Pressure generation under deformation in a large-volume press

Deformation can change the transition pathway of materials under high pressure,thus significantly affects physical and chemical properties of matters.However,accurate pressure calibration under deformation is challenging and thereby causes relatively large pressure uncertainties in deformation experiments,resulting in the synthesis of complex multiphase materials.Here,pressure generations of three types of deformation assemblies were well calibrated in a Walker-type largevolume press(LVP)by electrical resistance measurements combined with finite element simulations(FESs).Hard Al_(2)O_(3) or diamond pistons in shear and uniaxial deformation assemblies significantly increase the efficiency of pressure generation compared with the conventional quasi-hydrostatic assembly.The uniaxial deformation assembly using flat diamond pistons possesses the highest efficiency in these deformation assemblies.This finding is further confirmed by stress distribution analysis based on FESs.With this deformation assembly,we found shear can effectively promote the transformation of C60 into diamond under high pressure and realized the synthesis of phase-pure diamond at relatively moderate pressure and temperature conditions.The present developed techniques will help improve pressure efficiencies in LVP and explore the new physical and chemical properties of materials under deformation in both science and technology.

Function of large-volume high-pressure apparatus at SECUF

Pressure allows the precise tuning of a fundamental parameter, the interatomic distance, which controls the electronic structure and virtually all interatomic interactions that determine material properties. Hence, pressure tuning is an effective tool in the search for new materials with enhanced properties. To realize pressure tuning on matter, large-volume press （LVP） apparatuses have been widely used not only to synthesize novel materials but also to implement the in situ measurement of physical properties. Herein, we introduce the LVP apparatuses, including belt-type, cubic anvil, and 6-8 type multi-anvil, that will be constructed at the Synergetic Extreme Condition User Facility （SECUF） at Jilin University. Typically, cell volumes of 1000 mm3 can be obtained at 20 GPa in a belt-type apparatus that is significantly larger than that obtained in a 6-8 type multi-anvil apparatus at the same pressure. Furthermore, the in situ measurement of physical prop- erties, including thermological, electrical, and mechanical behaviors, is coupled to these LVP apparatuses. Some typical results of both synthetic experiments and in situ measurements obtained from the LVP apparatuses are also reviewed.

IPS e.max Press铸瓷与合金嵌体治疗后牙牙体缺损效果对比研究

目的探讨IPS e.max Press铸瓷与合金嵌体治疗后牙牙体缺损的效果。方法前瞻性纳入2020-05—2022-05三门峡市中心医院口腔科收治的后牙牙体缺损患者,根据修复材料分为IPS e.max Press铸瓷嵌体组(铸瓷组)和合金嵌体组(合金组)。比较2组患者的基线资料。治疗前后检测患者的龈沟液中炎性因子、评价牙周健康情况。治疗3个月后评价牙体缺损边缘密合度和美牙效果。结果共纳入86例(132颗牙)患者,每组43例(66颗牙)。2组患者的基线资料差异无统计学意义(P>0.05)。治疗后铸瓷组患者的IL-6、IL-8、CXCL16水平和GI、SBI及PLI评分均低于合金组;牙体缺损边缘密合度优于合金组,美牙效果满意率高于合金组。差异均有统计学意义(P<0.05)。结论与合金嵌体比较,采用IPS e.max Press铸瓷嵌体治疗后牙牙体缺损有利于降低龈沟液中炎性因子水平,改善牙周健康状况和牙体缺损边缘密合度,并可提高患者对美牙效果的满意度。但仍需进行更大样本量的前瞻性随机对照研究予以证实。

IPS e.max press热压铸造陶瓷全冠及二氧化锆全瓷冠对前牙修复患者牙龈健康美观度的影响

目的:比较IPS e.max press热压铸造陶瓷全冠及二氧化锆全瓷冠对前牙修复患者牙龈健康、美观度的影响,为前牙美学修复的材料选择提供临床参考。方法:以2021年5月至2022年5月于我院接受前牙修复的104例患者为研究对象,以随机数字表法分为两组,分别52例。观察组、对照组分别以IPS e.max press铸瓷全冠、二氧化锆全瓷冠修复,比较两组患者的临床修复效果及修复后的牙龈指数、菌斑指数、龈沟出血指数、龈沟液炎性因子水平。结果:观察组边缘密合度、继发龋情况均优于对照组(P<0.05);修复后,观察组牙龈指数、菌斑指数等显著小于对照组,龈沟液IL-6、IL-8及TNF-α水平显著低于对照组(P<0.05);修复12个月后,观察组PES评分高于对照组(P<0.05)。结论:相比于二氧化锆全瓷冠,IPS e.max press铸瓷全冠具有良好的前牙美学修复效果,可降低龈沟液炎性因子水平,改善牙龈健康,并能提高前牙美观度。

