Zn含量对Ag925CuZn合金显微组织和硬度的影响

研究了Zn含量对Ag925CuZn合金显微组织和硬度的影响.结果表明:Zn显著抑制Ag925CuZn合金铸态组织中孔洞的形成,且在中间退火过程中使其晶粒粗化,在时效过程中形成具有与基体α-Ag成分、结构相同的浮凸状组织.同时,高Zn含量降低Ag925CuZn合金的固溶态硬度和时效态硬度;对于低Zn含量Ag925CuZn合金,固溶退火后合理的时效温度为200～250℃,冷变形后合理的时效温度为150～200℃.     

微量铟和锡对银合金抗变色及耐烧损性能的影响

针对饰品用斯特林银合金易发生硫化及氧化等变色现象,研究了添加微量In、Sn后合金的耐烧损、抗变色等性能。结果表明,添加0.375%的In代替Cu,可增加银合金的抗硫化变色和抗汗液腐蚀能力,但当In含量较低时反而会对抗汗液腐蚀能力造成不利影响;Sn元素对银合金的抗变色性能影响并不明显;补口合金中添加的In与Sn对925银合金中Zn的耐烧损性能影响规律及机理较为复杂;熔化次数较少、时间较短时In效果优于Sn,但Sn对Zn的保护时间较长;In与Sn含量降至一定程度都会加速Zn的烧损,而Zn对提高银合金抗变色能力上有着重要作用。可根据银合金需要重熔次数、熔化时间、服役环境来确定银合金中添加In、Sn、Zn的含量,达到所需效果。     

添加微量硅对925银合金抗硫化变色性能的影响

微量硅在925银铸造过程中可促进合金脱氧，提高合金熔体的洁净度和流动性，但过量硅会劣化合金性能。采用光学显微镜和电子显微镜研究添加微量硅(0.09%~0.15%)对925银微观组织变化的影响。结果表明，随着硅含量升高，925银合金中一次枝晶组织粗大，二次枝晶臂间距增大，当二次枝晶臂间距大于10 μm，合金断裂趋势显著增加。硅元素在925银合金中形成黑色低熔铜基共晶相，并由1~10 μm的点状相转变为8~20 μm的断续条状相，显微硬度变化与共晶二次析出相比例呈对应关系。在925银中梯度添加微量硅使合金硫化腐蚀后色差缩小，提高合金的抗硫化腐蚀变色能力。     

微量Si和Ag对低Cu/Mg比Al-Cu-Mg合金时效行为及微观组织结构演化的影响

采用计算机模拟与透射电镜相结合研究微量Si和Ag对低Cu/Mg比Al-Cu-Mg合金时效行为和微观组织结构演变的影响.结果表明:微量Si和Ag的添加改变了该合金的时效析出过程,显著增强了合金的时效硬化效应.微量Si的存在导致了合金时效早期Mg原子团簇、Cu-Mg原子团簇弥散化,而微量Ag的添加导致形成大量Mg-Ag原子团簇.微量Si和Ag极大地改变了合金时效早期的原子团簇化过程从而导致了时效过程中微观组织结构的不同演化过程.     

Cu-Zn-Ni-Sn仿金合金在人工海水和人工汗液中的腐蚀行为EI北大核心CSCD

采用色差测试、电化学测试、静态腐蚀测试、扫描电镜分析、电化学阻抗测试和X射线光电子能谱分析等方法,研究仿金Cu-Zn-Ni-Sn合金在人工海水和人工汗液中的腐蚀行为。合金在人工海水腐蚀初期的腐蚀产物层主要为较为致密的Cu2O和具有良好耐腐蚀性能的Zn O、Zn5(CO3)2(OH)6和Zn5(OH)8Cl2·H2O等氧化产物,该氧化膜两侧界面的传质过程是腐蚀反应发生的决速步骤。在人工汗液中腐蚀初期的主要腐蚀产物主要为疏松的Cu O和不稳定的Sn O,使其腐蚀产物膜疏松、易剥落。在人工汗液的腐蚀过程中,早期形成的腐蚀产物层会开裂,而裂纹末端界面的固相扩散决定了腐蚀反应的速率。     

