时效时间对Al-Zn-In-Mg-Ti牺牲阳极电化学性能的影响

通过比较时效不同时间的Al-5Zn-0.03In-1Mg-0.05Ti-0.1Si阳极合金的析出相、开路电位、电流效率、腐蚀形貌及电化学阻抗谱等,研究了时效时间对该阳极微观组织和电化学性能的影响。结果表明:该合金中的主要析出相为Mg Zn2相,随时效时间的增加析出相迅速长大且密度逐渐降低。时效30 min试样的电化学性能最好,开路电位约-1.0793 V(SCE),电流效率为94.5%,试样表面腐蚀坑深度很浅、腐蚀形貌非常均匀。随着时效时间延长,合金的开路电位逐渐负移,但电流效率却逐渐降低且腐蚀形貌逐渐恶化。析出相对铝基牺牲阳极的电化学性能影响较大,长时间时效不利于改善铝合金阳极的综合电化学性能。     

交流负半周对高纯铝在盐酸溶液中点蚀行为的影响

研究了阴极下限电位和阴极半周时间对高纯铝在２ｍｏｌ／Ｌ ＨＣｌ溶液中三角波动电位极化初期的伏安特性和表面形貌的影响,随极极下限电位的负移,阳极溶解电流快速减小,腐蚀箔表面蚀坑直么和密度明显降低;但在同一阴极下限电位时,随阴极半周时间的延长,阳极电流则缓慢降低。     

时效对2195铝锂合金腐蚀行为的影响

研究了2195铝锂合金在不同时效状态下的晶间腐蚀和剥落腐蚀行为.结果表明:2195合金在自然时效状态下具有较好的抗晶间腐蚀和剥落腐蚀能力,但随着在160℃时效时间的延长,其晶间腐蚀与剥落腐蚀倾向逐渐增加;在剥落腐蚀溶液中进行的极化曲线测试也表现出相同的趋势.透射电镜观察发现:2195合金主要析出相为T1相;随着时效时间延长,T1相逐渐粗化,在晶界处还会出现无析出带及平衡相.模拟相实验证实,由于T1相和无析出带的开路电位都明显低于铝基体的,在腐蚀性介质中作为阳极相优先溶解,从而导致2195合金产生晶间腐蚀及剥落腐蚀.过时效状态与峰时效状态相比,晶界平衡相增多,无析出带变宽,晶间腐蚀及剥落腐蚀程度将更加严重.     

Al-Cu-Mg-Ag新型耐热铝合金的抗腐蚀性能

通过晶间腐蚀、剥落腐蚀、电化学和透射电镜等方法研究热处理制度对Al-Cu-Mg-Ag耐热铝合金组织与抗腐蚀性能的影响。结果表明:随着时效时间的延长,合金晶内和晶界析出相逐渐长大,晶界析出相由连续分布转变为不连续分布,无沉淀析出带(PFZ)逐渐变宽,合金的抗晶界腐蚀性能和抗剥落腐蚀性能逐渐降低。基体腐蚀电位φmatrix、PFZ腐蚀电位φPFZ和晶界析出相腐蚀电位φθ在晶间腐蚀液和剥落腐蚀液中符合φmatrixφθφPFZ。具有最低腐蚀电位的PFZ决定了合金的抗腐蚀性能。随着时效时间的延长,晶界析出相的粗化使得PFZ变宽,Cu原子减少,电位负移,PFZ与基体的电位差变大,腐蚀通道变宽,合金的耐蚀性降低。不同时效状态的Al-Cu-Mg-Ag耐热铝合金的抗腐蚀能力由强至弱的顺序为:欠时效的,峰时效的,过时效的。     

Al—Li—Cu—Mg合金应力腐蚀性能及机理研究

利用恒应变速率方法研究了Al—Li—Cu—Mg合金的应力腐蚀开裂,包括时效条件及外加电位对应力腐蚀的影响,同时研究了试样表面相对氢浓度与外加电位及应力腐蚀时间的关系,实验结果表明,合金的应力腐蚀性能取决于时效条件,其中峰时效条件下最差,自然时效条件下最好,应力腐蚀敏感性及试样表面氢浓度与外加电位有关,阳极电位增加应力腐蚀敏感性,阴极电位低于临界电位时加速应力腐蚀,认为合金在应力腐蚀过程中阳极溶解与氢脆机制联合作用。     

