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Zhirui Wang - One of the best experts on this subject based on the ideXlab platform.
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A Composite Nature of cyclic strain accommodation mechanisms of accumulative roll bonding (ARB) processed Cu sheet materials
Materials Science and Engineering: A, 2011Co-Authors: Charles C.f. Kwan, Zhirui WangAbstract:A systematic investigation of the cyclic deformation behavior of OFHC copper processed by 7 cycles of accumulative roll bonding has been carried out. The ARB copper shows a unique Composite Natured microstructure with components of various grain sizes. Upon cyclic deformation, a general cyclic softening trend was observed. Due to the Composite Natured of the ARB copper microstructure, several micro-mechanisms have been observed to have activated for cyclic strain accommodation. These mechanisms were found to be activated in sequence rather than concurrently. The first of the mechanisms to activate is believed to be slip found in the pre-existing large equiaxed grains. Following the exhaustion of the above, the pre-existing shear bands were re-activated and further developed. It is believed that the strain incompatibility between the grains within the shear band and those outside was partially responsible for the coarsening of grains along the shear bands. The cyclic softening observed is believed to be related to the grain coarsening along the path of strain localization. However, due to the limited ductility and the abundance of crack nucleation sites, the cyclic lifespan of this ARB material was found not long enough for the extensive grain coarsening necessary in the development of a macro shear band. In an attempt to understand the behavior observed, the consideration of using a Composite model is also discussed. © 2010 Elsevier B.V
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A Composite Nature of cyclic strain accommodation mechanisms of accumulative roll bonding (ARB) processed Cu sheet materials
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: Charles C.f. Kwan, Zhirui WangAbstract:A systematic investigation of the cyclic deformation behavior of OFHC copper processed by 7 cycles of accumulative roll bonding has been carried out. The ARB copper shows a unique Composite Natured microstructure with components of various grain sizes. Upon cyclic deformation, a general cyclic softening trend was observed. Due to the Composite Natured of the ARB copper microstructure, several micro-mechanisms have been observed to have activated for cyclic strain accommodation. These mechanisms were found to be activated in sequence rather than concurrently. The first of the mechanisms to activate is believed to be slip found in the pre-existing large equiaxed grains. Following the exhaustion of the above, the pre-existing shear bands were re-activated and further developed. It is believed that the strain incompatibility between the grains within the shear band and those outside was partially responsible for the coarsening of grains along the shear bands. The cyclic softening observed is believed to be related to the grain coarsening along the path of strain localization. However, due to the limited ductility and the abundance of crack nucleation sites, the cyclic lifespan of this ARB material was found not long enough for the extensive grain coarsening necessary in the development of a macro shear band. In an attempt to understand the behavior observed, the consideration of using a Composite model is also discussed.
Charles C.f. Kwan - One of the best experts on this subject based on the ideXlab platform.
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A Composite Nature of cyclic strain accommodation mechanisms of accumulative roll bonding (ARB) processed Cu sheet materials
Materials Science and Engineering: A, 2011Co-Authors: Charles C.f. Kwan, Zhirui WangAbstract:A systematic investigation of the cyclic deformation behavior of OFHC copper processed by 7 cycles of accumulative roll bonding has been carried out. The ARB copper shows a unique Composite Natured microstructure with components of various grain sizes. Upon cyclic deformation, a general cyclic softening trend was observed. Due to the Composite Natured of the ARB copper microstructure, several micro-mechanisms have been observed to have activated for cyclic strain accommodation. These mechanisms were found to be activated in sequence rather than concurrently. The first of the mechanisms to activate is believed to be slip found in the pre-existing large equiaxed grains. Following the exhaustion of the above, the pre-existing shear bands were re-activated and further developed. It is believed that the strain incompatibility between the grains within the shear band and those outside was partially responsible for the coarsening of grains along the shear bands. The cyclic softening observed is believed to be related to the grain coarsening along the path of strain localization. However, due to the limited ductility and the abundance of crack nucleation sites, the cyclic lifespan of this ARB material was found not long enough for the extensive grain coarsening necessary in the development of a macro shear band. In an attempt to understand the behavior observed, the consideration of using a Composite model is also discussed. © 2010 Elsevier B.V