Mg和Cu在Al-Zn-Mg合金时效初期的Monte Carlo模拟

采用Monte Carlo方法模拟研究Al-6Zn-(2Mg)和Al-10Zn-1.9Mg-(1.7Cu)合金时效初期微观结构的演变过程,并分析Mg和Cu的基本作用。结果表明:时效初期,Al-6Zn合金中的Zn原子有较强的团聚倾向,形成了明显的Zn原子簇;而在Al-6Zn-2Mg合金中出现明显的Zn原子簇、Zn-Mg原子簇及少量的Mg原子簇。Mg的作用是通过Mg和Zn原子间强烈的相互作用形成Zn、Mg原子交替排布的短程有序结构。含铜的Al-10Zn-1.9Mg-1.7Cu合金中,不仅形成了Zn原子簇、Mg原子簇和Zn-Mg原子簇,还形成了少量Zn-Cu原子簇、Mg-Cu原子簇和Zn-Mg-Cu原子簇。Cu的存在促进Zn原子和Zn-Mg原子团簇化,但对Mg原子的团簇化影响不大。     

添加微量Ag对高Zn超高强铝合金微观组织和力学性能的影响

探讨了添加微量Ag对高Zn超高强Al-Zn-Mg-Cu合金微观组织和力学性能的影响.采用力学拉伸实验、能谱分析、扫描电镜和透射电镜等手段对不同热处理方式的合金进行了分析.结果表明:向合金中添加微量Ag会促进粗大相的形成,消耗合金元素Zn、Mg,对合金力学性能不利.在采用相同的固溶时效工艺时,加Ag合金的抗拉强度降低了近40 MPa.但另一方面,Ag可以提高合金的固溶处理温度,使残留的粗大相在更高的固溶温度下较充分固溶,降低Ag对合金力学性能的不利影响.采用高温固溶处理后,加Ag合金T6态抗拉强度与不加Ag合金相当,但塑性有所下降.在时效过程中,微量Ag会促进过渡相的形成,并提高GP区和过渡相的稳定性,但使合金到达峰值的时间延长.     

具有优良钎焊性和低蒸汽压的低银Cu—Ag系合金钎料

1．一种具有良好钎焊性和低蒸汽压的低银Cu—Ag系合金钎料，组成为Ag：5％—35％、Si：2．5％～13％、Fe，Ni及Co(一种或两种以上)：1％～10％、余量：Cu及不可避免物(重量百分比，下同)。     

Zn元素对Sn0.5Ag0.7Cu/Cu接头剪切性能和时效接头组织结构的影响

为了改善Sn0.5Ag0.7Cu/Cu接头组织结构和力学性能,通过在Sn0.5Ag0.7Cu钎料中添加Zn元素,以Sn0.5Ag0.7Cu-xZn (x=0, 0.1, 0.4, 0.7, 1)钎料合金对紫铜基板进行了熔钎焊试验,并对接头进行微观组织及力学性能分析. 结果表明,改变了接头结合界面处金属间化合物(intermetallic compound,IMC)组织结构,增强了接头剪切断裂的韧性断裂特征,提高了接头抗剪强度. 当Zn元素的加入量为0.4% (质量分数)时,接头抗剪强度达到最高的47.81 MPa. 添加Zn元素等温时效处理后,对接头中IMC层的生长有着抑制作用,并且随着时效温度的提高和时效时间的延长,脆性层Cu₅Zn₈会破碎直至消失,因此在改善接头结合界面处IMC组织性能的同时,不会改变其组成和结构.     

Cu和Ag添加对TC4合金耐人工海水腐蚀性的影响

为进一步改善TC4合金性能,尤其耐海水腐蚀性,采用自耗电极真空电弧熔炼(VAR)法在TC4合金基体中加入Cu和Ag,制备分别含1%、2%Cu(质量分数,下同)的TC4-Cu和含1%Ag的TC4-Ag合金。利用电化学方法研究了不同合金在人工海水中的腐蚀行为与特征。结果表明,添加Cu和Ag后,TC4合金在人工海水中的腐蚀电位升高,腐蚀电流减小,可以有效提高TC4合金的耐腐蚀性能。     

锡元素对925银性能影响的研究

采用含锡量0%~5%的首饰铸造用铜基补口合金制备6种925银,通过对比检测925银流动性、白度、显微硬度、拉伸强度,分析微观组织成分,对比观察抗硫化腐蚀能力。实验结果表明,铜基补口合金中锡元素含量在4%时925银合金拉伸强度最高,锡含量在1%~3%时拉伸强度呈线性增加;随着锡含量提高925银合金流动性提高,显微硬度增加,抗硫化变色性能提升,合金的白度和亮度降低,色差增大;通过微观组织观察,随着锡含量增加在相界面处形成二次析出高锡固溶体组织,影响合金拉伸强度,含锡固溶体组织白度及亮度低于Ag-Cu-Zn固溶体组织。     

