加工形态对铝合金薄壁件加工变形的影响

针对航空铝合金薄壁件加工变形的问题,采用三维有限元方法,仿真分析加工形态(材料去除率、构件框数和铣削深度)对铝合金薄壁件加工变形的影响,并通过铣削实验对仿真结果的准确性进行验证。研究结果表明:构件长度方向翘曲变形量随着宽度方向材料去除率减小而减小;随着长度方向材料去除率减小,构件宽度方向变形量减小,而长度方向的变形量基本不变;当构件材料去除率大于85%时,材料去除率一致,框数不一致,构件底面翘曲变形量基本一致;当材料去除率小于85%时,同材料去除率的多框体变形比单框体的变形大;随着铣削深度增大,框类件长度和宽度方向变形量都是先增大后减小;模型仿真计算变形量与实验结果较吻合,本研究可为控制薄壁件加工变形提供参考。

汉语母语者英语形态加工、形式加工的分离——来自ERP的证据

文章通过神经电生理学手段——ERP技术对汉语母语者的英语形态加工、形式加工情况进行研究。从实验结果可以看出,汉语母语者加工英语形态错误句子时,跟形态正确句子相比,在ERP成分上表现为反映控制、整合加工的P600成分,不过波幅较小,表明汉语母语者通过积极的外显的努力能够对形态进行较好的加工;汉语母语者加工英语形式错误句子时,跟形式正确句子相比,表现在ERP成分上为反映自动加工和整合加工的LAN-P600双相波形,表明汉语母语者能够内隐地对形式进行很好的识别和加工。根据汉语母语者形态加工和形式加工所表现出来的脑电成分,我们可以认为汉语母语者英语的形态加工、形式加工有着不同的脑加工机制,汉语母语者英语形态加工、形式加工是分离的。

形态加工问题研究进展

大脑词库的形态加工问题受到理论语言学、神经语言学和认知科学的集中关注。本文从形态加工依赖的是运算还是存储、词的加工是否从形态上进行分解以及复杂形态的加工和形态加工中的语义效应等几个方面,对近年来这一领域的相关成果进行综述,并进一步分析了大脑词库中形态加工尚待研究的问题。

第二语言词汇习得的形态加工研究

二语词汇的形态是二语词汇习得中的重要研究内容,也是二语词汇习得研究中词汇的一个重要变量。二语词汇的视觉信息加工过程非常复杂,不同的词汇形态会导致不同的加工方式,从而产生不同的学习效果,形态效应广泛存在于二语词汇习得中,对不同水平的学习者作用各不相同。二语词汇形态的相似处、派生词与屈折词的加工等方面都是二语词汇习得研究的热点。除了二语词汇本身是一个多水平变量,二语词汇学习的效果也受到语言学习本身的综合影响,因此,词频、词汇输入的增显、单词象形等其他因素在词汇研究中也是重点研究的对象,词汇的多模态输入也会影响到二语词汇形态的加工。

近十年工作记忆及其对形态句法加工影响评介

工作记忆对形态句法加工起着至关重要的作用。本文总结对工作记忆模型的完善以及工作记忆影响形态句法加工敏感度的研究、工作记忆与形态加工的研究。大部分研究表明二语水平影响二语工作记忆，二语工作记忆容量可影响学习者对形态语法一致性搭配以及句法的敏感度。本文旨在回顾近十年研究，从而推动在该领域研究并逐渐向纵深发展。

国内外智障儿童形态句法习得研究综述

国外关于智障儿童的语言习得中的形态句法习得研究起步较早,并已取得较大成就。一般较常见的智障儿童有唐氏综合症儿童,威廉姆斯综合症儿童,X染色体脆折性综合症儿童及累若纳(氏)综合症儿童等。研究表明,不同类型的智障儿童在形态句法加工上都存在不同程度的损伤。与国外相比,国内研究起步较晚,并且对智障儿童语言习得的研究主要集中在词汇,句式结构等方面,形态句法加工方面的研究可以说是一块未开垦的处女地。

