Research progress on refractory composition and deformability of shell molds for TiAl alloy castings

At present, most TiAl components are produced by an investment casting process. Environmental and economic pressures have, however, resulted in a need for the industry to improve the current casting quality, reduce manufacturing costs and explore new markets for the process. Currently, the main problems for investment casting of TiAl alloys are cracks, porosities, and surface defects. To solve these problems, many studies have been conducted around the world, and it is found that casting defects can be reduced by improving composition and properties of the shell molds. It is important to make a summary for the related research progress for quality improvement of TiAl castings. So, the development on refractory composition of shell molds for TiAl alloy investment castings was reviewed, and research progress on deformability of shell mold for TiAl alloy castings both at home and abroad in recent years was introduced. The existing methods for deformability characterization and methods for improving the deformability of shell molds were summarized and discussed. The updated advancement in numerical simulation of TiAl alloy investment casting was presented, showing the necessity for considering the deformability of shell mold during simulation. Finally, possible research points for future studies on deformability of shell mold for TiAl alloy investment casting were proposed.

Deformability and microstructure transformation of PM TiAl alloy prepared by pseudo-HIP technology

Microstructures and deformation properties of Ti-46Al-(Cr,Nb,W,B)alloy consolidated by pseudo-HIP technology were investigated.The results show that the pseudo-HIP temperature has a significant effect on microstructures.When the sintering temperature is 1 100℃,the microstructure of as-pseudo-HIPped alloy is similar to that of the prealloyed powder and the interfaces of these powder particles are still discernible,but a nearγmicrostructure appears in particles.Increasing the pressing temperature to 1 200℃develops successfully a homogeneous and fine-grained duplex microstructure.A typically fully lamellar microstructure with residualβphase is developed at 1 300℃.The compact exhibits excellent deformation properties at elevated temperatures. When the compression temperature is higher than 1 100℃,high quality products without cracks can be obtained even if the engineering compression strain is up to 0.8 at strain rates of 10-2-10-3s-1.It can be established that the mechanical twinning and matrix deformation due to ordinary dislocation slip/climb contribute to the whole hot deformation.

Super deformability and thermoelectricity of bulkγ-InSe single crystals

Indium selenide,aⅢ–Ⅴgroup semiconductor with layered structure,attracts intense attention in various photoelectric applications,due to its outstanding properties.Here,we report super deformability and thermoelectricity ofγ-In Se single crystals grown by modified Bridgeman method.The crystal structure of In Se is studied systematically by transmission electron microscopy methods combined with x-ray diffraction and Raman spectroscopy.The predominate phase ofγ-In Se with dense stacking faults and local multiphases is directly demonstrated at atomic scale.The bulkγ-In Se crystals demonstrate surprisingly high intrinsic super deformative ability which is highly pliable with bending strains exceeding12.5%and 264%extension by rolling.At the meantime,In Se also possesses graphite-like features which is printable,writable,and erasable.Finally,the thermoelectric properties ofγ-In Se bulk single crystals are preliminary studied and thermal conductivity can be further reduced via bending-induced defects.These findings will enrich the knowledge of structural and mechanical properties'flexibility of In Se and shed lights on the intrinsic and unique mechanical properties of In Se polytypes.

Prediction of strength and deformability of an interlocked blocky rock mass using UDEC

The accurate prediction of strength and deformability characteristics of rock mass is a challenging issue.In practice,properties of a rock mass are often estimated from available empirical relationships based on the uniaxial compressive strength(UCS).However,UCS does not always give a good indication of in situ rock mass strength and deformability.The aim of this paper is to present a methodology to predict the strength and deformability of a jointed rock mass using UDEC(universal distinct element code).In the study,the rock mass is modelled as an assemblage of deformable blocks that can yield as an intact material and/or slide along predefined joints within the rock mass.A range of numerical simulations of uniaxial and triaxial tests was conducted on rock mass samples in order to predict the equivalent mechanical properties for the rock mass under different loading directions.Finally,results are compared with the deformability parameters obtained by analytical methods.

