微量稀土对6063铝合金阳极氧化膜厚度的影响

稀土能细化铝合金组织,提高其强度和塑性性能,对铝合金的后处理非常有益.以添加不同含量稀土的6063铝合金为研究对象,并对其进行阳极氧化试验,系统地研究了不同含量的稀土对阳极氧化膜厚度的影响以及氧化液硫酸浓度、硫酸温度、氧化时间、电流密度及不同的工艺参数对铝合金膜层厚度的影响,以获得最佳的添加稀土含量和最合适的阳极氧化工艺参数.结果表明,添加稀土的6063铝合金比没添加稀土的6063铝合金有较强的接受极化能力,稀土可以明显地提高6063铝合金氧化膜厚度,稀土含量以0.20 %最佳.该含量的稀土6063铝合金获得优质氧化膜的最佳工艺条件为:硫酸浓度170 g/L,硫酸温度18～22 ℃,氧化时间40 min,电流密度1.2 A/dm2.     

电子探针在6063铝合金均匀化处理中的应用

研究了电子探针在6063铝合金均匀化处理中的应用,6063铝合金试样经过不同的均匀化处理工艺后,通过电子探针对其第二相形态、数量以及分布状态进行观察,得到对应的二次电子图像(SEI)以及铁、硅、镁元素的面扫描照片,由于铁、硅的扩散程度较低,故主要通过观察均匀化处理前后镁元素的分布图和SEI形貌图,同时结合能谱仪(EDS)分析合金的微区化学成分及第二相粒子的化学成分,来判断其均匀化处理工艺的优劣。     

Sr对6063铝合金组织和性能的影响北大核心CSCD

通过电磁感应炉制备了含锶6063铝合金,对制备的试样采用光学显微镜(OM)、X射线衍射(XRD)、硬度测试、拉伸测试研究Sr含量对6063铝合金组织和性能的影响。结果表明:Sr元素的加入可以细化合金的铸态组织,改变组织形貌。当Sr含量为0.20%时,细化效果最好,合金其力学性能最优。随着Sr含量的增加,6063铝合金出现新相Al4Sr,随着组织中Al4Sr相增多,Mg2Si相的析出减少,减弱了对合金的强化效果,合金的力学性能呈下降趋势。     

建筑铝型材表面氧化膜的制备及其性能

目前,有关阳极氧化工艺参数对铝合金型材表面氧化膜的组织及性能影响的系统研究不多。对建筑用2024铝合金、7075铝合金和6063铝合金进行了表面阳极氧化改性处理,研究了阳极氧化时间、电流密度和冰乙酸添加量对表面氧化膜层的生长行为、表面形貌、膜厚、显微硬度和弹性模量的影响,并分析了其作用机理。结果表明,2024铝合金和7075铝合金表面氧化膜中都存在显微孔洞缺陷,而6063铝合金表面氧化膜较为致密均匀,没有显微孔洞缺陷存在;相同工艺条件下6063铝合金表面氧化膜的生长速度最快,其次为7075铝合金,2024铝合金表层氧化膜生长速度最慢;相同工艺条件下3种合金表面氧化膜显微硬度从小至大依次为:2024铝合金7075铝合金6063铝合金;3种合金氧化膜层的弹性模量从小至大依次为:2024铝合金7075铝合金6063铝合金。     

Al-Cu-Mg-Ag耐热铝合金均匀化处理

研究了均匀化温度和均匀化时间对Al-Cu-Mg-Ag耐热铝合金微观组织的影响,优化了合金的均匀化处理制度,并对其均匀化过程进行了动力学分析.结果表明,铸态合金组织中存在严重的枝晶偏析,晶界上有大量残留相,各元素在晶内和晶界分布不均匀.随着均匀化温度的升高或均匀化时间的延长,合金组织中的残留相逐渐溶解,晶界变得稀薄,元素...     