Neutron Diffraction of Large-Volume Samples at High Pressure Using Compact Opposed-Anvil Cells

Neutron diffraction techniques of large-volume samples at high pressure using compact opposed-anvil cells are developed at a reactor neutron source, China＇s Mianyang research reactor. We achieve a high-pressure condition of in situ neutron diffraction by means of a newly designed large-volume opposed-anvil cell. This pressure calibration is based on resistance measurements of bismuth and the neutron diffraction of iron. Pressure calibration experiments are performed at room temperature for a new cell using the tungsten carbide anvils with a tapered angle of 30°, Φ4.5 mm culet diameter and the metal-nonmetal composite gasket with a thickness of 2 mm. Transitions in Bi（Ⅰ–Ⅱ 2.55 GPa, Ⅱ–V 7.7 GPa） are observed at 100 and 300 kN, respectively, by resistance measurements.The pressure measurement results of neutron diffraction are consistent with resistance measurements of bismuth.As a result, pressures up to about 7.7 GPa can routinely and stably be achieved using this apparatus, with the sample volume of 9 mm^3.

Electrospinning-hot pressing technique for the fabrication of thermal and electrical storage membranes and its applications

The combination of electrospinning and hot pressing,namely the electrospinning-hot pressing technique(EHPT),is an efficient and convenient method for preparing nanofibrous composite materials with good energy storage performance.The emerging composite membrane prepared by EHPT,which exhibits the advantages of large surface area,controllable morphology,and compact structure,has attracted immense attention.In this paper,the conduction mechanism of composite membranes in thermal and electrical energy storage and the performance enhancement method based on the fabrication process of EHPT are systematically discussed.Moreover,the state-of-the-art applications of composite membranes in these two fields are introduced.In particular,in the field of thermal energy storage,EHPT-prepared membranes have longitudinal and transverse nanofibers,which generate unique thermal conductivity pathways;also,these nanofibers offer enough space for the filling of functional materials.Moreover,EHPT-prepared membranes are beneficial in thermal management systems,building energy conservation,and electrical energy storage,e.g.,improving the electrochemical properties of the separators as well as their mechanical and thermal stability.The application of electrospinning-hot pressing membranes on capacitors,lithium-ion batteries(LIBs),fuel cells,sodium-ion batteries(SIBs),and hydrogen bromine flow batteries(HBFBs)still requires examination.In the future,EHPT is expected to make the field more exciting through its own technological breakthroughs or be combined with other technologies to produce intelligent materials.

Ultrahigh strength and improved electrical conductivity in an aging strengthened copper alloy processed by combination of equal channel angular pressing and thermomechanical treatment

In this paper,equal channel angular pressing and thermomechanical treatment was employed to improve the strength and electrical conductivity of an aging strengthened Cu-Ti-Cr-Mg alloy,and the microstructure and properties of the alloy were investigated in detail.The results showed that the samples deformed by the combination of cryogenic equal channel angular pressing(ECAP)and rolling had good comprehensive properties after aging at 400℃.The tensile strength of the peak-aged and over-aged samples was 1120 MPa and 940 MPa,with their corresponding electrical conductivity of 14.7%IACS and 22.1%IACS,respectively.ECAP and cryogenic rolling introduced high density dislocations,leading to the inhibition of the softening effects and refinement of the grains.After a long time aging at 400℃,the alloy exhibited ultra-high strength with obvious increasing electrical conductivity.The high strength was attributed to the synergistic effect of work hardening,grain refinement strengthening and precipitation strengthening.The precipitation of a large amount of Ti atoms from the matrix led to the high electrical conductivity of the over-aged sample.