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A Composite Nature of cyclic strain accommodation mechanisms of accumulative roll bonding (ARB) processed Cu sheet materials
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: Charles C.f. Kwan, Zhirui WangAbstract:A systematic investigation of the cyclic deformation behavior of OFHC copper processed by 7 cycles of accumulative roll bonding has been carried out. The ARB copper shows a unique Composite Natured microstructure with components of various grain sizes. Upon cyclic deformation, a general cyclic softening trend was observed. Due to the Composite Natured of the ARB copper microstructure, several micro-mechanisms have been observed to have activated for cyclic strain accommodation. These mechanisms were found to be activated in sequence rather than concurrently. The first of the mechanisms to activate is believed to be slip found in the pre-existing large equiaxed grains. Following the exhaustion of the above, the pre-existing shear bands were re-activated and further developed. It is believed that the strain incompatibility between the grains within the shear band and those outside was partially responsible for the coarsening of grains along the shear bands. The cyclic softening observed is believed to be related to the grain coarsening along the path of strain localization. However, due to the limited ductility and the abundance of crack nucleation sites, the cyclic lifespan of this ARB material was found not long enough for the extensive grain coarsening necessary in the development of a macro shear band. In an attempt to understand the behavior observed, the consideration of using a Composite model is also discussed.
Marco Martini - One of the best experts on this subject based on the ideXlab platform.
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The Composite Nature of the thermoluminescence UV emission of quartz
Journal of Luminescence, 2016Co-Authors: Mauro Fasoli, Marco MartiniAbstract:Abstract The radioluminescence (RL) spectra of three types of quartz have been compared to those obtained from wavelength resolved thermally stimulated luminescence (TSL) measurements. A detailed numerical deconvolution into Gaussian components allowed to identify which of the bands are involved in either types of luminescence processes. The blue “A band” at 2.51 eV was confirmed to dominate both RL and TSL spectra in samples exposed to prolonged irradiation. The UV emission of the 110 °C TSL peak was found to be Composite. Analogously to what previously reported for RL spectra, an annealing at 500 °C for 10 min induced a strong enhancement of the “C band” at 3.42 eV. This effect was particularly evident in natural and pre-irradiated quartz. A second intense UV component, the “M band” at 3.7 eV, was found to contribute to both TSL and RL spectra of samples annealed at 1000 °C for 10 min. A further broad UV emission seems to be involved only in RL emission but not in the TSL one.
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Defect studies in quartz: Composite Nature of the blue and UV emissions
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2014Co-Authors: Marco Martini, Mauro Fasoli, I VillaAbstract:Abstract Quartz is an extremely diffused natural luminescence dosimeter. Thanks to the presence of traps and luminescence centres, its TSL and OSL (Thermally and Optically Stimulated Luminescence) properties have been extensively exploited. Quartz is then used for archaeological and geological dating and is one of the most useful materials for accident dosimetry. Many luminescence emissions are known to be present in the OSL and TSL of quartz. Three main emission bands are always reported, as the red, blue and UV bands, centred at around 650, 470, and 360–380 nm, respectively. Although the assignment of the luminescence emissions to specific defect centres in quartz is still undefined, a thorough analysis of the radioluminescence emissions and their response to irradiation and thermal treatments turned out to be very useful in understanding many features. Specifically, the presence of the same emission bands in natural and synthetic quartz and their dependence on the presence of extrinsic impurities is a common characteristic. The main impurities involve Al ions substituting Si ones and charge compensated by nearby either alkali ions, H + , or a hole. The emission spectra dynamics evidenced in our experiment confirm the role of Al-related centres in the luminescence properties of quartz. From the measurements presented in this paper the Composite Nature of the “blue” emission is confirmed. Two bands labelled as A at 2.5 eV and B at 2.8 eV contribute to the emission in this region, their behaviour being different as a function of irradiation. More complex is the picture in the UV region, where, besides the already detected C and D bands at 3.4 eV and 3.9 eV, respectively, two further emissions have been detected at 3.1 eV and 3.7 eV. Despite both the 3.4 eV and the 3.7 eV bands are shown to be affected by thermal treatments, the annealing temperature dependence of their intensity is markedly different. In fact, whereas the C band intensity, at 3.4 eV, increases after annealing at 500 °C followed by a decrease at higher temperatures, the 3.7 eV intensity is strongly enhanced by annealing at temperature above 700 °C and reaches its highest value after annealing at around 1000 °C. In the light of these results a number of already known features of quartz emissions should be reconsidered.