Hot deformation behavior of Al-9.0Mg-0.5Mn-0.1Ti alloy based on processing maps

Hot deformation behavior of extrusion preform of the spray-formed Al-9.0Mg-0.5Mn-0.1Ti alloy was studied using hot compression tests over deformation temperature range of 300-450 ℃ and strain rate range of 0.01-10 s-1. On the basis of experiments and dynamic material model, 2D processing maps and 3D power dissipation maps were developed for identification of exact instability regions and optimization of hot processing parameters. The experimental results indicated that the efficiency factor of energy dissipate （η） lowered to the minimum value when the deformation conditions located at the strain of 0.4, temperature of 300 ° C and strain rate of 1 s-1. The softening mechanism was dynamic recovery, the grain shape was mainly flat, and the portion of high angle grain boundary （〉15°） was 34%. While increasing the deformation temperature to 400 ° C and decreasing the strain rate to 0.1 s-1, a maximum value of η was obtained. It can be found that the main softening mechanism was dynamic recrystallization, the structures were completely recrystallized, and the portion of high angle grain boundary accounted for 86.5%. According to 2D processing maps and 3D power dissipation maps, the optimum processing conditions for the extrusion preform of the spray-formed Al？9.0Mg？0.5Mn？0.1Ti alloy were in the deformation temperature range of 340-450 ° C and the strain rate range of 0.01-0.1 s-1 with the power dissipation efficiency range of 38%？43%.

Hot deformation behavior and microstructural evolution of beta C titanium alloy in β phase field

The hot deformation behavior of beta C titanium alloy in β phase field was investigated by isothermal compression testson a Gleeble？3800 thermomechanical simulator. The constitutive equation describing the hot deformation behavior was obtained anda processing map was established at the true strain of 0.7. The microstructure was characterized by optical microscopy （OM）,scanning electron microscopy （SEM） and electron back-scattered diffraction （EBSD） technique. The results show that the flow stressincreases with increasing strain rates, and decreases with increasing experimental temperatures. The calculated apparent activationenergy （167 kJ/mol） is close to that of self-diffusion in β titanium. The processing map and microstructure observation exhibit adynamic recrystallization domain in the temperature range of 900-1000 ℃ and strain rate range of 0.1-1 s^-1. An instability regionexists when the strain rate is higher than 1.7 s^-1. The microstructure of beta C titanium alloy can be optimized by proper heattreatments after the deformation in the dynamic recrystallization domain.

Hot deformation behavior of high Ti 6061 Al alloy

The hot deformation behavior of a high Ti 6061 aluminum alloy in the temperature range from 350 to 510 ℃ and strain rate range from 0.001 to 10 s^-1 was investigated using stress-strain curve analysis, processing map, transmission electron microscopy and electron backscatter diffraction analysis. The results show that the peak stress decreases with increasing deformation temperatures and decreasing strain rate. The average deformation activation energy is 185 kJ/mol in the parameter range investigated. The flow stress model was constructed. The main softening mechanism is dynamic recovery. The processing map was obtained using dynamic material model, and the suggested processing window is 400-440℃ and 0.001-0.1 s^-1.

Rate controlling mechanisms in hot deformation of 7A55 aluminum alloy

The hot deformation behavior of 7A55 aluminum alloy was investigated at the temperature ranging from 300 ℃ to 450 ℃ and strain rate ranging from 0.01 s-1 to 1 s-1 on a Gleeble-3500 simulator. Processing maps were established in order to apprehend the kinetics of hot deformation and the rate controlling mechanism was interpreted by the kinetic rate analysis obeying power-law relation. The results indicated that one significant domain representing dynamic recrystallization （DRX） existed on the processing maps and lying in 410-450 ＆#176;C and 0.05-1 s-1. The conclusions of kinetic analysis correlated well with those obtained from processing maps. The apparent activation energy values calculated in the dynamic recrystallization （DRX） domain and the stability regions except dynamic recrystallization （DRX） domain were 91.2 kJ/mol and 128.8 kJ/mol, respectively, which suggested that grain boundary self-diffusion and cross-slip were the rate controlling mechanisms.