Numerical evaluation of strength and deformability of fractured rocks

Knowledge of the strength and deformability of fractured rocks is important for design, construction and stability evaluation of slopes, foundations and underground excavations in civil and mining engineering. However, laboratory tests of intact rock samples cannot provide information about the strength and deformation behaviors of fractured rock masses that include many fractures of varying sizes, orientations and locations. On the other hand, large-scale in situ tests of fractured rock masses are economically costly and often not practical in reality at present. Therefore, numerical modeling becomes necessary. Numerical predicting using discrete element methods(DEM) is a suitable approach for such modeling because of their advantages of explicit representations of both fractures system geometry and their constitutive behaviors of fractures, besides that of intact rock matrix. In this study, to generically determine the compressive strength of fractured rock masses, a series of numerical experiments were performed on two-dimensional discrete fracture network models based on the realistic geometrical and mechanical data of fracture systems from feld mapping. We used the UDEC code and a numerical servo-controlled program for controlling the progressive compressive loading process to avoid sudden violent failure of the models. The two loading conditions applied are similar to the standard laboratory testing for intact rock samples in order to check possible differences caused by such loading conditions. Numerical results show that the strength of fractured rocks increases with the increasing confning pressure, and that deformation behavior of fractured rocks follows elasto-plastic model with a trend of strain hardening. The stresses and strains obtained from these numerical experiments were used to ft the well-known Mohr-Coulomb(MC) and Hoek-Brown(H-B) failure criteria, represented by equivalent material properties defning these two criteria. The results show that both criteria can provide fair estimates of the compressive strengths for all tested numerical models. Parameters of the elastic deformability of fractured models during elastic deformation stages were also evaluated, and represented as equivalent Young’s modulus and Poisson’s ratio as functions of lateral confning pressure. It is the frst time that such systematic numerical predicting for strength of fractured rocks was performed considering different loading conditions, with important fndings for different behaviors of fractured rock masses, compared with testing intact rock samples under similar loading conditions.

Symmetry energy of strange quark matter and tidal deformability of strange quark stars

Research performed during the past decade revealed an important role of symmetry energy in the equation of state(EOS)of strange quark matter(SQM).By introducing an isospin-dependent term into the quark mass scaling,the SQM stability window in the equivparticle model was studied.The results show that a sufficiently strong isospin dependence C_(I)can significantly widen the SQM region of absolute stability,yielding results that simultaneously satisfy the constraints of the astrophysical observations of PSR J1614-2230 with 1.928±0.017 Mand tidal deformability 70≤Λ_(1:4)≤580 measured in the event GW170817.With increasing C_(I),the difference between the u,d,and s quark fractions for the SQM inβ-equilibrium becomes inconspicuous for C>0,leading to small isospin asymmetryδ,and further resulting in similar EOS and structures of strange quark stars(SQSs).Moreover,unlike the behavior of the maximum mass of ud QSs,which varies with C_(I)depending on the sign of the parameter C,the maximum mass of the SQSs decreases monotonously with increasing CI.

Influence of hot isostatic pressing on microstructure,properties and deformability of selective laser melting TC4 alloy

The influence of different hot isostatic pressing regimes on microstructure,phase constitution,microhardness,tensile properties and deformability of TC4 alloy fabricated by selective laser melting(SLM)technology was studied.The results show that the microstructure of SLM TC4 alloy is composed of acicular martensiteα’phase,and the sample exhibits high microhardness and strength,but low plasticity.After hot isostatic pressing,acicular martensiteα’phase transforms intoα+βphase,and with the increase of hot isostatic pressing temperature and duration,αphase with coarse lath is gradually refined,and the proportion ofαphase is gradually reduced.Because of the change of phase constitution in SLM TC4 alloy after hot isostatic pressing,the grain refinement strengthening is weakened,the density of dislocation is reduced,so that both microhardness and tensile strength are decreased by around 20%,the elongation is increased by more than about 70%,even over 100%,compared with as-deposited TC4 alloy.When the hot isostatic pressing regime is 940°C/3 h/150 MPa,the tensile strength and the elongation achieve optimal match,which are about890 MPa and around 14.0%in both directions.The fracture mechanism of alloy after 940 oC/3 h/150 MPa HIP is dultile fracture.Hot isostatic pressing causes concave deformation of SLM TC4 alloy thin-walled frames,and the deformation degree increases with the increase of temperature.

