2A12铝合金电化学腐蚀行为研究

采取正交试验方法,利用极化曲线和电化学阻抗谱(EIS)等电化学方法研究了2A12铝合金在不同溶液浓度、pH值以及温度的NaCl溶液中的腐蚀行为。试验结果表明,溶液浓度、pH值以及温度对2A12铝合金在NaCl溶液中耐腐蚀行为的影响依次为：pH值、温度、溶液浓度。2A12铝合金的耐腐蚀性能随着NaCl溶液浓度的增加而变差;NaCl溶液温度越高,腐蚀电流密度Icorr越大,合金耐腐蚀性能下降;溶液中性条件下,合金耐腐蚀性能最强,碱性条件下耐腐蚀性能最差;酸性条件下腐蚀电流密度Icorr随pH值的降低而增大,合金耐腐蚀性能减弱。     

电测法研究温度对2A12铝合金应力腐蚀开裂的影响

用自制的电位监测应力腐蚀装置研究了温度对硬铝合金2A12(LY12)在3.5% NaCl水溶液中腐蚀裂纹扩展的影响.结果表明:温度越高,KISCC越小,2A12铝合金的腐蚀裂纹扩展越快;2A12铝合金在NaCl水溶液中的应力腐蚀断口形貌主要表现为沿晶断裂,并具有岩石状沿晶断裂特征.     

阳极氧化时间对2A12铝合金剥落腐蚀性能的影响

利用扫描电镜(SEM)、能谱仪(EDS)以及膜厚测量等分析测试方法研究了不同阳极氧化时间对2A12铝合金抗剥落腐蚀性能的影响。结果表明：随着阳极氧化时间延长,氧化膜厚度逐渐增加,其抗剥落腐蚀性能越好。当阳极氧化时间从30 min延长至60 min时,氧化膜厚度从2.43 μm增大到4.72 μm,膜厚标准差从0.75减少至0.52。但是当阳极氧化时间超过60 min后,氧化膜厚度增长趋势缓慢,膜厚标准差逐渐趋于一水平值。宏观、微观形貌综合分析结果表明,当阳极氧化时间为60 min时,2A12铝合金的耐腐蚀性能最好。     

2A12铝合金圆管分流模热挤压过程数值模拟

运用DEFORM-3D有限元软件,对高强度2A12铝合金圆形管材分流挤压工艺过程进行数值模拟,分析挤压过程中材料流动挤压力、应力场和温度场分布以及模具出口处金属流速的分布情况.结果表明:2A12铝合金坯料在经过工作带时,温度上升约50℃,最高温度524℃.挤压杆速度超过5 mm/s时出现管材向内卷曲及竹节管现象;坯料温度在470℃时,管材内表面至外表面应力分布最均匀,管材表面质量最好.确定2A12铝合金圆管最佳挤压工艺参数为挤压杆速度5 mm/s,坯料温度470℃,模具温度450℃.     

基于Deform-3D和正交实验法的2A12铝合金等通道转角挤压工艺优化

在Deform-3D有限元数值模拟过程中应用正交实验设计方法,对2A12铝合金等通道转角挤压工艺进行优化设计,并系统分析不同工艺参数对挤压力和等效应变的影响规律。结果表明:摩擦系数与挤压角度对挤压力的影响较大;挤压角度和挤压速度对等效应变有较大影响。     

Ni-20Cr-2.5Al在Cl-溶液中腐蚀行为研究

利用电化学方法及化学浸泡法,结合OM、XRD、TEM等表面分析技术,研究机械合金化Ni-20Cr-2.5Al及粗晶Ni-20Cr-2.5Al合金的电化学腐蚀性能.实验结果表明:机械合金化方法制备的Ni-20Cr-2.5Al合金在Cl-溶液中腐蚀性能不如粗晶Ni-20Cr-2.5Al合金.相对于粗晶合金,晶粒细化是合金机械合金化后耐蚀性能降低的主要原因.     

7A52铝合金电化学局部腐蚀行为

为进一步研究7A52铝合金的耐蚀性能和应力腐蚀敏感性,运用电化学方法研究了7A52铝合金在3.5%NaCl溶液中的局部腐蚀行为.用光学显微镜、扫描电子显微镜观察了腐蚀形貌.试验结果表明,Mg₂Si首先发生阳极溶解,一些尺寸较小的Mg₂Si被完全腐蚀,产生自身的点蚀坑.然后Mg₂Si的电位正移与周围基体形成新的腐蚀电偶,其边缘基体作为阳极被腐蚀.被腐蚀的基体形成空穴,Al3+在空穴中聚集并水解,空穴中产生酸性环境.被空穴包围的Mg₂Si脱离基体,形成更大的点蚀坑.AlMnFe在整个试验中并未发生腐蚀.     

工艺参数对LY12铝合金复合涂层的影响

以恒压模式在NaOH-Na2SiO3电解液中对LY12铝合金进行微弧氧化实验,然后用强流脉冲电子束轰击,采用扫描电镜、XRD、涂层测厚仪等检测手段,研究电参数对复合涂层的影响.结果表明：电压越高,氧化时间越长,微弧氧化膜越厚;电子柬复合处理后,涂层变得平整、致密,新相α-Al2O3峰值变高,耐摩擦磨损性能增加.     

Influence of ECAP on the fatigue behavior of age-hardenable 2xxx aluminum alloy

The fatigue behavior under load control and the mechanical properties of commercial 2011 aluminum as an age-hardenable Al al-loy was studied. To estimate the effects of the equal channel angular pressi...     

