Corrosion behavior of 2A97 Al-Cu-Li alloys in different thermomechanical conditions by quasi-in-situ analysis

As a promising material in the aircraft industry,2A97 Al-Cu-Li alloy exhibits high corrosion susceptibility that may limit its application.In the present work,to illustrate the influences of precipitate and grain-stored energy on localized corrosion evolution in 2A97 Al-Cu-Li alloy,cold working and artificial aging were carried out to produce 2A97 Al-Cu-Li alloys under different thermomechanical conditions.Quasi-in-situ analysis,traditional immersion test and electrochemical measurement were then conducted to examine the corrosion behavior of 2A97 alloys.It is revealed that precipitate significantly affects Cu enrichment at corrosion fronts,which determines corrosion susceptibility of alloys,whereas grain-stored energy distribution is closely associated with localized corrosion propagation.It is also indicated that quasi-in-situ analysis exhibits a consistent corrosion evolution with traditional immersion tests,which is regarded as a proper method to explore localized corrosion mechanisms by providing local microstructural information with enhanced time and spatial resolutions.

A Seismic Facies Analysis to Determine the Relative Age and History of the Al Idrissi Mud Volcano from Offshore Larache Located in the NW Moroccan Atlantic Margin

Formed on top of the Gulf of Cadiz, the Al Idrissi mud volcano is the shallowest and largest mud volcano in the El Arraiche mud volcano field of the northwestern Moroccan margin. The development and morphology of mud volcanoes from the El Arraiche mud volcanoes group have been studied at a large scale. However, the time interval related to their formation period still needs to be better understood. In this regard, we interpreted and analyzed the seismic facies from the 2D reflection data of the GEOMARGEN-1 campaign, which took place in 2011. The aim was to identify the seismic sequences and draw the Al Idrissi mud volcano system to determine the formation period of the Al Idriss mud volcano. And as a result, the Al Idrissi mud volcano system is made of both buried and superficial bicone and was identified along with the Upper Tortonian to Messinian-Upper Pliocene facies. As the initial mud volcano extrusive edifice, the buried bicone was formed in the Late-Messinian to Early-Pliocene period. However, the superficial bicone, as the final extrusive edifice, was included in the Late Pliocene. In this case, the timing interval between the buried and superficial bicone is equivalent to the Late-Messinian to Upper-Pliocene period. Therefore, the latter corresponds to the Al Idrissi mud volcano formation period.

基于MCR-ALS-PLS对发酵液中葡萄糖的定量分析

葡萄糖浓度是生物发酵过程中的重要参数,精确控制葡萄糖浓度,可以优化发酵条件,提高生产效率和产品质量。然而大多数情况下,由于发酵液中物质复杂,导致葡萄糖的拉曼特征峰难以明确。针对这种情况下的葡萄糖定量分析,首先使用多元曲线分析-交替最小二乘(MCR-ALS)算法将葡萄糖拉曼光谱与发酵液基质光谱分离,然后采用竞争自适应重加权采样(CARS)算法进行降维和偏最小二乘2(PLS)算法进行浓度建模。结果表明使用这种方法建模的预测效果得到明显提高,测试集R由0.86026提升到了0.98031,均方根误差(RMSE)由0.00183降低到了0.00061。

Mn微合金化Al-Si-Cu-Mg合金显微组织及耐蚀性能研究

Al-Si-Cu-Mg系列合金具有优异的强韧性,但其中的含Cu强化相极大地影响了该系合金的耐蚀性能。因此,本文通过对不同Mn含量的Al-7Si-2Cu-0.6Mg合金进行显微组织观察和电化学分析,探究Mn元素的添加对T6热处理状态下合金微观结构和耐蚀性的影响。结果表明,Mn添加量的提高对合金显微硬度几乎没有影响,但在合金基体中可以观察到弥散相。随着Mn含量升高,合金的耐蚀性呈现先升高后降低的趋势。添加0.360%Mn(质量分数)合金具有最佳耐蚀性,腐蚀电流密度比基础合金减少了54%。腐蚀形貌观察结果表明,Mn的添加可以显著减弱合金的点蚀趋势。

