This study investigates the dynamic response of AA2519 aluminum alloy in T6 temper condition during plastic deformation at high strain rates. The aim was to determine how the T6 temper condition affects the flow stress response, strength properties and microstructural morphologies of the alloy when impacted under compression at high strain rates. The specimens (with aspect ratio, L/D = 0.8) of the as-cast alloy used were received in the T8 temper condition and further heat-treated to the T6 temper condition based on the standard ASTM temper designation procedures. Split-Hopkinson pressure bar experiment was used to generate true stress-strain data for the alloy in the range of 1000–3500 /s strain rates while high-speed cameras were used to monitor the test compliance with strain-rate constancy measures. The microstructures of the as received and deformed specimens were assessed and compared for possible disparities in their initial microstructures and post-deformation changes, respectively, using optical microscopy. Results showed no clear evidence of strain-rate dependency in the dynamic yield strength behavior of T6-temper designated alloy while exhibiting a negative trend in its flow stress response. On the contrary, AA2519-T8 showed marginal but positive response in both yield strength and flow behavior for the range of strain rates tested. Post-deformation photomicrographs show clear disparities in the alloys’ initial microstructures in terms of the second-phase particle size differences, population density and, distribution; and in the morphological changes which occurred in the microstructures of the different materials during large plastic deformation. AA2519-T6 showed a higher susceptibility to adiabatic shear localization than AA2519-T8, with deformed and bifurcating transformed band occurring at 3000 /s followed by failure at 3500 /s.

Sign in / Sign up

Export Citation Format

Share Document