超硬工具（上海）有限公司 超大进给TAC铣刀系列

泰珂洛TAC铣刀系列是针对大型机械的平面铣削加工、三维加工而开发的切深范围为1～3mm的超大进给铣刀，用户可以根据机械功率以及加工形态来选择最适用的铣刀。采用大进给铣刀可以降低加工成本，缩短生产周期。

Hydrothermal preparation and crystal habit of X-zeolite powder

The preparation of X-zeolite powder was investigated in hydrothermal system, the crystal growth process of X-zeolite in hydrothermal condition was characterized by means of X-ray diffraction, scanning electron microscope and infrared ray. The results show that X-zeolite powder with uniform granularity and intact crystal shape can be obtained in hydrothermal system of acid-treated stellerite KG-*5CD*2KG-*9NaOHKG-*5CD*2KG-*9NaAl（OH）4KG-*5CD*2KG-*9H2O; the crystallite size is in the range of 2CD*23μm. The best reaction time of hydrothermal preparation is 6h. The formation phases of X-zeolite crystal are as follows: dissolution of feedstocks → formation of [SiO4] 4- and [AlO4] 5- tetrahedron, many-membered ring, β cage → formation of crystal nucleus and nano-particle → aggregation growth of nano-particle → coalescence growth of crystallite. The crystal habits of X-zeolite are intimately related with crystallization orientation of β cage in crystal and with its coupling stability on every crystal face family.

Processing map and hot deformation behavior of squeeze cast 6082 aluminum alloy

The hot deformation behavior and microstructure evolution of 6082 aluminum alloy fabricated through squeeze casting(SC)under different pressures were studied.The alloy was subjected to hot compression tests and 3D hot processing maps were established.The microstructure evolution was studied by optical microscope(OM),scanning electron microscope(SEM),and electron backscattered diffraction(EBSD).It is found that more dynamic recrystallization(DRX)grains are generated during the deformation of the specimen fabricated under higher SC pressure.At high temperature the effect of SC pressure on microstructure evolution weakens due to the dissolution of second phase particles.In addition,uneven second phase particles in specimens fabricated under higher SC pressure compressed with low temperature and middle strain rate would result in flow localization instability.Finally,the optimum deformation conditions for the 6082 aluminum alloy fabricated by SC were obtained at the temperatures of 430−500℃ and the strain rates of 0.01−1 s^(−1).

Determination of dynamic recrystallization parameter domains of Ni80A superalloy by enhanced processing maps

The determination of intrinsic deformation parameters inducing grain refinement mechanism of dynamic recrystallization (DRX) contributes to the relative forming process design. For Ni80A superalloy, the processing maps were constructed by the derivation of the stress-strain data coming from a series of isothermal compression tests at temperatures of 1273^-1473 K and strain rates of 0.01-10 s^-1. According to the processing maps and microstructural validation, the deformation parameter windows with DRX mechanism were separated in an innovative deformation mechanism map. In addition, the deformation activation energy representing deformation energy barrier was introduced to further optimize such windows. Finally, the enhanced processing maps were constructed and the parameter domains corresponding to DRX mechanism and lower deformation barrier were determined as follows: at ε=0.3, domains: 1296-1350 K, 0.056-0.32 s^-1 and 1350-1375 K, 0.035-0.11 s^-1;at ε=0.5, domains: 1290-1348 K, 0.2-0.5 s^-1 and 1305-1370 K, 0.035-0.2 s^-1;at ε=0.7, domains: 1290-1355 K, 0.042-0.26 s^-1;at ε=0.9, domains: 1298-1348 K, 0.037-0.224 s^-1.

Microstructure evolution and optimum parameters analysis for hot working of new type Mg-8Sn-2Zn-0.5Cu alloy

The hot deformation behavior of as-solutionized Mg 8Sn 2Zn 0.5Cu(TZC820)alloy was investigated experimentally and numerically via isothermal compression tests at 250400℃and strain rate range of 0.013 s 1 on a Gleeble 1500D thermomechanical simulator.Results show that the deformation temperature and strain rate signi cantly affected ow stress and material constants.In addition,the strain-compensated constitutive relationship was established on the basis of true stress strain curves.The main deformation mechanism for this alloy was the dynamic recrystallization(DRX),and the DRX degree was effectively enhanced with an increase in deformation temperature and a decrease in strain rate.Moreover,the cellular automaton method was used to simulate the microstructure evolution during hot compression.In addition,the processing maps were established,and the optimum deformation parameters for the as-solutionized TZC820 alloy are at 370400℃and 0.01 s 1,and at 320360℃and 13 s 1.