Electrochemical and mechanical behaviour of Sn‐2.5Ag‐0.5Cu and Sn‐48Bi‐2Zn solders

In this paper, two tin‐based alloys (Sn‐2.5Ag‐0.5Cu and Sn‐48Bi‐2Zn) are proposed as new lead‐free solders. Alloys have been developed by melting pure elements. Samples have been evaluated in terms of microstructure, corrosion resistance and mechanical features. Corrosion tests have been performed in 3% NaCl solution by polarization curves and electrochemical impedance spectroscopy (EIS). SEM observations and EDS analysis were carried out on samples before and after corrosion tests. Static monotonic tensile tests have been performed on three specimens for each alloy. SEM and EDS analysis revealed the presence of Sn‐Ag and Sn‐Cu intermetallic compounds within the Sn‐Ag‐Cu alloy. As a result of corrosion test, the Sn‐Ag‐Cu alloy showed a better corrosion resistance with respect to Sn‐Bi‐Zn. Both alloys evidenced good mechanical properties higher than the traditional Sn‐Pb system. Sn‐Ag‐Cu seems to be a suitable soldering material.     

工业纯Sn和Sn-3Ag-0.5Cu合金在沈阳大气环境下自然暴露的初期腐蚀行为

通过沈阳大气环境下的自然暴露实验研究工业纯Sn和Sn-3Ag-0.5Cu合金的早期大气腐蚀行为。采用扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)分析了表面腐蚀产物的形貌与成分。结果表明:工业纯Sn与Sn-3Ag-0.5Cu合金在沈阳工业大气环境下自然暴露后都很快发生了表面腐蚀并失泽,早期腐蚀产物疏松、龟裂并易于剥落。XPS深度分析表明:自然条件下暴露18 d后,表面腐蚀产物层厚度约为400 nm。工业大气中的悬浮物颗粒对腐蚀的形核和扩展起重要作用,Sn-3Ag-0.5Cu合金中的第二相Ag3Sn和Cu6Sn5作为阴极存在,但对大气腐蚀的加速影响不大。     

Creep corrosion cracking of Sn–3.0Ag and Sn–0.5Cu solder alloys in NaCl solution

The surface crack nucleation of Sn–3.0Ag and Sn–0.5Cu solder alloys has been examined by performing sustained tensile-loading tests in 0.9 mass% NaCl solution at room temperature. For Sn–3.0Ag alloy, many cracks nucleate and propagate on the side surface of the specimen, similarly to Sn–3.0Ag–0.5Cu alloy reported previously. For Sn–0.5Cu alloy, such cracks are not observed, and ordinary creep deformation occurs in the solution. The effect of sustained applied stress, i.e., creep, on the dissolution of ions is smaller for Sn–0.5Cu alloy than for Sn–3.0Ag alloy. The present results suggest that there are differences in the susceptibility to cracking under applied stress in a solution, i.e., creep corrosion cracking, among lead-free solder alloys.     

Surface enoblement by dissolution of Cu,Ag and Zn from single phase gold alloys

Single phase alloys with 30 at.% Au and with different proportions of Ag, Cu and Zn as additional alloying elements have been investigated with regard to selective dissolution. Measurements of rest potentials and ESCA analyses show that Cu and Zn are preferentially dissolved in aqueous solutions of chloride and small concentrations of sulphides leaving behind a surface significantly enriched in Au with a thickness of approximately 1 nm. No significant selective dissolution of Ag was observed in the solutions investigated. Only alloys containing substantial amoungs of Ag tended to become tarnished in sulphur containing solutions. It is suggested that Ag₂S is more easily formed than sulphides of Cu and Zn because also other oxidative reactions to oxides/ hydroxides of these elements take place, which is not the case for Ag. These oxides/hydroxides of Cu and Zn dissolve into the solution creating an Au-surface enrichment also in the diluted sulphide-containing solutions.     