Chemical Composition of Pineapple Press Residues (Ananas comosus) and Effect on Growth Performance of Rabbit (Oryctolagus cuniculus)

With a view to improving rabbit production performance, a trial on the chemical composition of pineapple press residue (Ananas comosus) and the effect of its incorporation in the ration on rabbit growth performance (Oryctolagus cuniculus) was carried out at the KUATE Cunicole Farm in Bandjoun, in Western Cameroon. To do this, 36 rabbits of the local breed, aged 53 days with an average weight of 1337 ± 119 g were distributed and randomly assigned to 3 experimental rations corresponding respectively to treatments or batches T0, T1 and T2. The animals in treatment T0 received a ration containing no pineapple press residue, while those in treatments T1 and T2 received a ration containing 20% and 40% pineapple press residue, respectively. These residues were dried and ground for chemical composition analysis. The feed served as well as refusals from the previous day were weighed each morning to assess feed intake. The animals were weighed every 7 days to assess weight performance. At the end of the trial which lasted 7 weeks, the animals were fasted for 24 hours, then sacrificed to evaluate carcass characteristics and the relative weights of some digestive organs. The results of this study showed that pineapple press residues had a high crude fiber content (19.2%) and energy (2500 Kcal/kg DM). Their incorporation had no significant effect on feed intake and feed conversion ratio. The average live weight, weight gain and average daily weight gain of the animals receiving the ration with 20% inclusion of pineapple press residue were comparable to those of the control group and significantly higher than those of animals fed with 40% inclusion of pineapple residue. The highest carcass yields were obtained with rabbits fed 20% pineapple press residue in their ration. The cost of feed for the production of a kilogram live weight of rabbit tends to decrease with the ration incorporated with 20% pineapple press residue. Pineapple press residues constitute a by-product that can be recycled and their incorporation at 20% can increase rabbit growth performance and reduce production costs.

Effect of hot isostatic pressure on the microstructure and tensile properties of γ'-strengthened superalloy fabricated through induction-assisted directed energy deposition

The microstructure characteristics and strengthening mechanism of Inconel738LC(IN-738LC) alloy prepared by using induction-assisted directed energy deposition(IDED) were elucidated through the investigation of samples subjected to IDED under 1050℃ preheating with and without hot isostatic pressing(HIP,1190℃,105 MPa,and 3 h).Results show that the as-deposited sample mainly consisted of epitaxial columnar crystals and inhomogeneously distributed γ’ phases in interdendritic and dendritic core regions.After HIP,grain morphology changed negligibly,whereas the size of the γ’ phase became increasingly even.After further heat treatment(HT,1070℃,2 h + 845℃,24 h),the γ’ phase in the as-deposited and HIPed samples presented a bimodal size distribution,whereas that in the as-deposited sample showed a size that remained uneven.The comparison of tensile properties revealed that the tensile strength and uniform elongation of the HIP + HTed sample increased by 5% and 46%,respectively,due to the synergistic deformation of bimodal γ’phases,especially large cubic γ’ phases.Finally,the relationship between phase transformations and plastic deformations in the IDEDed sample was discussed on the basis of generalized stability theory in terms of the trade-off between thermodynamics and kinetics.

Improving mechanical properties and high-temperature oxidation of press hardened steel by adding Cr and Si

This work investigated the effect of Cr and Si on the mechanical properties and oxidation resistance of press hardened steel.Results indicated that the microstructure of the Cr-Si micro-alloyed press hardened steel consisted of lath martensite,M_(23)C_(6)carbides,and retained austenite.The retained austenite and carbides are responsible for the increase in elongation of the micro-alloyed steel.In addition,after oxidation at 930℃for 5 min,the thickness of the oxide scales on the Cr-Si micro-alloyed press hardened steel is less than 5μm,much thinner than 45.50μm-thick oxide scales on 22MnB5.The oxide scales of the Cr-Si micro-alloyed steel are composed of Fe_(2)O_(3),Fe_(3)O_(4),mixed spinel oxide(FeCr_(2)O_(4)and Fe_(2)SiO_(4)),and amorphous SiO_(2).Adding Cr and Si significantly reduces the thickness of the oxide scales and prevents the generation of the FeO phase.Due to the increase of spinel FeCr_(2)O_(4)and Fe_(2)SiO_(4)phase in the inner oxide scale and the amorphous SiO_(2)close to the substrate,the oxidation resistance of the Cr-Si micro-alloyed press hardened steel is improved.