电解抛光在6063铝合金金相试样制备中的应用

对6063铝合金的电解抛光方法进行了研究,根据电解抛光的一般原理通过试验选定了电解抛光的温度、时间、电流和电压等参数,制备出了晶界清晰、抛光面无划痕、符合显微组织观察和分析要求的金相试样,获得了比机械抛光效果更好的6063铝合金金相制样方法。     

铸态镁合金组织和力学性能研究

对Mg-5．0Y-3．0Nd-0．5Zr镁合金进行熔铸和不同温度的均匀化退火。测试该合金的室温拉伸力学性能。并采用金相显微镜,扫描电镜等方法观察铸态和均匀化退火态组织。结果表明,添加稀土元素能使镁合金的铸态组织得到细化,Nd和Y分别以Mg4、Nd3和Mg24Y化合物形式存在,均匀化退火后,试验合金抗拉强度和伸长率得到提高．其中450℃的均匀化退火效果最好,合金的抗拉强度比铸态时的提高了18．6％,塑性提高了3．5％。     

磁场对船用铝合金在模拟海水中极化行为的影响

为了研究磁场对船用铝合金在海水中腐蚀及极化行为的影响,采用电化学测试技术对常用的船用铝合金5083、6061和6063在模拟海水中的电流密度进行了研究。结果表明:加入磁场后5083、6061和6063这3种铝合金在击穿氧化膜阶段和极化阶段的电流密度均发生了变化;在击穿氧化膜阶段,5083表现为磁场降低了其电流密度,6061、6063表现为磁场增大了其电流密度;在极化阶段,5083、6061、6063均表现为磁场提高了其电流密度。但综合击穿氧化膜阶段和极化阶段的电流密度,磁场的作用表现为提高了3种船用铝合金的电流密度,提高了材料的耐腐蚀性。     

均匀化热处理对5083铝合金难溶相与晶粒尺寸的影响EI北大核心

为研究5083铝合金均匀化过程中难溶相含量、种类以及晶粒尺寸的变化,采用金相显微镜(OM)、扫描电子显微镜(SEM)、能谱仪(EDS)、差示扫描量热仪(DSC)和X射线衍射仪(XRD)对材料组织进行表征。结果表明:铸态5083铝合金中的难溶相由Al(FeMnCr)相、Al(FeMnCr)Si相和Mg_(2)Si相组成。使用相图计算对铸态组织成分进行验证,结果与实验基本吻合。随着温度从460℃升高至560℃,导电率先升高后降低。这与组织中的弥散相析出和难溶相溶解有关。均匀化制度为540℃/10 h,560℃/10 h时,难溶相主要以针片状Al(FeMnCr)相为主,Mg_(2)Si相回溶充分,面积分数分别为0.730%和0.632%,未出现过烧组织的同时,晶内有明显的弥散相粒子析出。因此均匀化温度只有≥540℃才能实现5083铝合金凝固组织中部分难溶相的回溶。提高均匀化温度和延长均匀化时间均会增加晶粒尺寸,当均匀化温度小于540℃时,难溶相变化对晶粒长大影响不大,当均匀化温度大于540℃时,难溶相回溶的同时平均晶粒直径开始大于140μm。     

均匀化过程中铸态GH742合金的组织转变

铸态GH742合金中存在复杂的第二相组织和严重的枝晶偏析,Nb、Ti大量富集于枝晶间和MC碳化物、Laves相、δ相、(γ γ′)等析出相中.本文确定了γ基体的熔化温度为1160℃,并通过不同的均匀化处理确定了γ′相、(γ γ′)共晶、MC碳化物、Laves相、δ相、Ni_5Ce相及含氧硫稀土相等析出相的溶解温度.由于稀土相在1120℃发生熔化,提出一种GH742合金低温预处理加高温扩散的二次均匀化制度来扩大其均匀化温度区间,提高扩散退火温度,从而获得均一的组织.元素扩散计算结果表明,提高均匀化温度可以提高元素的扩散系数;Nb的偏析系数比Ti的小得多,达到完全均匀化需要很长的时间.     

Microstructural features, texture and strengthening mechanisms of nanostructured AA6063 alloy processed by powder metallurgy

Nanostructured AA6063 (NS-Al) powder with an average grain size of ∼100 nm was synthesized by high-energy attrition milling of gas-atomized AA6063 powder followed by hot extrusion. The microstructural features of the consolidated specimen were studied by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques and compared with those of coarse-grained AA6063 (CG-Al) produced by hot powder extrusion of gas-atomized powder (without using mechanical milling). The consolidated NS-Al alloy consisted of elongated ultrafine grains (aspect ratio of ∼2.9) and equiaxed nanostructured grains. A high fraction (∼78%) of high-angle grain boundaries with average misorientation angle of 33° was noticed. Microtexture evaluation by plotting pole-figures and orientation distribution function (ODF) analysis showed Copper and P texture components for both the consolidated Al alloys. Tensile test at room temperature and microhardness measurement revealed that a significant improvement in the strength of AA6063 alloy is obtained through refinement of the grain structure. The strengthening mechanisms are discussed based on the dislocation-based models. The role of high-angle and low-angle grain boundaries on the strengthening mechanisms is discussed.     