Ulfg Meisner - One of the best experts on this subject based on the ideXlab platform.
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testing the χc1p Composite Nature of the pc 4450
Physics Letters B, 2015Co-Authors: Ulfg Meisner, J A OllerAbstract:Abstract Making use of a recently proposed formalism, we analyze the Composite Nature of the P c ( 4450 ) resonance observed by LHCb. We show that the present data suggest that this state is almost entirely made of a χ c 1 and a proton, due to the close proximity to this threshold. This also suppresses the decay modes into other, lighter channels, in our study represented by J / Ψ p . We further argue that this is very similar to the case of the scalar meson f 0 ( 980 ) which is located closely to the K K ¯ threshold and has a suppressed decay into the lighter ππ channel.
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testing the chi_ c1 p Composite Nature of the p_c 4450
arXiv: High Energy Physics - Phenomenology, 2015Co-Authors: Ulfg Meisner, J A OllerAbstract:Making use of a recently proposed formalism, we analyze the Composite Nature of the $P_c(4450)$ resonance observed by LHCb. We show that the present data suggest that this state is almost entirely made of a $\chi_{c1}$ and a proton, due to the close proximity to this threshold. This also suppresses the decay modes into other, lighter channels, in our study represented by $J/\Psi p$. We further argue that this is very similar to the case of the scalar meson $f_0(980)$ which is located closely to the $K\bar K$ threshold and has a suppressed decay into the lighter $\pi\pi$ channel.
J A Oller - One of the best experts on this subject based on the ideXlab platform.
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testing the χc1p Composite Nature of the pc 4450
Physics Letters B, 2015Co-Authors: Ulfg Meisner, J A OllerAbstract:Abstract Making use of a recently proposed formalism, we analyze the Composite Nature of the P c ( 4450 ) resonance observed by LHCb. We show that the present data suggest that this state is almost entirely made of a χ c 1 and a proton, due to the close proximity to this threshold. This also suppresses the decay modes into other, lighter channels, in our study represented by J / Ψ p . We further argue that this is very similar to the case of the scalar meson f 0 ( 980 ) which is located closely to the K K ¯ threshold and has a suppressed decay into the lighter ππ channel.
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Testing the $\chi_{c1}\, p$ Composite Nature of the $P_c(4450)$
arXiv: High Energy Physics - Phenomenology, 2015Co-Authors: Ulf-g. Meißner, J A OllerAbstract:Making use of a recently proposed formalism, we analyze the Composite Nature of the $P_c(4450)$ resonance observed by LHCb. We show that the present data suggest that this state is almost entirely made of a $\chi_{c1}$ and a proton, due to the close proximity to this threshold. This also suppresses the decay modes into other, lighter channels, in our study represented by $J/\Psi p$. We further argue that this is very similar to the case of the scalar meson $f_0(980)$ which is located closely to the $K\bar K$ threshold and has a suppressed decay into the lighter $\pi\pi$ channel.
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testing the chi_ c1 p Composite Nature of the p_c 4450
arXiv: High Energy Physics - Phenomenology, 2015Co-Authors: Ulfg Meisner, J A OllerAbstract:Making use of a recently proposed formalism, we analyze the Composite Nature of the $P_c(4450)$ resonance observed by LHCb. We show that the present data suggest that this state is almost entirely made of a $\chi_{c1}$ and a proton, due to the close proximity to this threshold. This also suppresses the decay modes into other, lighter channels, in our study represented by $J/\Psi p$. We further argue that this is very similar to the case of the scalar meson $f_0(980)$ which is located closely to the $K\bar K$ threshold and has a suppressed decay into the lighter $\pi\pi$ channel.