Ballistic performance of titanium-based layered composites made using blended elemental powder metallurgy and hot isostatic pressing

Metal matrix composites tiles based on Ti-6Al-4V(Ti64)alloy,reinforced with 10,20,and 40(vol%)of either TiC or TiB particles were made using press-and-sinter blended elemental powder metallurgy(BEPM)and then bonded together into 3-layer laminated plates using hot isostatic pressing(HIP).The laminates were ballistically tested and demonstrated superior performance.The microstructure and properties of the laminates were analyzed to determine the effect of the BEPM and HIP processing on the ballistic properties of the layered plates.The effect of porosity in sintered composites on further diffusion bonding of the plates during HIP is analyzed to understand the bonding features at the interfaces between different adjacent layers in the laminate.Exceptional ballistic performance of fabricated structures was explained by a significant reduction in the residual porosity of the BEPM products by their additional processing using HIP,which provides an unprecedented increase in the hardness of the layered composites.It is argued that the combination of the used two technologies,BEPM and HIP is principally complimentary for the materials in question with the abilities to solve the essential problems of each used individually.

IPS e.max Press全瓷嵌体在后牙修复中的应用效果观察

目的:分析IPS e.max Press全瓷嵌体在后牙修复中的临床效果。方法:回顾性分析80例后牙修复患者临床资料,按照治疗方法不同分为对照组和观察组各40例。对照组采用氧化锆嵌体修复,观察组采用IPS e.max Press全瓷嵌体修复。比较两组修复效果、菌斑指数、咀嚼功能及患者满意度。结果:修复后半年观察组修复体完整性、边缘密合性、边缘变色、颜色匹配、继发龋评分分别为(0.43±0.08)分、(0.31±0.03)分、(0.49±0.06)分、(0.46±0.05)分和(1.05±0.07)分,低于对照组的(0.56±0.07)分、(0.47±0.05)分、(0.61±0.08)分、(0.58±0.06)分和(1.21±0.09)分,修复后3年观察组修复体完整性、边缘密合性、边缘变色、颜色匹配、继发龋评分分别为(0.51±0.05)分、(0.43±0.05)分、(0.61±0.07)分、(0.57±0.06)分和(0.91±0.04)分,低于对照组的(0.72±0.08)分、(0.65±0.07)分、(0.88±0.09)分、(0.72±0.08)分和(0.99±0.06)分,差异均有统计学意义(P<0.05)。修复后观察组菌斑指数(1.07±0.08)分,低于对照组的(1.71±0.09)分,修复后观察组咀嚼功能(95.46±3.41)%,优于对照组的(79.25±4.34)%,差异均有统计学意义(P<0.05)。观察组患者总满意率97.5%,高于对照组的80.0%,差异有统计学意义(P<0.05)。结论:IPS e.max Press全瓷嵌体修复后牙的临床效果优于氧化锆嵌体。

Effect of the capsule on deformation and densification behavior of nickel-based superalloy compact during hot isostatic pressing

The Shima yield criterion used in finite element analysis for nickel-based superalloy powder compact during hot isostatic pressing(HIP) was modified through uniaxial compression experiments. The influence of cylindrical capsule characteristics on FGH4096M superalloy powder compact deformation and densification behavior during HIP was investigated through simulations and experiments. Results revealed the simulation shrinkage prediction fitted well with the experimental shrinkage including a maximum shrinkage error of 1.5%. It was shown that the axial shrinkage was 1.7% higher than radial shrinkage for a cylindrical capsule with the size of ∮50 mm × 100 mm due to the force arm difference along the axial and radial direction of the capsule. The stress deviated from the isostatic state in the capsule led to the uneven shrinkage and non-uniform densification of the powder compact. The ratio of the maximum radial displacement to axial displacement increased from0.47 to 0.75 with the capsule thickness increasing from 2 to 4 mm. The pressure transmission is related to the capsule thickness, the capsule material performance, and physical parameters in the HIP process.

Effects of microstructure characteristics on the tensile properties and fracture toughness of TA15 alloy fabricated by hot isostatic pressing