Cu含量对Zn20Sn无铅钎料腐蚀性能影响

采用合金化原理,在Zn20Sn钎料基体中添加不同含量铜,形成新型合金Zn20SnxCu,研究铜含量对Zn20SnxCu无铅钎料腐蚀性能影响. 结果表明,当铜添加量小于4%时,随着铜添加量的增加,Zn20SnxCu钎料合金的腐蚀电位逐渐升高,腐蚀速率逐渐降低,合金耐腐蚀性逐渐增强;当铜添加量大于4%时,随着铜添加量的增加,Zn20SnxCu钎料合金的腐蚀电位逐渐降低,腐蚀速率增加,耐腐蚀性下降. Zn20SnxCu腐蚀表面主要产物为Zn₅(OH)₈Cl₂·H₂O和ZnO. 从Zn20SnxCu腐蚀性能考虑,铜最佳添加量为4%.     

不同状态FeCr8P13B5和FeCr8P13C7合金的耐蚀性能

本文以电化学方法(动电位极化曲线测量)和全浸法考察了不同状态(无定形态、无定形合金退火态以及晶态)FeCr8P13B5和FeCr8P13C7合金在氯离子介质中的耐蚀性能,结果表明(1)无定形FeCr8 P13 B5和FeCr8P13C7合金都具有优异的耐蚀性能。它们的动电位极化曲线十分相似,当极代电压为+1.5伏(SCE)以下时。试样不出现破裂电位Eb,钝态电流维持在10微安/厘米~2以下;这两种无定形耐蚀合金在30℃的0.5N-2.5NHCl、40和60℃的10％,FeCl_3、6H_2O、60℃的3.5％NaCl以及30℃的1MH_2SO_4+0.5MNaCl中全浸168小时其腐蚀速率为10~(-3)-10~(-4)毫米/年。(2)无定形FeCr8P1385和FeCr8P13C7合金经500℃1小时真空退火(晶化)处理后,后者的耐蚀性能急剧恶化,而前者仍保持无定形状态的优异耐腐蚀性能。电化学测量与全浸试验所得的结果是一致的。     

Effects of titanium addition on structural,mechanical, tribological,and corrosion properties of Al−25Zn−3Cu and Al−25Zn−3Cu−3Si alloys

To investigate the effect of grain refinement on the material properties of recently developed Al−25Zn−3Cu based alloys, Al−25Zn−3Cu, Al−25Zn−3Cu−0.01Ti, Al−25Zn−3Cu−3Si and Al−25Zn−3Cu−3Si−0.01Ti alloys were produced by permanent mold casting method. Microstructures of the alloys were examined by SEM. Hardness and mechanical properties of the alloys were determined by Brinell method and tensile tests, respectively. Tribological characteristics of the alloys were investigated by a ball-on-disc type test machine. Corrosion properties of the alloys were examined by an electrochemical corrosion experimental setup. It was observed that microstructure of the ternary A1−25Zn−3Cu alloy consisted of α, α+η and θ (Al₂Cu) phases. It was also observed that the addition of 3 wt.% Si to A1−25Zn−3Cu alloy resulted in the formation of silicon particles in its microstructure. The addition of 0.01 wt.% Ti to the Al−25Zn−3Cu and Al−25Zn−3Cu−3Si alloys caused a decrement in grain size by approximately 20% and 39% and an increment in hardness from HRB 130 to 137 and from HRB 141 to 156, respectively. Yield strengths of these alloys increased from 278 to 297 MPa and from 320 to 336 MPa while their tensile strengths increased from 317 to 340 MPa and from 334 to 352 MPa. Wear resistance of the alloys increased, but corrosion resistance decreased with titanium addition.     

纳米晶Cu-50Ag合金在酸性溶液中腐蚀行为研究

与粉末冶金法(PM)制备的常规尺寸合金对比,研究了通过热压液相还原法(LPR)和机械合金化法(MA)合成的Cu-50Ag合金粉末制备的块体纳米晶Cu-50Ag合金在酸性溶液中的腐蚀行为。结果表明:在Na_2SO_4溶液中加入H_2SO_4后,3种合金的腐蚀速度均加快。随着H_2SO_4浓度的增加,PMCu-50Ag和LPRCu-50Ag合金的腐蚀速度均未发生明显变化,而MACu-50Ag合金的腐蚀速度则加快。在Na_2SO_4溶液中,3种合金均未出现钝化现象,随着H_2SO_4的加入,合金出现了钝化现象。3种合金的腐蚀速率按PMCu-50Ag,LPRCu-50Ag和MACu-50Ag合金的顺序增加,其中LPRCu-50Ag合金的腐蚀速度略大于PMCu-50Ag合金,但明显小于MACu-50Ag合金。