The effect of adding a small amount of Ag on the microstructure evolution and superplastic properties of Mg-Y-Er-Zn(WEZ612) alloys was systematically studied.The basal texture of the refined WEZ612 alloy produced by e...The effect of adding a small amount of Ag on the microstructure evolution and superplastic properties of Mg-Y-Er-Zn(WEZ612) alloys was systematically studied.The basal texture of the refined WEZ612 alloy produced by equal channel angular pressing was altered to a non-basal structure upon the addition of Ag.Ag addition also refined the grain size and promoted the formation of a large number of nano-14H-long period stacking ordered phases.Using high-resolution transmission electron microscopy,many nano-precipitated phases were detected on the basal plane of the Mg-Y-Er-Zn-1Ag(WEZ612-1Ag) alloy,The nano-precipitated phases on the basal plane improved the thermal stability of the alloy,lowered the deformation activation energy(Q),and improved the stress sensitivity index(m).At 523 K with a strain rate of 10^(-2) s^(-1),the Q value of WEZ612 was higher than that of WEZ612-1Ag(299.14 and 128.5 kJ mol^(-1),respectively).In contrast,the m value of the WEZ612 alloy(0.16) was lower than that of the WEZ612-1Ag alloy(0.46).At 623 K with a tensile rate of 10^(-2) s^(-1),the WEZ612 and WEZ612-1Ag alloys were elongated by 182% and 495%,respectively,with the latter exhibiting high-strain-rate and low-temperature superplasticity.The improved superplasticity of the WEZ612-1Ag alloy is attributed to the nano-precipitated phases,which effectively limit the cavity extension during superplastic deformation.展开更多
In 2010, the fracking discussion in Germany caused a number of changes in German law, which came into force in 2016.Especially the production of gas had to be regulated.With the legislation amendment, the Subsidence-A...In 2010, the fracking discussion in Germany caused a number of changes in German law, which came into force in 2016.Especially the production of gas had to be regulated.With the legislation amendment, the Subsidence-Area Mining Regulation has been revised, too.The changes expand the compensation of mining damages, especially to the extraction with drilling from the surface and underground storage.Although the Subsidence-Area Mining Regulation has been revised, the area of main influence(subsidence of 10 cm)remains to determine a relevant boundary for mining damages.The determination and prediction of this boundary above caverns are presented in this paper.In addition, further elements of ground movements and their relevance to mine damages are analyzed.The usage of the area of main influence to fix a relevant boundary for mining damages does not correspond to the relevant elements of ground movements.A limit for differences in subsidence(tilt) or horizontal changes in length should be preferred to describe the relevance of mining damages on buildings.Furthermore, this paper outlines the meaning of using the area of main influence to fix a relevant boundary for mining damages.展开更多
High-throughput computational materials design is an emerging area in materials science,which is based on the fast evaluation of physical-related properties.The lattice thermal conductivity(κ)is a key property of mat...High-throughput computational materials design is an emerging area in materials science,which is based on the fast evaluation of physical-related properties.The lattice thermal conductivity(κ)is a key property of materials for enormous implications.However,the high-throughput evaluation ofκremains a challenge due to the large resources costs and time-consuming procedures.In this paper,we propose a concise strategy to efficiently accelerate the evaluation process of obtaining accurate and convergedκ.The strategy is in the framework of phonon Boltzmann transport equation(BTE)coupled with first-principles calculations.Based on the analysis of harmonic interatomic force constants(IFCs),the large enough cutoff radius(r^(cutoff)),a critical parameter involved in calculating the anharmonic IFCs,can be directly determined to get satisfactory results.Moreover,we find a simple way to largely(~10 times)accelerate the computations by fast reconstructing the anharmonic IFCs in the convergence test ofκwith respect to the rcutof,which finally confirms the chosen r^(cutoff) is appropriate.Two-dimensional graphene and phosphorene along with bulk SnSe are presented to validate our approach,and the long-debate divergence problem of thermal conductivity in low-dimensional systems is studied.The quantitative strategy proposed herein can be a good candidate for fast evaluating the reliableκand thus provides useful tool for high-throughput materials screening and design with targeted thermal transport properties.展开更多
Phosphorene, a two-dimensional （2D） elemen- tal semiconductor with a high carrier mobility and intrinsic direct band gap, possesses fascinating chemical and physical properties distinctively different from other 2D ...Phosphorene, a two-dimensional （2D） elemen- tal semiconductor with a high carrier mobility and intrinsic direct band gap, possesses fascinating chemical and physical properties distinctively different from other 2D materials. Its rapidly growing applications in nano-/opto- electronics and thermoelectrics call for fundamental understanding of the thermal transport properties. Con- sidering the fact that there have been so many studies on the thermal transport in phosphorene, it is on emerging demand to have a review on the progress of previous studies and give an outlook on future work. In this mini- review, the unique thermal transport properties of phos- phorene induced by the hinge-like structure are examined. There exists a huge deviation in the reported thermal conductivity of phosphorene in literature. Besides, the mechanism underlying the deviation is discussed by reviewing the effect of different functionals and cutoff distance in calculating the thermal transport properties of phosphorene. It is found that the van der Waals （vdW） interactions play a key role in the formation of resonant bonding, which leads to long-ranged interactions. Taking into account of the vdW interactions and including the long-ranged interactions caused by the resonant bonding with large cutoff distance are important for getting the accurate and converged thermal conductivity of phosphor- ene. Moreover, a fundamental insight into the thermal transport is provided based on the review of resonant bonding in phosphorene. This mini-review summarizes theprogress of the thermal transport in phosphorene and gives an outlook on future horizons, which would benefit the design of phosphorene based nano-electronics.展开更多