A DSC study on the precipitation kinetics of cryorolled Al 6063 alloy

The microstructural evolution and precipitation behavior of cryorolled Al 6063 alloy were investigated. The Al 6063 alloy plates were solutionized and cryorolled with thickness reduction of 25% and 93%. The phase identification and microstructure of the cryorolled Al alloy sample were carried out by XRD, electron backscattered diffraction (EBSD) analysis and TEM. The cryorolled Al alloy upon 93% thickness reduction exhibits ultrafine grain structure. The DSC results of cryorolled Al 6063 alloy obtained at different heating rate are used to calculate activation energies for the evolution of precipitates. The influence of different reduction rates on activation energy of precipitate formation in the cryorolled Al 6063 alloy was analyzed. It was clear from the present study that an ultrafine-grained Al 6063 alloy exhibits a higher driving force for the precipitation formation when compared to bulk Al alloy.     

Fatigue cracking behavior of 6063 aluminum alloy for fitting clamps of overhead conductor lines

The 6063 aluminum alloy is a candidate for fitting clamps to fasten and connect the Al alloy overhead conductor lines. The Al alloy fitting clamps with different extents of stress concentration may become quite dangerous under cyclic loading due to the wind-induced swing of the conductor lines. In this study, fatigue properties and cracking behavior of the 6063 aluminum alloy were investigated using three-point-bending specimens with different notch angles. The relationship between the nominal fatigue cracking resistance and the notch angle of the Al alloy specimens was obtained. Fatigue damage and notch angle-dependent cracking behaviors were evaluated. Fatigue reliability of the 6063 alloy specimens with different stress concentration factors was discussed combined with a grain size of the alloy.     

阴树脂粉末对换流站阀冷系统6063铝合金腐蚀的影响

为了研究UP6150阴树脂粉末对阀冷系统6063铝合金腐蚀的影响,在(50±1)℃下通电(10 m A直流电流)与不通电情况下进行了6063铝合金浸泡腐蚀试验,200 m L去离子水中加0,6,10 g阴树脂粉末,将6063铝合金浸泡不同天数测定试样腐蚀速率,分析了表面形貌及溶液中离子含量,并进行相关的电化学测试。结果表明:在通电与不通电的情况下,阴树脂粉末均加速6063铝合金腐蚀,阴树脂粉末浓度越大,腐蚀越严重; 50℃时阴树脂粉末分解,生成腐蚀性离子,加速了铝合金的腐蚀;腐蚀产物中含有大量的C、O、Al,还含有少量的N,表明阴树脂分解产物参与腐蚀过程,生成Al N(Al N-R),对铝合金造成腐蚀; 6063铝合金在阴树脂粉末溶液中自腐蚀电位负移,自腐蚀电流密度增大。     

Simulation of effects of particle size and volume fraction on Al alloy strength,elongation, and toughness by using strain gradient plasticity concept

By using the constitutive equation based on the mechanism-based strain gradient plasticity with finite element software, the yield strength, uniform elongation, and toughness of aluminum alloy 6063 with different grain sizes, different particle diameters and volume fractions were studied numerically. The toughness is defined as the product of yield strength and uniform elongation. The calculation results indicate that the grain refinement and particle refinement cannot substantially improve the uniform elongation but can increase the yield strength of Al alloy when the grain size is on the order of the micron and submicron scale. When the grain size less than 2 μm, Al alloys usually exhibit high strength and low uniform elongation, and when the grain size greater than 5 μm, the materials exhibit low strength and high elongation; in either case the toughness is low. However, in the grain size of several micrometers, the toughness of Al alloy is the highest.     

铝合金表面(Ti_xAl_y)N薄膜构成及耐磨、耐蚀性探讨

传统的阳极氧化技术可以提高铝合金的表面防护装饰性能.为了进一步扩大其应用范围,提高其使用寿命,通过磁控溅射技术,在6063铝合金的表面镀覆了一层(TixAly)N薄膜,利用薄膜测厚仪、显微硬度计、X射线衍射仪以及扫描电镜分别测量和分析了薄膜的厚度、硬度、相组成及表面形态.研究发现,6063铝合金表面镀覆(TixAly)N薄膜,可以明显提高6063铝合金的硬度.主要原因是(TixAly)N薄膜中几个强化相(TiN、AJN、Ti3AlN)硬度较高;与传统的阳极氧化膜相比,(TixAly)N薄膜与基体6063铝合金的结合性能更好,因而具有较高的致密性,有益于6063铝合金抗腐蚀和抗磨损性能提高.6063铝合金镀覆(TixAly)N薄膜后在装饰行业将有广泛的应用前景.     