2A97 Al-Li合金薄板时效析出与电位及晶间腐蚀的相关性研究

研究了2A97 Al-Li合金薄板不同时效后微观组织、电位及在晶间腐蚀(IGC)介质中的腐蚀特征。结果表明,随着时效时间延长,2A97 Al-Li合金中时效析出T1相等,导致合金电位下降,与之对应的合金腐蚀类型呈如下规律变化:孔蚀、晶间腐蚀(包括局部和全面晶间腐蚀)程度随时效时间延长呈先增加后降低的趋势。同时,相较T6态时效,T8态时效更加促进T1相的生成,而合金电位下降速度也更快。电位越低,晶间腐蚀程度越小,代之以大面积孔蚀程度越高。以上述研究为基础,建立了合金腐蚀类型与电位之间的相关性,对于不同时效处理时快速评价Al-Li合金的晶间腐蚀敏感性具有可行性。     

时效处理对Mg-15Y合金腐蚀性能的影响

研究了不同时效温度和时间对Mg-15Y合金在3.5%的NaC1溶液中的腐蚀行为的影响,并分析了合金的腐蚀机理。结果表明,225℃时效处理时的峰时效时间为12h,硬度值达到最大,随着时间的延长,硬度值开始下降,并在110℃左右时趋于平缓;随着浸泡时间延长,腐蚀深度和析氢量持续增加;在浸泡时间一定时,合金的腐蚀程度随时效时间的延长先增加后减小,析氢速率先增大后减小,电势电位与腐蚀电流先减小后增大;在同一时效温度下随着时效时间的延长,腐蚀宏观形貌上没有很大的变化,随着时效时间的延长,析氢量先减小后增加。     

时效制度对含钪超高强铝合金晶间腐蚀和剥落腐蚀的影响

通过晶间腐蚀、剥落腐蚀和电化学腐蚀试验,结合扫描电镜和透射电镜等分析手段,研究了含钪Al-Mg-Zn-Cu-Zr合金在不同时效状态下的的晶间腐蚀和剥落腐蚀行为。结果表明,合金抗晶间腐蚀和剥落腐蚀能力随着时效时间的延长而提高,在4.0mol/L NaCl+0.1mol/L HNO3+0.4mol/L KNO3(EXCO)溶液中测试的极化曲线也表现出相同的趋势。透射电镜观察表明,晶界析出相和晶界无沉淀析出带(PFZ)是影响合金腐蚀性能的主要因素。随着时效时间的延长,非平衡相η′和S′相逐渐向平衡相η和S相转变,晶界析出相粗化并呈链状分布,PFZ变宽。晶界粗大平衡相的不均匀分布和PFZ阻断了腐蚀的阳极通道,使合金的腐蚀敏感性降低。     

Cu含量对一种新型Al-Mg-Si合金晶间腐蚀的影响

采用浸泡腐蚀实验和电化学实验研究了Cu含量变化和热处理条件对一种新型舰载飞机用Al-Mg-Si合金的耐腐蚀性能的影响.结果表明,添加Cu后,实验合金的 腐蚀方式由点蚀转变为晶间腐蚀,且腐蚀程度随Cu含量的增加而严重;与欠时效和过时效状态相比,T6态对晶间腐蚀较敏感,与晶界析出相的连续分布有关.电化学实验表明,所有实验合金均较快进入钝态;随Cu含量的增加,实验合金的自腐蚀电位向正向变化,腐蚀电流密度增加;随时效时间的延长,点蚀电位、晶间腐蚀的临界点位和自腐蚀电位逐渐向负向变化.而点蚀电位和自腐蚀电位随时效时间呈抛物线变化,晶间腐蚀的临界电位则呈直线变化.        

挤压时效态MB8镁合金在盐水中的腐蚀行为

采用光学显微镜(OM)、扫描电镜(SEM)和能谱分析(EDS)等手段研究挤压时效态MB8镁合金在盐水浸泡条件下的腐蚀特征,并探讨合金的腐蚀机理。结果表明:合金以丝状腐蚀和点蚀这两种局部腐蚀为主要的腐蚀形式。合金经过一定时间的诱导期后发生丝状腐蚀,腐蚀前端的丝头处发生镁基体的阳极溶解,已发生腐蚀的丝尾处作为活性阴极发生析氢反应;第二相粒子对丝状腐蚀的扩展具有重要影响,横截面上丝状腐蚀随着弥散分布的第二相粒子向四周扩展,而纵截面上腐蚀丝随着第二相粒子的带状分布呈长条带状形貌特征;在丝状腐蚀还未扩展到的区域由于第二相粒子与基体之间的腐蚀微电偶作用导致基体发生阳极溶解,从而产生点蚀。     