基金supported by the Postgraduate Research and Practice Innovation Program of Jiangsu Province (SJKY19_0460)the National Natural Science Foundation of China (Grant No.51979099 & 51774109)+2 种基金Natural Science Foundation of Jiangsu Province of China (Grant No.BK20191303)The Key Research and Development Project of Jiangsu Province of China (Grant No.BE2017148)Postgraduate Education Reform Project of Jiangsu Province (JGLX19_027)。
文摘The effect of adding a small amount of Ag on the microstructure evolution and superplastic properties of Mg-Y-Er-Zn(WEZ612) alloys was systematically studied.The basal texture of the refined WEZ612 alloy produced by equal channel angular pressing was altered to a non-basal structure upon the addition of Ag.Ag addition also refined the grain size and promoted the formation of a large number of nano-14H-long period stacking ordered phases.Using high-resolution transmission electron microscopy,many nano-precipitated phases were detected on the basal plane of the Mg-Y-Er-Zn-1Ag(WEZ612-1Ag) alloy,The nano-precipitated phases on the basal plane improved the thermal stability of the alloy,lowered the deformation activation energy(Q),and improved the stress sensitivity index(m).At 523 K with a strain rate of 10^(-2) s^(-1),the Q value of WEZ612 was higher than that of WEZ612-1Ag(299.14 and 128.5 kJ mol^(-1),respectively).In contrast,the m value of the WEZ612 alloy(0.16) was lower than that of the WEZ612-1Ag alloy(0.46).At 623 K with a tensile rate of 10^(-2) s^(-1),the WEZ612 and WEZ612-1Ag alloys were elongated by 182% and 495%,respectively,with the latter exhibiting high-strain-rate and low-temperature superplasticity.The improved superplasticity of the WEZ612-1Ag alloy is attributed to the nano-precipitated phases,which effectively limit the cavity extension during superplastic deformation.
文摘In 2010, the fracking discussion in Germany caused a number of changes in German law, which came into force in 2016.Especially the production of gas had to be regulated.With the legislation amendment, the Subsidence-Area Mining Regulation has been revised, too.The changes expand the compensation of mining damages, especially to the extraction with drilling from the surface and underground storage.Although the Subsidence-Area Mining Regulation has been revised, the area of main influence(subsidence of 10 cm)remains to determine a relevant boundary for mining damages.The determination and prediction of this boundary above caverns are presented in this paper.In addition, further elements of ground movements and their relevance to mine damages are analyzed.The usage of the area of main influence to fix a relevant boundary for mining damages does not correspond to the relevant elements of ground movements.A limit for differences in subsidence(tilt) or horizontal changes in length should be preferred to describe the relevance of mining damages on buildings.Furthermore, this paper outlines the meaning of using the area of main influence to fix a relevant boundary for mining damages.
基金This work is supported by the Deutsche Forschungsgemeinschaft(DFG)(Project number:HU 2269/2-1).
文摘High-throughput computational materials design is an emerging area in materials science,which is based on the fast evaluation of physical-related properties.The lattice thermal conductivity(κ)is a key property of materials for enormous implications.However,the high-throughput evaluation ofκremains a challenge due to the large resources costs and time-consuming procedures.In this paper,we propose a concise strategy to efficiently accelerate the evaluation process of obtaining accurate and convergedκ.The strategy is in the framework of phonon Boltzmann transport equation(BTE)coupled with first-principles calculations.Based on the analysis of harmonic interatomic force constants(IFCs),the large enough cutoff radius(r^(cutoff)),a critical parameter involved in calculating the anharmonic IFCs,can be directly determined to get satisfactory results.Moreover,we find a simple way to largely(~10 times)accelerate the computations by fast reconstructing the anharmonic IFCs in the convergence test ofκwith respect to the rcutof,which finally confirms the chosen r^(cutoff) is appropriate.Two-dimensional graphene and phosphorene along with bulk SnSe are presented to validate our approach,and the long-debate divergence problem of thermal conductivity in low-dimensional systems is studied.The quantitative strategy proposed herein can be a good candidate for fast evaluating the reliableκand thus provides useful tool for high-throughput materials screening and design with targeted thermal transport properties.
文摘Phosphorene, a two-dimensional （2D） elemen- tal semiconductor with a high carrier mobility and intrinsic direct band gap, possesses fascinating chemical and physical properties distinctively different from other 2D materials. Its rapidly growing applications in nano-/opto- electronics and thermoelectrics call for fundamental understanding of the thermal transport properties. Con- sidering the fact that there have been so many studies on the thermal transport in phosphorene, it is on emerging demand to have a review on the progress of previous studies and give an outlook on future work. In this mini- review, the unique thermal transport properties of phos- phorene induced by the hinge-like structure are examined. There exists a huge deviation in the reported thermal conductivity of phosphorene in literature. Besides, the mechanism underlying the deviation is discussed by reviewing the effect of different functionals and cutoff distance in calculating the thermal transport properties of phosphorene. It is found that the van der Waals （vdW） interactions play a key role in the formation of resonant bonding, which leads to long-ranged interactions. Taking into account of the vdW interactions and including the long-ranged interactions caused by the resonant bonding with large cutoff distance are important for getting the accurate and converged thermal conductivity of phosphor- ene. Moreover, a fundamental insight into the thermal transport is provided based on the review of resonant bonding in phosphorene. This mini-review summarizes theprogress of the thermal transport in phosphorene and gives an outlook on future horizons, which would benefit the design of phosphorene based nano-electronics.