Ho对AZ91镁合金腐蚀行为的影响

采用重力铸造方法制备了3种Ho改性AZ91镁合金。通过腐蚀实验对改性合金的自腐蚀和电偶腐蚀行为进行了研究。结果表明,随着Ho含量的增加,改性合金的自腐蚀性能和电偶腐蚀性能逐步提高,当Ho的质量分数为1.10%和2.16%时,合金的耐蚀性能较佳。此外,阴极的特性对改性合金的腐蚀性能有明显影响,4种材料的阴极作用由弱到强依次为:铝硅合金,纯铝,45#钢和球墨铸铁。Ho通过抑制β相的阴极作用,增加自腐蚀电位,提高了合金的腐蚀性能。     

Influence of mechanical behavior between the grains on stress fluctuation of aluminum alloy thick plate

The research on fluctuation and inhomogeneity of internal stress of aluminum alloy thick plate is theoretical and technological base for stress control technology. By using X-ray diffraction technique and mechanical test method, aluminum alloy with typical fine sub-grains, coarse recrystallized grains, and second phase was analyzed; the interactive mechanical model between grains was built for analysis of variation of internal stress within the local micro structure by imitating the actual distribution of grains. The experimental result shows that the mechanical model can effectively explain the reason for fluctuation of microscopic stress, which also proves that the inhomogeneous distribution of metal organization is the cause for the complex distribution of microscopic stress. The model can well describe stress distribution of thick plate caused by thermal deformation. Besides, it well describes mechanism of stress fluctuation.     

Investigation of stress corrosion cracking initiation of 7A52 aluminum alloy

The stress corrosion cracking(SCC) behaviour of 7A52 aluminum alloy in air and in 3.5% NaCl solution was researched by slow strain rate test(SSRT) and SEM-EDS. The SCC susceptibility was estimated with the loss of the reduction in area. The experimental results indicate that the SCC susceptibility of 7A52 aluminum alloy in 3.5% chloride solution is the highest at strain rate of 1×10-6 s-1. The lowest one is under the condition of 1×10-5 s-1. Stress concentration and anode dissolving around Al-Fe-Mn intermetallics initiate micropores which will result in microcracks. The existence of intermetallics in the microstructure may play an important role in understanding the SCC initiation mechanisms of 7A52 aluminum alloy.     

Effect of age condition on fatigue properties of 2E12 aluminum alloy

The fatigue behaviors of 2E12 aluminum alloy in T3 and T6 conditions at room temperature in air were investigated. The microstructures and fatigue fracture surfaces of the alloy were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results show that the alloy exhibits higher fatigue crack propagation (FCP) resistance in T3 condition than in T6 condition, the fatigue life is increased by 54% and the fatigue crack growth rate (FCGR) decreases significantly. The fatigue fractures of the alloy in T3 and T6 conditions are transgranular. But in T3 condition, secondary cracks occur and fatigue striations are not clear. In T6 condition, ductile fatigue striations are observed. The effect of aging conditions on fatigue behaviors is explained in terms of the slip planarity of dislocations and the cyclic slip reversibility.     

LY12装甲铝合金焊接残余应力研究

采用钻孔-电测法对LY12铝合金垂直于焊缝方向的焊接残余应力及其分布规律、产生的原因进行了分析,探讨了残余应力的消除措施.研究表明：板厚为6mm的LY12铝合金的焊接残余应力呈双向应力状态;垂直于焊缝方向的残余应力,在焊缝上的应力较大,沿远离焊缝方向逐渐减小,纵向残余应力σx比横向残余应力σy大得多.热处理后的结头强度为236.5 MPa,比未处理的强度提高58.7%.     

Influence of Aluminum Ions Implantation on Corrosion Behavior of Zircaloy-2 Alloy in 1M H2SO4

The specimens were implanted with aluminum ions with fluence ranging from 1× 10^16 to 1× 10^17 ions/cm^2 to study the effect of aluminum ion implantation on the aqueous corrosion behavior of zircaloy-2 by metal vapor vacuum arc source （MEVVA） at an extraction voltage of 40 kV. The valence states and depth distributions of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy （XPS） and Auger electron spectroscopy （AES）, respectively. Transmission electron microscopy （TEM） was used to examine the microstructure of the aluminum-implanted samples. Glancing angle X-ray diffraction （GAXRD） was employed to examine the phase transformation due to the aluminum ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zircaloy-2 in a 1 M H2SO4 solution. It is found that a significant improvement was achieved in the aqueous corrosion resistance of zircaloy-2 implanted with aluminum ions. Finally, the mechanism of the corrosion behavior of aluminum- implanted zircaloy-2 was discussed.     

Influence of oxidant KMnO4 on film—forming process of rare earth metal conversion coating on LY12 aluminum alloy

A Cu/Al galvanic couple was established to study the influence of the oxidant KMnO4 on the film-forming process of rare earth metal(REM) conversion coating on LY12 aluminum alloy.It is found that the galvanic couple simulative experiment accords with the actual immersion.and it can be substantially used to simulate the behavior of LY12 aluminum alloy inthe film-forming process.It is showed that the formation of the coating is quickened in CeCl3 Solution containing KMnO4 compared with that not containing KMnO4.XPS results reveal that the coating formed on cathode is composed of oxide or hydroxide of Ce and Mn,So the mechanism of formatiopn of REM conversion coating changes when KMnO4 is added.