基于MCR-ALS高光谱重构的鲑鱼脂肪可视化研究

人们对鱼类的品质追求越来越高,因此对于开发水产养殖中鱼类重要参数脂肪含量的检测显得愈发的重要,传统的检测方法虽然经过许多研究人员的修改和改进,但仍然存在费时费力,需要专业的人员培训存在一些问题。光谱技术也存在仅使用整条鱼片作为预测样本,缺乏普遍性,整个鱼片的成分分布不均匀,采样时间过长等导致图像质量不高等问题,该研究通过MCR-ALS算法重建后的数据和图像的增益效果,评估了采用近红外高光谱成像技术预测并实现鲑鱼片重要参数(脂肪)可视化的可行性。首先将购买的新鲜三文鱼按照背面和腹部切块分割,每条三文鱼制作成20个样本,共100个样本,其中75个样本用于校正集,25个样本用于预测集。用高光谱成像系统采集三文鱼样本的光谱数据,再通过索氏提取器测定三文鱼脂肪的含量,并建立其理化值样本,然后通过MCR-ALS对光谱数据进行重构,发现重构后的光谱有效信息随着组分推荐评分上升,通过连续投影算法(SPA)选择特征波长,并建立最小二乘支持向量机(LS-SVM)模型评估两种预测效果(原始和重建数据)。MCR-ALS-SPA-LS-SVM的预测精度最高,R_(p)=0.9555,RMESP=1.6505,RPD=3.3899;采用MCR-ALS和未处理的模型对鱼片脂肪进行视觉图像预测,大大减少了噪音的输入,有效还原了鱼片的轮廓,并且令鱼的脂肪条纹更加的清晰,图像质量更优。进一步分析聚类图像,通过不同成分的主成分贡献和相同成分的主成分贡献比,发现类别为20种时,样品与背景簇存在干扰,然而采用少量的簇类分析发现,仅5和10个种类即可完整描绘出整个样品的轮廓,对于光谱强反应物质存在很好的聚类效果,具有简化模型的可能。无论是数据还是图像,令人满意的预测结果证实了近红外高光谱成像用于鲑鱼脂肪定量和视觉图像预测的可行性,并且算法的优化大大缩短了检测时间,为实时在线检测创造了更好的条件。

Finite element analysis of temperature and stress fields during selective laser melting process of Al−Mg−Sc−Zr alloy

A 3D finite element model was established to investigate the temperature and stress fields during the selective laser melting process of Al−Mg−Sc−Zr alloy.By considering the powder−solid transformation,temperaturedependent thermal properties,latent heat of phase transformations and molten pool convection,the effects of laser power,point distance and hatch spacing on the temperature distribution,molten pool dimensions and residual stress distribution were investigated.Then,the effects of laser power,point distance and hatch spacing on the microstructure,density and hardness of the alloy were studied by the experimental method.The results show that the molten pool size gradually increases as the laser power increases and the point distance and hatch spacing decrease.The residual stress mainly concentrates in the middle of the first scanning track and the beginning and end of each scanning track.Experimental results demonstrate the accuracy of the model.The density of the samples tends to increase and then decrease with increasing laser power and decreasing point distance and hatch spacing.The optimum process parameters are laser power of 325−375 W,point distance of 80−100μm and hatch spacing of 80μm.

Impact analysis of casting parts considering shrinkage cavity defect

Shrinkage cavity may be detrimental to mechanical performances of casting parts.As a consequence,design engineers often use overly large safety factors in many designs due to insufficient understanding of quantitative effects of shrinkage cavity defects.In this paper,process of Al alloy wheel impact test was computationally analyzed for both the wheel models with and without shrinkage cavity defects.Based on shrinkage cavity data obtained from industrial CT (Computerized Tomography),the shrinkage cavity defects were modeled with SSM (Shape Simplification Method),which reconstructs shrinkage cavity defects to hollow spheroid primitives.After the impact simulation was conducted,the results show that under impact test condition,the wheel considering shrinkage cavity defects may fracture while the sound-assumed wheel may not.