Powder hot isostatic pressing(HIP) is an effective method to achieve near-net-shape manufacturing of high-quality complex thinwalled titanium alloy parts, and it has received extensive attention in recent years. However, there are few reports about the microstructure characteristics on the strengthening and toughening mechanisms of powder hot isostatic pressed(HIPed) titanium alloys. Therefore, TA15powder was prepared into alloy by HIP approach, which was used to explore the microstructure characteristics at different HIP temperatures and the corresponding tensile properties and fracture toughness. Results show that the fabricated alloy has a “basket-like structure” when the HIP temperature is below 950℃, consisting of lath clusters and surrounding small equiaxed grains belts. When the HIP temperature is higher than 950℃, the microstructure gradually transforms into the Widmanstatten structure, accompanied by a significant increase in grain size. The tensile strength and elongation are reduced from 948 MPa and 17.3% for the 910℃ specimen to 861 MPa and 10% for the 970℃ specimen.The corresponding tensile fracture mode changes from transcrystalline plastic fracture to mixed fracture including intercrystalline cleavage.The fracture toughness of the specimens increases from 82.64 MPa·m^(1/2)for the 910℃ specimen to 140.18 MPa·m^(1/2)for the 970℃ specimen.Specimens below 950℃ tend to form holes due to the prior particle boundaries(PPBs), which is not conducive to toughening. Specimens above 950℃ have high fracture toughness due to the crack deflection, crack branching, and shear plastic deformation of the Widmanstatten structure. This study provides a valid reference for the development of powder HIPed titanium alloy.

Effect of hot isostatic pressing processing parameters on microstructure and properties of Ti60 high temperature titanium alloy

Hot isostatic pressing parameters are critical to Ti60 high temperature titanium alloy castings which have wide application perspective in aerospace.In order to obtain optimal processing parameters,the effects of hot isostatic pressing parameters on defects,composition uniformity,microstructure and mechanical properties of Ti60 cast high temperature titanium alloy were investigated in detail.Results show that increasing temperature and pressure of hot isostatic pressing can reduce defects,especially,the internal defects are substantially eliminated when the temperature exceeds 920℃or the pressure exceeds 125 MPa.The higher temperature and pressure can improve the microstructure uniformity.Besides,the higher pressure can promote the composition uniformity.With the temperature increases from 880℃to 960℃,α-laths are coarsened.But with increasing pressure,the grain size of prior-βphase,the widths ofα-laths andα-colony are reduced.The tensile strength of Ti60 alloy is 949 MPa,yield strength is 827 MPa,and the elongation is 11%when the hot isostatic pressing parameters are 960℃/125 MPa/2 h,which exhibits the best match between the strength and plasticity.

Simple shear extrusion versus equal channel angular pressing:A comparative study on the microstructure and mechanical properties of an Mg alloy

Two severe plastic deformation(SPD)techniques of simple shear extrusion(SSE)and equal channel angular pressing(ECAP)were employed to process an extruded Mg-6Gd-3Y-1.5Ag(wt%)alloy at 553 K for 1,2,4 and 6 passes.The microstructural evolutions were studied by electron back scattered diffraction(EBSD)analysis and transmission electron microscopy(TEM).The initial grain size of 7.5μm in the extruded alloy was reduced to about 1.3μm after 6 SPD passes.Discontinuous dynamic recrystallization was suggested to be operative in both SSE and ECAP,with also a potential contribution of continuous dynamic recrystallization at the early stages of deformation.The difference in the shear strain paths of the two SPD techniques caused different progression rate of dynamic recrystallization(DRX),so that the alloys processed by ECAP exhibited higher fractions of recrystallization and high angle grain boundaries(HAGBs).It was revealed that crystallographic texture was also significantly influenced by the difference in the strain paths of the two SPD methods,where dissimilar basal plane texture components were obtained.The compression tests,performed along extrusion direction(ED),indicated that the compressive yield stress(CYS)and ultimate compressive strength(UCS)of the alloys after both SEE and ECAP augmented continuously by increasing the number of passes.ECAP-processed alloys had lower values of CYS and UCS compared to their counterparts processed by SSE.This difference in the mechanical responses was attributed to the different configurations of basal planes with respect to the loading direction(ED)of each SPD technique.

Superplastic behavior of a fine-grained Mg-Gd-Y-Ag alloy processed by equal channel angular pressing