Effects of estrogen and androgen level on erythrocyte deformability in endocrinological erectile dysfunction

Objective: To evaluate the effect of estrogen and androgen levels on erythrocyte deformability in endocrinological erectile dysfunction patients. Methods: The estrogen level, androgen level, IR of 30 psychogenic and 15 endocriological ED were studied and the correlation between the estrogen and androgen levels and RI were analyzed. Results: There is a negative correlation betweenthe androgen and estrogen levels and IR; The IR (5.9033 ± 1.9369), η_(10)(11.2810 ± 1.3120) values in the endcocrinological group were markedly higher than those (4.0589 ± 1.55339, 9.8321 ± 1.6415) in the psychogenic group. Conclusion: The lower level of the estrogen and androgen in endocrinological ED patients may result in the decrease of erythrocyte deformability causing the increase in blood viscosity. To enhance in time the levels of estrogen and androgen might improve penile erectile function of endocrinological ED patients in hemodynamics

THE CHANGES OF DEFORMABILITY OF ERYTHROCYTES AND 2.3-DPG IN RED BLOOD CELL AND BLOOD IN PATIENTS WITH CORONARY ARTERY STENOSIS

The purpose of this paper is to study the changes of deformabilityof erythrocytes and 2.3-DPG(2.3-diphosphoglycerate acid)in the patients with coro-nary artery stenosis and the effects of some factors on them.It is showed that:de-formability of crythrocyte and 2.3-DPG were inversely proportional to the degreeof the lesions of coronary vessels(P【0.01);there was a significant decrease of de-formability of erythrocytes after using contract agents(P【0.01);Salvia increaseddeformability and 2.3-DPG significantly(P【0.01).In conclusion,our data suggestthat the possible existence of microcirculation dysfunction in coronary artery dis-eases with parallelism to the impairement deformability of erythrocytcs and Salviabca good drug to action in deformability and 2.3 DPG in patients.

Enhancing plastic deformability of Mg and its alloys—A review of traditional and nascent developments

Mg and its alloys have continued to attract interest for several structural and super-sensitive applications because of their light weight and good combination of engineering properties.However for some of these applications,high plastic deformability is required to achieve desired component shapes and configurations;unfortunately,Mg and its alloys have low formability.Scientifically,the plastic behaviour of Mg and its alloys ranks among the most complex and difficult to reconcile in metallic material systems.But basically,the HCP crystal structure coupled with low stacking fault energies(SFE)are largely linked to the poor ductility exhibited by Mg alloys.These innate material characteristics have regrettably limited wide spread applicability of Mg and its alloys.Several research efforts aimed at exploring processing strategies to make these alloys more amenable for high formability–mediated engineering use have been reported and still ongoing.This paper reviews the structural metallurgy of Mg alloys and its influence on mechanical behaviour,specifically,plasticity characteristics.It also concisely presents various processing routes(Alloying,Traditional Forming and Severe Plastic Deformation(SPD))which have been explored to enhance plastic deformability in Mg and its alloys.Grain refinement and homogenising of phases,reducing CRSS between slip modes,twinning suppression to activate non-basal slip,and weakening and randomisation of the basal texture were observed as the formability enhancing strategies explored in the reviewed processes.While identifying the limitations of these strategies,further areas to be explored for enhancing plasticity of Mg alloys are highlighted.