Weibull analysis of effect of T6 heat treatment on fracture strength of AM60B magnesium alloy

The effect of T6heat treatment on the fracture strength and reliability of AM60B alloy was studied.The tensile specimens were poured at three different temperatures of670,685and700?C for different holding times of5,10and15min.The fluidity test was also conducted to determine the fluidity length under different pouring temperatures and holding times.According to the results,the optimum pouring temperature and holding time were determined as685?C and10min,respectively.SEM fractography of the tensile specimens reveals that the entrained oxides and oxide-related porosities are the main factors responsible for the reduction of fracture strength under the non-optimal casting conditions.The Weibull statistical approach was used to quantify the scatter of fracture strength in as-cast and heat-treated conditions.For this purpose,T6schedule was applied to the specimens prepared under the optimal casting condition.It is found that,despite minor effect on the average fracture strength,T6heat treatment improves the reliability of castings,where the Weibull modulus is increased by75%.According to the microstructural and fractography observations,this improvement is related to the evolution of more uniform microstructure and the elimination of coarse brittleβ-particles in heat-treated samples.

Finite element analysis of stress-strain localization and distribution in Al-4.5Cu-2Mg alloy

Finite element analysis has been carried out to understand the effect of various processing routes and condition on the microscale deformation behavior of Al–4.5 Cu–2 Mg alloy. The alloy has been developed through four different routes and condition, i.e. conventional gravity casting with and without refiner, rheocasting and SIMA process. The optical microstructures of the alloy have been used to develop representative volume elements（RVEs）. Two different boundary conditions have been employed to simulate the deformation behavior of the alloy under uniaxial loading. Finally, the simulated stress-strain behavior of the alloy is compared with the experimental result. It is found that the microstructural morphology has a significant impact on stress and strain distribution and load carrying capacity. The eutectic phase always carries a higher load than the α（Al） phase. The globular α（Al） grains with thinner and uniformly distributed eutectic network provide a better stress and strain distribution. Owing to this, SIMA processed alloy has better stress and strain distribution than other processes. Finally, the simulated yield strength of the alloy is verified by experiment and they have great agreement.

Precipitated phases and thermodynamic analysis during solidification of Al-Fe-X system at slow cooling rate

The solidification curves of Al 8.5Fe, Al 8.5Fe 1.7Fe, Al 8.5Fe 1.7Si 1.3V alloys were examined by DTA under the condition of slow cooling rate, the phase constitutes were examined by OM and XRD. The results show that, under slow cooling rate, the phases in Al 8.5Fe alloy are mainly α (Al) and Al 13 Fe 4, the phases in Al 8.5Fe 1.7Si alloy are mostly α (Al), Al 13 Fe 4, α AlFeSi, β AlFeSi, and comparing to Al 8.5Fe 1.7Si alloy, no other phases form in the Al 8.5Fe 1.3V 1.7Si alloy, but the chemical compositions of the phases are changed and the thermal stability of α AlFeSi phase and β AlFeSi phase is improved, due to the partial substitution of V for Fe atoms. The phase formation was calculated by Thermo calc software at equilibrium condition, the calculated results were agreement with the experimental results.

Species distribution of polymeric aluminium ferrum——timed complexation colorimetric analysis method of Al-Fe-Ferron

The effects of the calorimetric buffer solutions were investigated while the two colorimetric reactions of AI-ferron complex and Fe-ferron complex occurred individually, and the effects of the testing wavelength and the pH of the solutions were also investigated. A timed complexatian colorimetric analysis method of Al-Fe-ferron in view of the total concentration of {AI + Fe} was then established to determine the species distribution of polymeric Al-Fe. The testing wavelength was recommended at 362 net and the testing pH value was 5. With a comparison of the ratios of n(Al)/n(Fe), the standard adsorption curves of the polymeric Al-Fe solutions were derived from the experimental results. Furthermore, the solutions' composition were carious in both the molar n(Al)/n(Fe) ratios, i.e. 0/0, 5/5, 9/1 and 0/10, and the concentrations associated with the total ( Al + Fe which ranged from 10(-5) to 10(-4) mol/L..