Sn-Induced Modification of the Precipitation Pathways upon High-Temperature Ageing in an Al-Mg-Si AlloyEI北大核心CSCD

The 6xxx series aluminum alloys (Al-Mg-Si(-Cu) alloys) are widely used for the industrial applications in the lightweight construction, automotive and architecture because of their light weight, medium to high strength, excellent formability and good corrosion resistance. It has been reported that trace Sn addition can accelerate ageing kinetics and increase peak hardness of Al-Mg-Si alloys when ageing at high temperatures (> 210 degrees C). However, the mechanism about it has not been investigated comprehensively yet. For Mg-excess Al-Mg-Si alloys, when aged at 250 degrees C, the alloys are hardened by the beta'-precipitates. While after applying natural ageing prior to artificial ageing, the beta '-precipitates will be formed, with the percentage of which increasing with natural ageing time, and eventually become the main hardening precipitates. In this work, the effect of Sn on natural ageing and subsequent artificial ageing at 250 degrees C in a Mg-rich Al-Mg-Si alloy was investigated by Vickers microhardness measurements and TEM. The results show that adding a small amount (0.2%, mass fraction) of Sn in the Mg-rich Al-Mg-Si alloy can modify the precipitation pathways upon 250 degrees C-ageing: when the alloy is directly artificially aged, the beta '-precipitates are dominant, whereas when the alloy is subjected to " natural ageing+artificial ageing" treatment, upon prolonged natural ageing time, the percentage of beta '-precipitates would not increase but decrease and that of beta'-precipitates would not decrease but increase, but ultimately the beta '-precipitates are still dominant over the beta'-precipitates. The Sn-induced modification of the precipitation pathways can significantly en-hance the age-hardening potential of the alloy upon high-temperature artificial ageing. The addition of Sn increases the effective Si-concentration in the matrix, and consequently changes the precipitation pathways in the Sn-free alloy, which is different from the explanation proposed in literatures.     

时效温度和Cr含量对Cu-Ag-Cr合金性能的影响

研究了时效温度和Cr含量对70%冷轧变形的Cu-Ag-xCr合金的硬度、导电性能和耐蚀性能的影响。结果表明,Cu-Ag-xCr合金在450~500℃时效后,其硬度随时效温度增加而降低,随Cr含量增加而升高;时效温度和Cr含量对合金电导率的影响不大;随时效温度升高,合金耐蚀性降低;随Cr含量增加,腐蚀速率降低,耐蚀性提高。Cr含量为0.34%时,在450℃时效2h后,其综合性能较好,电导率为47.02 MS/m,硬度(HV0.1)达到128.34,耐腐蚀性较好。     

Corrosion behavior of under‐, peak‐, and over‐aged 6063 alloy: A comparative study

The mechanical property of age‐hardenable Al‐alloys is governed by the state of ageing, which determines the microstructure and consequently, their corrosion behavior which is a vital aspect for a number of applications. This article presents a comparative assessment of corrosion behavior of under‐, peak‐ and over‐aged Al‐Mg‐Si alloy. Corrosion characteristics have been determined via immersion tests in 0.1 M ortho‐phosphoric acid solution and intergranular corrosion (IGC) tests. Corroded surfaces are examined by field emission scanning electron micrographs‐energy dispersive spectroscopy and 3D optical profilometer. The obtained results reveal that the corrosion rate at a specific immersion time as well as the depth of IGC increases in the order for under‐, peak‐, and over‐aged states. Irrespective of the state of ageing, corrosion loss increases linearly but the rate of corrosion decreases rapidly with increasing immersion time. The dominant mode of corrosion in under‐aged alloy is identified as localized pitting, while peak‐aged is highly susceptible to IGC in contrast extensive pitting corrosion is observed for over‐aged alloy. The observed differences in corrosion behavior are explained considering characteristics of precipitates. Formation of β (Mg₂Si) in case of over‐aged alloy and presence of inclusions like AlFeMnSi particles are found to accelerate pitting corrosion.     