Mechanisms of Improvement of High Temperature Deformability of Ti-43Al-9V-0.3Y Alloy with Addition of Y

The effects of yttrium additions on plastic deformability and the change of microstructures after deformation of TiAl alloys were investigated by hot-compression pressing. The compositions studied are Ti-43Al-9V (%) and Ti-43Al-9V-0.3Y (%). Before the hot-compression, all the samples were homogenized at 900 ℃ for 48 h and treated by hot isostatic pressing at 1250 ℃ for 4 h under an argon pressure of 170 MPa. The hot-compression experiments were conducted with the Gleeble-1500D style of thermo-force analogue machine at the temperatures of 1100, 1150, 1200 ℃ and strain rates of 1.0, 0.1, 0.01 s^(-1). The results show that the addition of yttrium can remarkably improve hot-compression deformability of Ti-43Al-9V alloy. Analysisically, main reasons for the improvement are that Ti-43Al-9V-0.3Y alloy possesses some characteristics, such as smaller grain size, lower resistance of deformation and deformation activation energy, and faster recrystallization and smaller homogeneous recrystallized grains.

Anisotropy of strength and deformability of fractured rocks

Anisotropy of the strength and deformation behaviors of fractured rock masses is a crucial issue for design and stability assessments of rock engineering structures, due mainly to the non-uniform and non- regular geometries of the fracture systems. However, no adequate efforts have been made to study this issue due to the current practical impossibility of laboratory tests with samples of large volumes con- taining many fractures, and the difficulty for controlling reliable initial and boundary conditions for large-scale in situ tests. Therefore, a reliable numerical predicting approach for evaluating anisotropy of fractured rock masses is needed. The objective of this study is to systematically investigate anisotropy of strength and deformability of fractured rocks, which has not been conducted in the past, using a nu- merical modeling method. A series of realistic two-dimensional （2D） discrete fracture network （DFN） models were established based on site investigation data, which were then loaded in different directions, using the code UDEC of discrete element method （DEM）, with changing confining pressures. Numerical results show that strength envelopes and elastic deformability parameters of tested numerical models are significantly anisotropic, and vary with changing axial loading and confining pressures. The results indicate that for design and safety assessments of rock engineering projects, the directional variations of strength and deformability of the fractured rock mass concerned must be treated properly with respect to the directions of in situ stresses. Traditional practice for simply positioning axial orientation of tunnels in association with principal stress directions only may not be adequate for safety requirements. Outstanding issues of the present study and su^zestions for future study are also oresented.

Dependence of the tidal deformability of neutron stars on the nuclear equation of state

Within the Bayesian framework,using an explicitly isospin-dependent parametric equation of state(EOS)for the core of neutron stars(NSs),we studied how the NS EOS behaves when we confront it with the tidal deformabilitiesΛ1.4abilities of massive NSs.We found that it does not significantly improve the constraints on the NS EOS but has a weak effect on narrowing down the slope parameter of the symmetry energy by decreasing the measurement errors ofΛ1.4.Both the isospin-dependent and isospin-independent parts of the NS EOS were significantly constrained and raised as the tidal deformabilities of massive NSs were adopted in the calculations,especially in high-density regions.We also found thatΛ1.4symmetry energy,whereas the opposite occurs for the radius of canonical NSs R1.4.The tidal deformability of an NS with two times the solar massΛ2.0ergy,andΛ1.4and R1.4have no correlation with the former.

Evolution and deformability of inclusions in Al-killed steel with rare earth-alkali metals(Ca or Mg) combined treatment