Al-3Y-2B中间合金对Al-20Si铸态组织和力学性能的影响

研究了Al-3Y-2B中间合金对过共晶Al-20Si二元合金铸态组织及性能的影响规律,基于冷却曲线分析(CCA)方法,测得了Al-20Si二元合金中加入Al-3Y-2B中间合金前后的冷却曲线。实验结果表明:Al-20Si合金熔体加入1.0%的Al-3Y-2B中间合金后,初生硅的生成温度降低约13℃;铸态组织的初生硅平均尺寸由110μm减小到33μm,初生硅形貌由粗大的多边形结构转变为尺寸细小的板状结构;共晶硅形貌由细长针状转变为短针状和短棒状;铸态合金的伸长率(EL)由1.62%提升到1.98%,极限抗拉强度(UTS)由120 MPa提升到162 MPa。Al-3Y-2B的添加量为0.5%时,组织中的初生硅和共晶硅被很好的细化;Al-3Y-2B的添加量提高到1.0%时,Al基体中开始出现脆性相,影响合金的机械性能。

Experimental and Thermodynamic Analysis on Phase Equilibria of Ni-rich Region in Ni-Al-Ti System

Phase equilibria including γ,γ′,η,β and H in Ni Al Ti system were investigated by diffusion couple method and calculated with thermodynamic model.The experimental phase equilibria generally agree with ones reported till now.Regular solution and sublattice models were used in order to calculate these phase equilibria.The calculated results show agreement with experimental data.

Phase analysis of Al metal in complex deoxidizer

Complex deoxidizer is an important supplementary material for steelmaking,which can not only absorb liquid steel inclusions and improve the quality of molten steel,but also enhance deoxidation,desulfurization, dephosphorization,to prevent the molten steel suction and reduce the molten steel temperature loss.Currently,the complex deoxidizer all contain a certain amount of metal aluminium.The metal aluminium can not be determined for the steel.The entire aluminium contents were regarded as the content of approximate metal aluminium,that often bring great economic losses.Because A1,0,price is cheaper than metal aluminite powder,suppliers added a certain amount of Al_2O_3 in complex deoxidizer,pretend to be the metal aluminium to reap huge profits.This paper put forward a kind of method for determining aluminum,which would reduce loss of the enterprise.Research and put forward an iron triehloride,which extracted from Al metal from complex deoxidizer.Meantime,using orthogonal design of the experiment has been optimized for working conditions.The RSD of the samples are I. 07%-1.94%,the recoveries of the experiment results are 97.0%-110.0%,which expressed the precision and accuracy of the experiment are good.The establishment of the iron triehloride as a extractor,which is rapid and accurate for determination of Al metal in complex deoxidizer.

Parametric analysis of warm forming of aluminum blanks with FEA and DOE

The effect of temperature distribution on warm forming performance was investigated for 5083-O (Al-Mg) sheet metal blanks. Combined isothermal/non-isothermal FEA with design of experiments tools were used to predict appropriate warm forming temperature conditions for deep drawing and two-dimensional stamping cases. In the investigated temperature range of 25?250 ℃, the formability of Al-5083 alloy is found to be greatly dependent on the temperature distribution of the die and punch. To achieve increased degrees of forming, different temperature levels should be assigned to the corner and body of the die and punch. And the optimal temperature distributions for warm deep drawing and warm two-dimensional stamping are not identical.

Thermodynamic Analysis of Thermal Decomposition of Al(OH)_3

Thermodynamic analysis of the main reactions in the process of thermal decomposition ofAl(OH)3 was made using Temkin-Schwarzman's method and by means of regression analysis.

Analysis of the Intrinsic Uncertainties in the Laser-Driven Iron Hugoniot Experiment Based on the Measurement of Velocities

One of the most challenging tasks in the laser-driven Hugoniot experiment is how to increase the reproducibility and precision of the experimental data to meet the stringent requirement in validating equation of state models. In such cases, the contribution of intrinsic uncertainty becomes important and cannot be ignored. A detailed analysis of the intrinsic uncertainty of the aluminum-iron impedance-match experiment based on the measurement of velocities is presented. The influence of mirror-reflection approximation on the shocked pressure of Fe and intrinsic uncertainties from the equation of state uncertainty of standard material are quantified, Furthermore, the comparison of intrinsic uncertainties of four different experimental approaches is presented. It is shown that, compared with other approaches including the most widely used approach which relies on the measurements of the shock velocities of AI and Fe, the approach which relies on the measurement of the particle velocity of Al and the shock velocity of Fe has the smallest intrinsic uncertainty, which would promote such work to significantly improve the diagnostics precision in such an approach.