Morphology transformation of primary strip α phase in hot working of two-phase titanium alloy

Microstructural development in hot working of TA15titanium alloy with primary stripαstructure was investigated withthe aim to globularizeαstrips.Results show that the mechanisms of morphology transformation are the same to the spheroidizationmechanisms of lamellar structure.Boundary splitting and termination migration are more important than coarsening due to the largesize of stripα.Theαstrips are stable in annealing due to the unfavorable geometrical orientation of intra-αboundaries,the largethickness of strip and the geometrical stability ofαparticles.Predeformation and low speed deformation accelerate globularization ofαstrips in the following ways:direct changing of particle shape,promotion of boundary splitting and termination migration byincreasing high angle grain boundaries and interfacial area,promotion of coarsening by forming dislocation structures.Largepredeformation combined with high temperature annealing is a feasible way to globularize stripα.

Effects of Cu and Mg on thixoformability and mechanical properties of aluminium alloy 2014

Thixoforming is a processing method that deforms metal in a semisolid state.The advantages of this process include the production of parts with good surface finish,fine microstructures and superior mechanical properties.However,the process mostly produces parts from aluminium cast grades,thereby not fully utilising the true potential of this method.Hence,thermodynamic modelling can be used to formulate alloy compositions that favour this processing method.Here,the effects of reducing copper content and increasing silicon and magnesium contents on the thixoformability of aluminium alloy 2014 were presented.The work consists of both the modelling and experimental validation.Results showed that by increasing Si and decreasing Cu content in the alloy,the solidification interval temperature was decreased and the temperature working window between the stipulated liquid fractions was widened,two of the characteristics favouring the process.A high solid-solution temperature employed resulted in the dissolution of unfavourable Mg2Si compound.An increase in Mg content used also resulted in the formation of the compactπ-Al8FeMg3Si6 phase and the decrease in the amount of the sharp and plate-like structure of theβ-Al5FeSi phase,improving the strength of the modified alloy.Subsequent T6 heat treatment successfully further increased the strength of the modified alloy.

Corrosion behavior of hypereutectic Al-23%Si alloy (AC9A) processed by severe plastic deformation

Ultrafine-grained(UFG) hypereutectic Al-23%Si (mass fraction) alloy was achieved through equal-channel angular pressing(EACP) procedure. And the electrochemical properties after various ECAP passes were investigated in neutral NaCl solution. Potentiostatic polarization curves show that the corrosion potential of the ECAPed sample after 4 passes decreases markedly, while the corrosion current density reaches 1.37 times that of the as-cast alloy. However, the φcorr and Jcorr values after 16 passes are improved and approach those of the as-cast alloy. Immersion tests also show that the mass-loss ratio of ECAPed alloy decreases with increasing the pressing pass, which is lowered to 28.7% with the increase of pass number from 4 to 16. Pitting susceptibility of the ECAPed alloy after initial 4 passes is boosted, due to the presence of biggish voids resulted from the breakage of brittle large primary silicon crystals during ECAP. Increasing ECAP pass makes the voids evanesce and results in the homogeneous ultrafine-grained structure, contributing to a higher pitting resistance. These results indicate that enough ECAP passes are beneficial to increasing corrosion resistance of the hypereutectic Al-23%Si alloy.

Tensile properties of as-deformed 2A50 aluminum alloy in semi-solid state

Tensile properties of as-deformed 2A50 aluminum alloy were investigated in the high temperature solid and semi-solid states. The results show that temperature has almost no effect on the maximum tensile stress between 500 ℃ and 530 ℃, and the maximum tensile stress decreases rapidly when the temperature is above 532 ℃. The ductility decreases with increasing temperature and has an obvious fall when the temperature is above solidus temperature. This alloy almost has no ductility above 537 ℃, and cannot sustain tensile stress above 550℃. A brittle temperature range in which this alloy is prone to form microcracks was derived. The relation between microstructure, fraction solid and tensile properties were also investigated by examining the metallograph and fracture surface morphology of tested specimens, which could provide reference for forecasting the microcracks in this alloy occurring in semi-solid processing.