The quality of stainless steel is closely related to the deformability of inclusions,which is significantly affected by their compositions.The present study first inve stigated the evolution of inclusion compositions in AI-killed steel with rare earth-alkali metals(Ca or Mg)combined treatme nt through four laboratory-scale experiments.The Ce contents in the final steel are 0.0080 wt%,0.015 wt%,0.016 wt%and 0.010 wt%,respectively.The Mg content is 0.0014 wt%in Ce-Mg combined treated steel,and the Ca content is0.0015 wt%in Ce-Ca combined treated steel.The deformability of inclusions in both Ce_(2)O_(3)-Al_(2)O_(3)-CaO and Ce_(2)O_(3)-Al_(2)O_(3)-MgO systems was subsequently evaluated by calculating their Young's modulus at low temperature.The results show that irregular Al_(2)O_(3)and MgAl_(2)O_(4)with poor deformability are modified to CeAlO_(3)and Ce_(2)O_(3)by Ce treatment,resulting in the decrease of Young's modulus of inclusions.The deformability of inclusions is further improved due to the transformation from lumped-like CeAlO_(3)to spherical CaO-Al_(2)O_(3)-Ce_(2)O_(3)caused by Ca treatment,and some of these inclusions are the ones with low liquidus temperature.Thermodynamic analysis was used to discuss the control condition of the formation and evolution of inclusions.Accordingly,the appropriate addition amounts of Al,Mg,Ce,and Ca are expected to control inclusion compositions and properties,including deformability and liquidus temperature,thereby improving the steel performance.

A deformability-based biochip for precise label-free stratification of metastatic subtypes using deep learning

Cellular deformability is a promising biomarker for evaluating the physiological state of cells in medical applications.Microfluidics has emerged as a powerful technique for measuring cellular deformability.However,existing microfluidic-based assays for measuring cellular deformability rely heavily on image analysis,which can limit their scalability for high-throughput applications.Here,we develop a parallel constriction-based microfluidic flow cytometry device and an integrated computational framework(ATMQcD).The ATMQcD framework includes automatic training set generation,multiple object tracking,segmentation,and cellular deformability quantification.The system was validated using cancer cell lines of varying metastatic potential,achieving a classification accuracy of 92.4%for invasiveness assessment and stratifying cancer cells before and after hypoxia treatment.The ATMQcD system also demonstrated excellent performance in distinguishing cancer cells from leukocytes(accuracy=89.5%).We developed a mechanical model based on power-law rheology to quantify stiffness,which was fitted with measured data directly.The model evaluated metastatic potentials for multiple cancer types and mixed cell populations,even under realworld clinical conditions.Our study presents a highly robust and transferable computational framework for multiobject tracking and deformation measurement tasks in microfluidics.We believe that this platform has the potential to pave the way for high-throughput analysis in clinical applications,providing a powerful tool for evaluating cellular deformability and assessing the physiological state of cells.

7075铝合金切削加工晶粒尺寸演化过程研究

金属材料在切削加工过程中,表层晶粒在机械载荷和热载荷的剧烈冲击作用下快速再结晶使表面形成晶粒细化层,该细化层严重影响材料使役性能。在研究切削加工晶粒尺寸演化机制的基础上,通过DEFORM仿真软件实现7075铝合金晶粒尺寸演化过程,开展单因素法试验,构建了晶粒尺寸关于切削速度、进给量的预测模型。结果表明:切削速度增加,表层晶粒尺寸增大,细化层厚度减小;进给量增加,晶粒尺寸和细化层厚度在温度和塑性变形共同作用下先增加后减小。通过实验验证,该模型能够较为准确地预测材料表面晶粒尺寸。

基于改进Deformable DETR的无人机视频流车辆目标检测算法

针对无人机视频流检测中小目标数量多、因图像传输质量较低而导致的上下文语义信息不充分、传统算法融合特征推理速度慢、数据集类别样本不均衡导致的训练效果差等问题,提出一种基于改进Deformable DETR的无人机视频流车辆目标检测算法。在模型结构方面,该算法设计了跨尺度特征融合模块以增大感受野,提升小目标检测能力,并采用针对object_query的挤压-激励模块提升关键目标的响应值,减少重要目标的漏检与错检率;在数据处理方面,使用了在线困难样本挖掘技术,改善数据集中类别样本分布不均的问题。在UAVDT数据集上进行了实验,实验结果表明,改进后的算法相较于基线算法在平均检测精度上提升了1.5%,在小目标检测精度上提升了0.8%,并在保持参数量较少增长的情况下,维持了原有的检测速度。