A quasi-isentropic model of a cylinder driven by aluminized explosives based on characteristic line analysis

A quasi-isentropic study on the process of driving a cylinder with aluminized explosives was carried out to examine the influence of the aluminum(Al) reaction rate on cylinder expansion and the physical parameters of the detonation products. Based on the proposed quasi-isentropic hypothesis and relevant isentropic theories, the characteristic lines of aluminized explosives driving a cylinder were analyzed,and a quasi-isentropic model was established. This model includes the variation of the cylinder wall velocity and the physical parameters of the detonation products with the Al reaction degree. Using previously reported experimental results, the quasi-isentropic model was verified to be applicative and accurate. This model was used to calculate the physical parameters for cylinder experiments with aluminized cyclotrimethylenetrinitramine explosives with 15.0 % and 30.0 % Al content. The results show that this quasi-isentropic model can be used not only to calculate the cylinder expansion rule or Al reaction degree, but also to calculate the physical parameters of the detonation products in the process of cylinder expansion. For explosives with 15.0 % and 30.0 % Al, 24.3 % and 18.5 % of the Al was found to have reacted at 33.9 μs and 34.0 μs, respectively. The difference in Al content results in different reaction intensity, occurrence time, and duration of two forms of reaction(diffusion and kinetic) between the Al powder and the detonation products;the post-detonation burning reaction between the Al powder and the detonation products prolongs the positive pressure action time, resulting in a continuous rise in temperature after detonation.

基于新绿原酸的紫外吸收和电化学双信号响应的Al^(3+)分析新方法研究

目的 利用新绿原酸(NCGA)与Al^(3+)的相互作用,建立一种基于NCGA的紫外吸收和电化学双信号响应的Al^(3+)分析新方法。方法 基于NCGA与单壁碳纳米管(CNTs)之间的π-π堆积作用,构建了NCGA/CNTs/GC电极。利用差分脉冲(DPV)技术和修饰电极在+0.23 V的氧化电流的下降对Al^(3+)进行定量分析。基于NCGA对Al^(3+)在325 nm处的吸收降低同时伴随365 nm新峰生成的紫外光谱响应,并且在277和340 nm处出现等吸收点,利用365 nm和325nm处的吸光度值之比(A_(365)/A_(325))对Al^(3+)进行定量分析。结果 基于NCGA的分析方法对Al^(3+)的紫外吸收在0.1~100μmol·L^(-1)呈现出良好的线性关系,检测限为0.034μmol·L^(-1);基于NCGA的修饰电极对Al^(3+)的电流响应在0.01~0.1,0.1~10和10~100μmol·L^(-1)呈现良好的线性关系,检测限为0.45 nmol·L^(-1)。生理浓度的其他金属离子和生理活性物质对两种信号测定方法均无明显干扰。在NCGA的紫外分析方法和电化学分析方法下,大鼠血清的加标回收率分别为97.4%~101%(n=3)和98.5%~99.4%(n=3)。结论 本方法具有良好的线性、选择性和准确度,并被成功用于大鼠中Al^(3+)的准确定量。该方法有望应用于Al^(3+)相关的生理和病理事件研究。

ANALYSIS OF HOT IMPREGNATED Al-Si COATINGS

The microstructure and chemical composition of the hot impregnated Al-Si coating on 08Al steel sheet were analysed by SEM,EPMA and X-ray diffraction.The coating consists of three parts:the outer is an α-Al solid solution enriched Si and γ-(Fe,Al,Si)phases;the in- termediate FeAl_3 and Fe_2Al_5 phases mainly and the inner neighbouring the substrate mainly Fe_2Al_5 phase.