Effect of annealing on precipitation, microstructural stability, and mechanical properties of cryorolled Al 6063 alloy

The effect of annealing on precipitation, microstructural stability, and mechanical properties of cryorolled Al 6063 alloy has been investigated in the present work employing hardness measurements, tensile test, XRD, DSC, EBSD, and TEM. The solution-treated bulk Al 6063 alloy was subjected to cryorolling to produce ultrafine grain structures and subsequently annealing treatment to investigate its thermal stability. The CR Al 6063 alloys with ultrafine-grained microstructure are thermally stable up to 250 °C as observed in the present work. Within the range of 150–225 °C, the size of small precipitate particles is <1 μm. These small precipitate particles pin the grain boundaries due to Zener drag effect, due to which the grain growth is retarded. The hardness and tensile strength of the cryorolled Al 6063 alloys have decreased upon subjecting it to annealing treatment (150–250 °C).     

Al—Mg—Si合金显微组织及形变机制

研究了 Al-Mg-Si 系合金6063在不同时效状态下的显微组织及循环形变特性,并结合其疲劳性能和断裂特征进行了讨论。结果表明,时效条件对显微组织和形变机制有明显的影响。在UA 和 PA 状态下,组织中的时效析出物为 GP 区,形变以位错切过的方式进行,形成不均匀的平面滑移带。在 OA 状态,组织中的时效析出物为β′相,位错绕过β′相,形成均匀的位错缠结。形变特性对合金的疲劳断裂形式有明显的影响。     

Fatigue behavior and dislocation substructures for 6063 aluminum alloy under nonproportional loadings

In this paper, the fatigue behavior and dislocation substructures of 6063 aluminum alloy were studied under several nonproportional path loadings, which were circle, ellipse, rectangle and square paths. After fatigue test the micro-structure especially the dislocation substructures of the failure materials was carefully observed with the transmission electron microscope (TEM) method. Under the same 93 MPa equivalent stress amplitude loading, the alloy has the shortest life and the most severe cyclic additional hardening with circle path loading among all the loading paths. This attributes to the complicated dislocation substructures and severe stress concentration of the alloy during the cycling process. While under the ellipse path loading, the alloy has a comparably long life and light cyclic additional hardening. The deformation of the alloy and the morphology of the dislocation substructures determine the fatigue behavior of 6063 alloy under the same equivalent stress amplitude loading. Under the circle path loading, the fatigue life decreases while the cyclic strain increases as the loading stress amplitude increases from 47 MPa to 163 MPa. The dislocation evolution of 6063 alloy during the cycling process under circle path loading was examined with TEM. It was found that the dislocation merges with each other and changes from single lines to crossed bands. The movability of dislocation reduces and the stress concentration degree rises during the cycling process.     

Experimental investigation on newly developed ultrafine-grained aluminium based nano-composites with improved mechanical properties

The present work describes the structural evolution associated with grain refinement and superior mechanical properties by the addition of nano-size Al₂O₃ and Y₂O₃ particulates into monolithic A16063 alloy matrix. Mechanical milling (MM) and mechanical alloying (MA) was employed to obtain nanostructured A16063 alloy matrix with uniform distribution of ceramic reinforcement particulates. The milled-compacted-sintered samples were hot extruded to further densify the nano-composites and make the distribution of particles uniform in the material. The final hot extruded samples were examined by high resolution-scanning electron microscopy (HR-SEM), field emission-scanning electron microscopy (FESEM), X-ray diffraction (XRD) analysis and were mechanically tested for hardness and mechanical strength. Detailed (transmission electron microscopy) TEM studies were carried out for hybrid reinforced nano-composites which exhibit superior properties over monolithic Al6063 alloy and singular reinforced nano-composites. Results show that the 0.2% yield strength (0.2% YS), ultimate tensile strength (UTS), work of fracture (WOF) were improved over the unreinforced monolithic A16063 alloy and failure strain was decreased in reinforced nano-composites.