Mechanical Modeling and Analysis of Stability Deterioration of Production Well During Marine Hydrate Depressurization Production

Different from oil and gas production,hydrate reservoirs are shallow and unconsolidated,whose mechanical properties deteriorate with hydrate decomposition.Therefore,the formations will undergo significant subsidence during depressurization,which will destroy the original force state of the production well.However,existing research on the stability of oil and gas production wells assumes the formation to be stable,and lacks consideration of the force exerted on the hydrate production well by formation subsidence caused by hydrate decomposition during production.To fill this gap,this paper proposes an analytical method for the dynamic evolution of the stability of hydrate production well considering the effects of hydrate decomposition.Based on the mechanical model of the production well,the basis for stability analysis has been proposed.A multi-field coupling model of the force state of the production well considering the effect of hydrate decomposition and formation subsidence is established,and a solver is developed.The analytical approach is verified by its good agreement with the results from the numerical method.A case study found that the decomposition of hydrate will increase the pulling-down force and reduce the supporting force,which is the main reason for the stability deterioration.The higher the initial hydrate saturation,the larger the reservoir thickness,and the lower the production pressure,the worse the stability or even instability.This work can provide a theoretical reference for the stability maintaining of the production well.

Application of GNSS-PPP on Dynamic Deformation Monitoring of Offshore Platforms

The real-time dynamic deformation monitoring of offshore platforms under environmental excitation is crucial to their safe operation.Although Global Navigation Satellite System-Precise Point Positioning(GNSS-PPP)has been considered for this purpose,its monitoring accuracy is relatively low.Moreover,the influence of background noise on the dynamic monitoring accuracy of GNSS-PPP remains unclear.Hence,it is imperative to further validate the feasibility of GNSS-PPP for deformation monitoring of offshore platforms.To address these concerns,vibration table tests with different amplitudes and frequencies are conducted.The results demonstrate that GNSS-PPP can effectively monitor horizontal vibration displacement as low as±30 mm,which is consistent with GNSS-RTK.Furthermore,the spectral characteristic of background noise in GNSS-PPP is similar to that of GNSS-RTK(Real Time Kinematic).Building on this observation,an improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)has been proposed to de-noise the data and enhance the dynamic monitoring accuracy of GNSS-PPP.Field monitoring application research is also undertaken,successfully extracting and analyzing the dynamic deformation of an offshore platform structure under environmental excitation using GNSS-PPP monitoring in conjunction with improved CEEMDAN de-noising.By comparing the de-noised dynamic deformation trajectories of the offshore platform during different periods,it is observed that the platform exhibits reversible alternating vibration responses under environmental excitation,with more pronounced displacement deformation in the direction of load action.The research results confirm the feasibility and potential of GNSS-PPP for dynamic deformation monitoring of offshore platforms.

Deformable Catalytic Material Derived from Mechanical Flexibility for Hydrogen Evolution Reaction

Deformable catalytic material with excellent flexible structure is a new type of catalyst that has been applied in various chemical reactions,especially electrocatalytic hydrogen evolution reaction(HER).In recent years,deformable catalysts for HER have made great progress and would become a research hotspot.The catalytic activities of deformable catalysts could be adjustable by the strain engineering and surface reconfiguration.The surface curvature of flexible catalytic materials is closely related to the electrocatalytic HER properties.Here,firstly,we systematically summarized self-adaptive catalytic performance of deformable catalysts and various micro–nanostructures evolution in catalytic HER process.Secondly,a series of strategies to design highly active catalysts based on the mechanical flexibility of lowdimensional nanomaterials were summarized.Last but not least,we presented the challenges and prospects of the study of flexible and deformable micro–nanostructures of electrocatalysts,which would further deepen the understanding of catalytic mechanisms of deformable HER catalyst.