An extruded Mg-6Gd-3Y-1.5Ag(wt%) alloy was processed by 6 passes of equal channel angular pressing(ECAP) at 553 K using route Bc to refine the microstructure. Electron back-scattered diffraction(EBSD) analysis showed a fully recrystallized microstructure for the extruded alloy with a mean grain size of 8.6 μm. The microstructure of the ECAP-processed alloy was uniformly refined through dynamic recrystallization(DRX). This microstructure contained fine grains with an average size of 1.3 μm, a high fraction of high angle grain boundaries(HAGBs), and nano-sized Mg_(5)Gd-type particles at the boundaries of the DRXed grains, detected by transmission electron microscopy(TEM). High-temperature shear punch testing(SPT) was used to evaluate the superplastic behavior of both the extruded and ECAP-processed alloys by measuring the strain rate sensitivity(SRS) index(m-value). While the highest m-value for the extruded alloy was measured to be 0.24 at 673 K, the ECAP-processed alloy exhibited much higher m-values of 0.41 and 0.52 at 598 and 623 K, respectively,delineating the occurrence of superplastic flow. Based on the calculated average activation energy of 118 kJ mol^(-1) and m-values close to 0.5, the deformation mechanism for superplastic flow at the temperatures of 598 and 623 K for the ECAP-processed alloys was recognized to be grain boundary sliding(GBS) assisted by grain boundary diffusion.

Selected Changes in the Microclimate Parameters inside the Large-Volume Buildings Caused by the Heat Emission from People

The paper shows selected aspects of the microclimate change inside the selected type of the large-volume buildings--sacral buildings and for comparison--in the residential apartment buildings, caused by the heat emitted by people. Microclimate parameters such as air temperature or air relative humidity change because of heat emission from people staying inside there. Exemplary methods and results of research conducted in the existing sacral buildings and in the residential apartment buildings are shown. It is based on author＇s research, whose novelty is the research of the human heat emission in case of a big number of people staying inside a large-volume building. It can be useful for sacral buildings and other large-volume buildings design and for a microclimate shaping. In some large-volume buildings as the sacral buildings with a big number of people staying inside at the same time heat emitted from people significantly influences on a microclimate. Human heat streams can be useful as a part of the heat balance of the room.

腔内注射雷珠单抗联合Ex-press引流植入术治疗新生血管性青光眼的疗效

目的探讨腔内注射雷珠单抗联合Ex-press引流植入术治疗新生血管性青光眼(NVG)的疗效。方法选取2019年7月至2020年7月我院眼科收治的NVG患者100例(100眼)作为研究对象,按照随机数字表法将其分为对照组和观察组,每组50例(50眼)。对照组给予单纯Ex-press引流植入术,观察组给予腔内注射雷珠单抗联合Ex-press引流植入术。比较2组患者治疗前后眼压、视力水平及治疗有效率。采用ELISA法测定并比较2组患者血浆及房水中转化生长因子β1(TGF-β1)和血清及房水中血管内皮生长因子(VEGF)、白介素-6(IL-6)及促红细胞生成素(EPO)水平。记录2组患者不良反应的发生情况。结果2组患者治疗后4周、3个月的眼压均较治疗前降低(P<0.05),且观察组眼压明显低于对照组(P<0.05);观察组患者治疗后4周、3个月的视力改善优于对照组(P<0.05)。观察组的治疗有效率明显高于对照组(P<0.05)。2组患者治疗后4周血浆中TGF-β1水平,血清中VEGF、IL-6水平和房水中VEGF、IL-6、TGF-β1、EPO水平均明显降低(P<0.05),且观察组降低更明显(P<0.05)。2组患者不良反应发生率比较差异无统计学意义(P>0.05)。结论腔内注射雷珠单抗联合Ex-press引流植入术治疗NVG可有效降低眼内压,改善患者视力,下调TGF-β1、EPO水平,进而提高患者治疗有效率。

Tension-Compression Asymmetry in Ultrafine-grained Commercially Pure Ti Processed by ECAP

A homogenous microstructure of ultrafine-grained (UFG) commercially pure (CP) Ti characterized by equiaxed grains/subgrains with an average grain size of about 150 nm and strong prismatic fiber texture were obtained after 4 passes of equal channel angular pressing (ECAP).Tension–compression asymmetry in yield and work hardening behavior of UFG CP Ti were investigated by uniaxial tension and compression tests.The experimental results reveal that UFG CP Ti exhibits a relatively obvious tensioncompression asymmetry in yielding and work hardening behavior.The basal and prismaticslip are suppressed either for tension or compression,which is the easiest to activate.The tension twin system{1012}<1011> easily activated in compression deformation due to the prismatic fiber texture based on the Schmidt factor,consequently resulting in a lower yield strength under compression than tension.ECAP can improve the tension-compression asymmetry of CP Ti due to grain refinement.The interaction among the dislocations,grain boundaries and deformation twins are the main work hardening mechanisms for compression deformation,while the interaction between the dislocations and grain boundaries for tension deformation.Deformation twins lead to the higher work hardening under compression than tension.