T6时效和T6I6时效对6005A铝合金微观组织和性能的影响

采用硬度测试、晶间腐蚀试验,透射电镜(TEM)和高分辨透射电子显微(HRTEM)分析研究6时效和T6I6时效工艺处理对6005A铝合金硬度和晶间腐蚀性能的影响。结果显示:6005A铝合金经T6峰时效175℃、12 h后,虽然硬度达到了120 HV,但存在严重的晶间腐蚀倾向,腐蚀深度约为100μm,同时,晶界上的析出相呈不连续分布,尺寸较小;经T6I6时效处理后,晶内生成细小的析出相,同时晶界的析出相呈不连续分布,但尺寸较大,此时合金可获得更高的峰值硬度(127 HV),而且其抗腐蚀能力得到显著提高,腐蚀深度约为30μm。     

Evaluation of corrosion and wear resistance of friction stir welded ZK60 alloy

Owing to the low corrosion and wear resistance of magnesium alloy, surface properties are the key factors affecting its application. But few studies have concentrated on the surface properties of friction stir welded Mg–Zn–Zr alloy. The aim of the present paper is to investigate the effects of friction stir welding (FSW) and subsequent ageing on the surface corrosion and wear resistance of ZK60 alloy. It is found that due to the significant grain refinement and redistribution of precipitates, the surface corrosion and wear resistance of ZK60 plates are enhanced by FSW. Morphology of inter-granular corrosion in base metal is changed into pitting corrosion after welding. Subsequent ageing can significantly reduce the corrosion resistance of the welded plates.     

预变形量对2519铝合金抗剥落腐蚀性能的影响

采用金相观察、硬度测试与透射电镜等方法,研究了时效前冷轧预变形量对2519铝合金晶界无沉淀带及析出相大小、分布和抗剥蚀性能的影响。结果表明：当预变形量由0％增至25％时,合金的硬度值增加且到达峰值时效时间缩短,晶界无沉淀带宽度减小,晶内析出相尺寸相应减小并趋于弥散分布。同时合金抗剥落腐蚀性能呈先下降后上升的趋势,其中预变形量为5％与15％的合金在晶粒扁平度增大以及不溶产物产生的楔应力共同作用下,抗剥蚀性能最差,剥蚀等级为E;级,25％的合金次之（EB^＋）,0％变形量的合金剥蚀等级为Es^-。     

时效析出相微结构改变对AA2024铝合金应力腐蚀行为的影响

通过恒载荷应力腐蚀实验、扫描电镜（SEM）和透射电镜（TEM）等测试方法,研究了时效处理中析出行为的变化对AA2024铝合金应力腐蚀行为的影响。结果表明,合金在T3态时对应力腐蚀较为敏感,进行T8时效处理后,合金的应力腐蚀敏感性显著降低。利用高角环形暗场成像扫描透射电镜技术（HAADF-STEM）对合金进行准原位腐蚀实验观察,研究了合金T3和T8时效状态下的腐蚀过程和析出行为的变化情况,直观地展示了不同时效状态合金的腐蚀形态：T3态的合金为晶间腐蚀形貌,T8态的合金为晶间腐蚀和晶粒腐蚀相结合。由于析出行为和腐蚀机制的改变,不同时效状态的AA2024铝合金的应力腐蚀敏感性不同。     

不同热处理态2024铝合金的腐蚀行为

分别在3.5%NaCl溶液、3.5%NaCl＋1.0%H2O2溶液和pH=12的3.5%NaCl溶液中进行动电位极化实验,研究2024 Al-Cu-Mg合金在不同热处理状态下的腐蚀行为。极化曲线表明,随着合金时效时间的延长,合金的腐蚀电位向负方向移动;向NaCl溶液中添加H2O2会使腐蚀电位正移;在pH=12的3.5%NaCl溶液中的极化曲线表现出明显的钝化现象。腐蚀试样表面表现为常见的腐蚀特征,但也有扩大的点蚀、晶间腐蚀现象出现。循环动电位极化曲线显示有宽的循环极化滞后环,不同的腐蚀模式表明合金的点蚀生长对合金的热处理状态敏感。通过显微组织分析,探讨了不同热处理状态下合金在不同NaCl溶液中的腐蚀机理。     

镀液配方及化学镀工艺对Ni-P合金镀层性能影响

通过Ni-P合金镀层硬度、耐蚀性与表面含磷量的关系,分析了镀液镍次比、pH值、络合剂、缓冲剂以及施镀温度、施镀时间、时效温度对Ni-P合金化学镀层含磷量的影响,探讨了提高镀层表面硬度、耐磨性、耐蚀性的方法.